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Oracle® XML DB
Developer's Guide
11g Release 2 (11.2)
E23094-04

February 2014
This manual describes Oracle XML DB. It includes guidelines
and examples for storing, generating, accessing, searching,
validating, transforming, evolving, and indexing XML data
in Oracle Database.

Oracle XML DB Developer's Guide, 11g Release 2 (11.2)
E23094-04
Copyright © 2002, 2014, Oracle and/or its affiliates. All rights reserved.
Primary Author:

Drew Adams

Contributing Author: Nipun Agarwal, Abhay Agrawal, Omar Alonso, David Anniss, Sandeepan Banerjee,
Mark Bauer, Ravinder Booreddy, Stephen Buxton, Yuen Chan, Sivasankaran Chandrasekar, Vincent Chao,
Ravindranath Chennoju, Dan Chiba, Mark Drake, Fei Ge, Janis Greenberg, Wenyun He, Shelley Higgins,
Thuvan Hoang, Sam Idicula, Namit Jain, Neema Jalali, Deepti Kamal, Bhushan Khaladkar, Viswanathan
Krishnamurthy, Muralidhar Krishnaprasad, Geoff Lee, Wesley Lin, Annie Liu, Anand Manikutty, Jack
Melnick, Nicolas Montoya, Steve Muench, Chuck Murray, Ravi Murthy, Eric Paapanen, Syam Pannala, John
Russell, Eric Sedlar, Vipul Shah, Cathy Shea, Asha Tarachandani, Tarvinder Singh, Simon Slack, Muralidhar
Subramanian, Asha Tarachandani, Priya Vennapusa, James Warner
Contributor: Reema Al-Shaikh, Harish Akali, Vikas Arora, Deanna Bradshaw, Paul Brandenstein, Lisa
Eldridge, Craig Foch, Wei Hu, Reema Koo, Susan Kotsovolos, Sonia Kumar, Roza Leyderman, Zhen Hua
Liu, Diana Lorentz, Yasuhiro Matsuda, Valarie Moore, Bhagat Nainani, Visar Nimani, Sunitha Patel, Denis
Raphaely, Rebecca Reitmeyer, Ronen Wolf
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Contents
Preface .............................................................................................................................................................. xliii
Audience....................................................................................................................................................
Documentation Accessibility ..................................................................................................................
Related Documents ..................................................................................................................................
Conventions ...............................................................................................................................................
Code Examples .........................................................................................................................................
Syntax Descriptions.................................................................................................................................

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What's New in Oracle XML DB? ........................................................................................................ xlix
Oracle Database 11g Release 2 (11.2.0.3) Deprecated Oracle XML DB Constructs ........................ xlix
Oracle Database 11g Release 2 (11.2.0.3) Other Changes in Oracle XML DB.................................. xlix
Oracle Database 11g Release 2 (11.2.0.2) New Features in Oracle XML DB.................................... xlix
Oracle Database 11g Release 2 (11.2.0.2) Deprecated Oracle XML DB Constructs ............................ li
Oracle Database 11g Release 2 (11.2.0.1) New Features in Oracle XML DB........................................ li
Oracle Database 11g Release 2 (11.2.0.1) Deprecated Oracle XML DB Constructs ........................... lii
Oracle Database 11g Release 1 (11.1) New Features in Oracle XML DB............................................ liii

Part I
1

Oracle XML DB Basics

Introduction to Oracle XML DB
Overview of Oracle XML DB ................................................................................................................. 1-1
Oracle XML DB Architecture ................................................................................................................. 1-2
APIs for XML ...................................................................................................................................... 1-4
Catalog Views Related to XML ........................................................................................................ 1-6
Overview of Oracle XML DB Repository ....................................................................................... 1-7
XML Services ............................................................................................................................... 1-7
Views RESOURCE_VIEW and PATH_VIEW......................................................................... 1-8
Oracle XML DB Repository Architecture ................................................................................ 1-8
Files and Folders ......................................................................................................................... 1-9
Oracle XML DB Protocol Architecture ................................................................................. 1-10
Programmatic Access to Oracle XML DB (Java, PL/SQL, and C) ........................................... 1-11
Oracle XML DB Features ..................................................................................................................... 1-12
XMLType Data Type ...................................................................................................................... 1-12
XMLType Tables and Columns Can Conform to an XML Schema.................................. 1-13
XMLType API........................................................................................................................... 1-13
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XML Schema Support.....................................................................................................................
XMLType Storage Models .............................................................................................................
XML/SQL Duality ..........................................................................................................................
SQL/XML Standard Functions .....................................................................................................
Automatic Rewriting of XQuery and XPath Expressions .........................................................
How XPath Expressions Are Evaluated by Oracle XML DB.............................................
Rewriting SQL Code That Contains XQuery and XPath Expressions .............................
When Can XPath Rewrite Occur?..........................................................................................
What is the XPath-Rewrite Process? .....................................................................................
Oracle XML DB Benefits......................................................................................................................
Unifying Data and Content ...........................................................................................................
Exploiting Database Capabilities...........................................................................................
Exploiting XML Capabilities ..................................................................................................
Efficient Storage and Retrieval of Complex XML Documents .................................................
Use XMLType Views If Your Data Is Not XML .........................................................................
Search XML Data using Oracle Text.............................................................................................
Build Messaging Applications using Oracle Streams Advanced Queuing ............................
Standards Supported by Oracle XML DB ........................................................................................
Oracle XML DB Technical Support....................................................................................................
Oracle XML DB Examples Used in This Manual............................................................................
Further Oracle XML DB Case Studies and Demonstrations.........................................................

2

Getting Started with Oracle XML DB
Oracle XML DB Installation...................................................................................................................
Oracle XML DB Use Cases .....................................................................................................................
Application Design Considerations for Oracle XML DB.................................................................
Structure of Your Data.......................................................................................................................
Oracle XML DB Repository Access .................................................................................................
Application Language .......................................................................................................................
Processing............................................................................................................................................
Messaging............................................................................................................................................
Storage .................................................................................................................................................
Oracle XML DB Performance.................................................................................................................
XML Storage Requirements..............................................................................................................
XML Memory Management .............................................................................................................
Use of XOBs Reduces Memory Overhead for XML Schema-Based Documents ...............
XOB Uses a Lazily-Loaded Virtual DOM................................................................................
XML Parsing Optimizations .............................................................................................................
Node-Searching Optimizations........................................................................................................
XML Schema Optimizations.............................................................................................................
Load Balancing Through Cached XML Schema............................................................................
Reduced Bottlenecks From Code That Is Not Native ...................................................................
Reduced Java Type Conversion Bottlenecks..................................................................................

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Using Oracle XML DB
Storing XML Data as XMLType ............................................................................................................. 3-1
What is XMLType?............................................................................................................................. 3-2

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Benefits of XMLType Data Type and API ...................................................................................... 3-2
Creating XMLType Tables and Columns ............................................................................................. 3-3
Partitioning or Constraining Binary XML Data using Virtual Columns ..................................... 3-3
Loading XML Content into Oracle XML DB....................................................................................... 3-5
Loading XML Content using SQL or PL/SQL............................................................................... 3-5
Loading XML Content using Java ................................................................................................... 3-6
Loading XML Content using C ........................................................................................................ 3-7
Loading Large XML Files that Contain Small XML Documents ................................................ 3-9
Loading Large XML Files using SQL*Loader ................................................................................ 3-9
Loading XML Documents into the Repository using DBMS_XDB ......................................... 3-10
Loading Documents into the Repository using Protocols ........................................................ 3-10
Character Sets of XML Documents .................................................................................................... 3-11
XML Encoding Declaration ........................................................................................................... 3-11
Character-Set Determination When Loading XML Documents into the Database............... 3-11
Character-Set Determination When Retrieving XML Documents from the Database ......... 3-12
Overview of the W3C XML Schema Recommendation................................................................. 3-13
XML Instance Documents.............................................................................................................. 3-13
XML Schema for Schemas.............................................................................................................. 3-14
Editing XML Schemas .................................................................................................................... 3-14
XML Schema Features .................................................................................................................... 3-14
Text Representation of the Purchase Order XML Schema................................................. 3-14
Graphical Representation of the Purchase-Order XML Schema....................................... 3-17
Using XML Schema with Oracle XML DB ....................................................................................... 3-18
Why Use XML Schema with Oracle XML DB? ........................................................................... 3-18
Validating Instance Documents with XML Schema ........................................................... 3-18
Constraining Instance Documents for Business Rules or Format Compliance .............. 3-18
Defining How XMLType Contents Must be Stored in the Database ............................... 3-18
Structured Storage of XML Documents ....................................................................................... 3-18
Annotating an XML Schema to Control Naming, Mapping, and Storage ............................. 3-19
Controlling How Collections Are Stored for Object-Relational XMLType Storage.............. 3-19
Declaring the Oracle XML DB Namespace ................................................................................. 3-20
Registering an XML Schema with Oracle XML DB ................................................................... 3-24
SQL Types and Tables Created During XML Schema Registration ................................. 3-25
Working with Large XML Schemas ...................................................................................... 3-26
Working with Global Elements.............................................................................................. 3-27
Creating XML Schema-Based XMLType Columns and Tables................................................ 3-28
Default Tables .................................................................................................................................. 3-29
Identifying XML Schema Instance Documents .............................................................................. 3-30
Attributes noNamespaceSchemaLocation and schemaLocation ............................................ 3-30
Dealing with Multiple Namespaces ............................................................................................. 3-31
Enforcing XML Data Integrity using the Database ........................................................................ 3-31
Comparing Partial to Full XML Schema Validation .................................................................. 3-32
Partial Validation ..................................................................................................................... 3-32
Full Validation.......................................................................................................................... 3-33
Full XML Schema Validation Costs Processing Time and Memory Usage ............. 3-33
Enforcing Referential Integrity using SQL Constraints............................................................. 3-34
DML Operations on XML Content using Oracle XML DB ........................................................... 3-37

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XPath and Oracle XML................................................................................................................... 3-38
Querying XML Content Stored in Oracle XML DB........................................................................ 3-38
PurchaseOrder XML Document ................................................................................................... 3-38
Retrieving the Content of an XML Document using Pseudocolumn OBJECT_VALUE ...... 3-39
Accessing Fragments or Nodes of an XML Document using XMLQUERY........................... 3-40
Accessing Text Nodes and Attribute Values using XMLCAST and XMLQUERY................ 3-41
Searching an XML Document using XMLEXISTS, XMLCast, and XMLQuery ..................... 3-42
Performing SQL Operations on XMLType Fragments using XMLTABLE ............................ 3-46
Accessing XML Data in Oracle XML DB using Relational Views............................................... 3-48
Breaking Up a Single Level of XML Data.................................................................................... 3-49
Breaking Up Multiple Levels of XML Data................................................................................. 3-49
Querying XML Content As Relational Data ............................................................................... 3-51
Updating XML Content Stored in Oracle XML DB........................................................................ 3-52
Updating XML Schema-Based and Non-Schema-Based XML Documents............................ 3-57
Namespace Support in Oracle XML DB ........................................................................................... 3-57
How Oracle XML DB Processes XMLType Methods and SQL Functions ................................. 3-58
Generating XML Data from Relational Data ................................................................................... 3-59
Generating XML Data from Relational Data using SQL/XML Functions ............................. 3-59
Generating XML Data from Relational Data using DBURITYPE ............................................ 3-63
XSL Transformation and Oracle XML DB ........................................................................................ 3-64
Using Oracle XML DB Repository ..................................................................................................... 3-68
Installing and Uninstalling Oracle XML DB Repository........................................................... 3-68
Oracle XML DB Provides Name-Level Locking......................................................................... 3-69
Use Protocols or SQL to Access and Process Repository Content ........................................... 3-69
Storing and Retrieving Database Content using Standard Protocols...................................... 3-70
Uploading Content to Oracle XML DB using FTP ..................................................................... 3-70
Accessing Oracle XML DB Repository Programmatically........................................................ 3-72
Accessing and Updating XML Content in the Repository........................................................ 3-73
Accessing XML Documents using SQL ................................................................................ 3-73
Repository Content is Exposed Through RESOURCE_VIEW and PATH_VIEW.......... 3-73
Use EXISTS_PATH and UNDER_PATH for Path-Based Predicates in a WHERE Clause ......
3-73
You Can Also Store Non-XML Documents in the Repository .......................................... 3-74
PL/SQL Packages to Create, Delete, Rename, Move,... Folders and Documents .......... 3-74
Accessing the Content of Documents using SQL ....................................................................... 3-74
Accessing the Content of XML Schema-Based Documents ...................................................... 3-76
Accessing Resource Content using Element XMLRef in Joins .......................................... 3-76
Updating the Content of Documents Stored in the Repository ............................................... 3-77
Updating Repository Content using Protocols.................................................................... 3-77
Updating Repository Content using SQL ............................................................................ 3-78
Updating XML Schema-Based Documents in the Repository........................................... 3-80
Controlling Access to Repository Data ........................................................................................ 3-80
Oracle XML DB Transactional Semantics ................................................................................... 3-81
Querying Metadata and the Folder Hierarchy ........................................................................... 3-81
RESOURCE_VIEW and PATH_VIEW.................................................................................. 3-81
Querying Resources in RESOURCE_VIEW and PATH_VIEW ........................................ 3-82
Oracle XML DB Hierarchical Repository Index ........................................................................ 3-86
How Documents are Stored in the Repository ........................................................................... 3-87
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Viewing Relational Data as XML From a Browser ......................................................................... 3-87
Accessing a Table or View from a Browser using DBUri SERVLET ....................................... 3-87
XSL Transformation using DBUri Servlet ........................................................................................ 3-88

Part II
4

Storing and Retrieving XML Data in Oracle XML DB

XMLType Operations
Selecting and Querying XML Data....................................................................................................... 4-1
Searching XML Documents using XPath Expressions ................................................................. 4-1
Querying XMLType Data using SQL/XML Functions XMLExists and XMLCast .................. 4-2
XMLEXISTS SQL/XML Function............................................................................................. 4-3
XMLCAST SQL/XML Function ............................................................................................... 4-4
Examples of Querying XML Data using SQL/XML Functions .................................................. 4-6
Updating XML Data.............................................................................................................................. 4-10
Updating an Entire XML Document ............................................................................................ 4-11
SQL Functions that Update XML Data ........................................................................................ 4-12
Inserting XML Elements using SQL Functions ................................................................... 4-13
UPDATEXML SQL Function......................................................................................................... 4-14
UPDATEXML and NULL Values.......................................................................................... 4-18
Updating the Same XML Node More Than Once............................................................... 4-20
Preserving DOM Fidelity When using UPDATEXML....................................................... 4-20
When DOM Fidelity is Preserved .................................................................................. 4-20
When DOM Fidelity is Not Preserved........................................................................... 4-20
Determining Whether DOM Fidelity is Preserved ...................................................... 4-20
Optimization of Oracle SQL Functions that Modify XML Data .............................................. 4-20
Creating XML Views using Oracle SQL Functions that Modify XML Data........................... 4-22
INSERTCHILDXML SQL Function .............................................................................................. 4-23
INSERTCHILDXMLBEFORE SQL Function............................................................................... 4-25
INSERTCHILDXMLAFTER SQL Function ................................................................................. 4-26
INSERTXMLBEFORE SQL Function............................................................................................ 4-27
INSERTXMLAFTER SQL Function .............................................................................................. 4-29
APPENDCHILDXML SQL Function............................................................................................ 4-30
DELETEXML SQL Function .......................................................................................................... 4-31

5

Using XQuery with Oracle XML DB
Overview of XQuery in Oracle XML DB ............................................................................................. 5-1
Overview of the XQuery Language ...................................................................................................... 5-2
Functional Language Based on Sequences ..................................................................................... 5-2
XQuery Expressions........................................................................................................................... 5-3
FLWOR Expressions .......................................................................................................................... 5-4
SQL/XML Functions XMLQUERY and XMLTABLE ......................................................................... 5-5
XMLQUERY SQL/XML Function in Oracle XML DB ................................................................. 5-6
XMLTABLE SQL/XML Function in Oracle XML DB................................................................... 5-7
When To Use XQuery .............................................................................................................................. 5-9
Predefined Namespaces and Prefixes .................................................................................................. 5-9
URI Scheme oradb: Querying Table or View Data with XQuery ................................................ 5-10

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Oracle XQuery Extension Functions .................................................................................................
ora:contains XQuery Function ......................................................................................................
ora:matches XQuery Function.......................................................................................................
ora:replace XQuery Function ........................................................................................................
ora:sqrt XQuery Function ..............................................................................................................
ora:tokenize XQuery Function ......................................................................................................
Oracle XQuery Extension-Expression Pragmas...............................................................................
XMLQUERY and XMLTABLE Examples ..........................................................................................
XQuery Is About Sequences ..........................................................................................................
Querying XML Data in Oracle XML DB Repository using XQuery........................................
Querying Table or View Data using XQuery..............................................................................
Using XQuery with XMLType Data.............................................................................................
Using Namespaces with XQuery..................................................................................................
Performance Tuning for XQuery ........................................................................................................
Rule-Based and Cost-Based XQuery Optimization ...................................................................
XQuery Optimization over Relational Data................................................................................
XQuery Optimization over XML Schema-Based XMLType Data ...........................................
Diagnosing XQuery Optimization: XMLOptimizationCheck ..................................................
Improving Performance for fn:doc and fn:collection on Repository Data .............................
Using equals_path and under_path Instead of fn:doc and fn:collection .........................
Using Oracle XQuery Pragma ora:defaultTable..................................................................
XQuery Static Type-Checking in Oracle XML DB..........................................................................
SQL*Plus XQUERY Command...........................................................................................................
Using XQuery with PL/SQL, JDBC, and ODP.NET........................................................................
Oracle XML DB Support for XQuery ................................................................................................
Support for XQuery and SQL........................................................................................................
Implementation Choices Specified in the XQuery Standard.............................................
XQuery Features Not Supported by Oracle XML DB ........................................................
XQuery Optional Features......................................................................................................
Support for XQuery Functions and Operators ...........................................................................
XQuery Functions fn:doc, fn:collection, and fn:doc-available ..........................................

6

Indexing XMLType Data
Oracle XML DB Tasks Involving Indexes ...........................................................................................
Overview of Indexing XMLType Data .................................................................................................
XMLIndex Addresses the Fine-Grained Structure of XML Data ................................................
Oracle Text Indexes............................................................................................................................
Optimization Chooses the Right Indexes to Use ...........................................................................
Deprecated Indexes for XML Data ..................................................................................................
Function-Based Indexes .............................................................................................................
CTXXPath Indexes ......................................................................................................................
Indexing XMLType Data Stored Object-Relationally .......................................................................
Indexing Non-Repeating text() Nodes or Attribute Values.........................................................
Indexing Repeating (Collection) Elements .....................................................................................
XMLIndex ..................................................................................................................................................
Advantages of XMLIndex.................................................................................................................
Structured and Unstructured XMLIndex Components................................................................

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XMLIndex Structured Component...............................................................................................
Ignore the Index Content Tables; They Are Transparent ..................................................
Data Type Considerations for XMLIndex Structured Component ..................................
XMLIndex Unstructured Component..........................................................................................
Ignore the Path Table – It Is Transparent .............................................................................
Column VALUE of an XMLIndex Path Table .....................................................................
Secondary Indexes on Column VALUE ...............................................................................
XPath Expressions that Are Not Indexed by an XMLIndex Unstructured Component
Creating, Dropping, Altering, and Examining an XMLIndex Index.......................................
Using XMLIndex with an Unstructured Component................................................................
Creating Additional Secondary Indexes on an XMLIndex Path Table ............................
Using XMLIndex with a Structured Component .......................................................................
How to Tell Whether XMLIndex is Used ....................................................................................
Turning Off Use of XMLIndex ......................................................................................................
XMLIndex Path Subsetting: Specifying the Paths You Want to Index....................................
Examples of XMLIndex Path Subsetting ..............................................................................
XMLIndex Path-Subsetting Rules..........................................................................................
Guidelines for Using XMLIndex with an Unstructured Component .....................................
Guidelines for Using XMLIndex with a Structured Component.............................................
XMLIndex Partitioning and Parallelism ......................................................................................
Asynchronous (Deferred) Maintenance of XMLIndex Indexes ...............................................
Collecting Statistics on XMLIndex Objects for the Cost-Based Optimizer .............................
Data Dictionary Static Public Views Related to XMLIndex......................................................
PARAMETERS Clause for CREATE INDEX and ALTER INDEX...........................................
Using a Registered PARAMETERS Clause for XMLIndex................................................
PARAMETERS Clause Syntax for CREATE INDEX and ALTER INDEX.......................
Usage of XMLIndex_parameters_clause ..............................................................................
Usage of XMLIndex_parameters ...........................................................................................
Usage of PATHS Clause..........................................................................................................
Usage of create_index_paths_clause and alter_index_paths_clause................................
Usage of pikey_clause, path_id_clause, and order_key_clause........................................
Usage of value_clause .............................................................................................................
Usage of async_clause .............................................................................................................
Usage of groups_clause and alter_index_group_clause ....................................................
Usage of XMLIndex_xmltable_clause...................................................................................
Usage of column_clause..........................................................................................................
Oracle Text Indexes on XML Data......................................................................................................
Creating and Using Oracle Text Indexes .....................................................................................
Oracle Text Indexes Are Used Independently of Other Indexes .............................................

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XML Schema Storage and Query: Basic
Overview of XML Schema and Oracle XML DB................................................................................
Using Oracle XML DB with XML Schema ..........................................................................................
Why XML Schema?............................................................................................................................
DTD Support in Oracle XML DB .....................................................................................................
Inline DTD Definitions ...............................................................................................................
External DTD Definitions ..........................................................................................................

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Managing XML Schemas with DBMS_XMLSCHEMA .................................................................... 7-6
Registering an XML Schema with Oracle XML DB ...................................................................... 7-7
Delete and Reload Documents Before Registering Their XML Schema .................................... 7-8
Storage and Access Infrastructure ................................................................................................... 7-8
Atomic Nature of XML Schema Registration ................................................................................ 7-8
Managing and Storing XML Schemas............................................................................................. 7-9
Debugging XML Schema Registration for XML Data Stored Object-Relationally ................... 7-9
SQL Object Types Created During XML Schema Registration, for Structured Storage.......... 7-9
Default Tables Created During XML Schema Registration ..................................................... 7-10
Do Not Use Internal Constructs Generated during XML Schema Registration .................... 7-10
Generated Names are Case Sensitive ........................................................................................... 7-11
Database Objects That Depend on Registered XML Schemas.................................................. 7-11
Listing All Registered XML Schemas........................................................................................... 7-11
Deleting an XML Schema............................................................................................................... 7-12
DBMS_XMLSCHEMA.DELETESCHEMA Options ........................................................... 7-13
XMLType Methods Related to XML Schema ................................................................................... 7-14
Local and Global XML Schemas ........................................................................................................ 7-14
Local XML Schema.......................................................................................................................... 7-14
Global XML Schema ....................................................................................................................... 7-15
DOM Fidelity ......................................................................................................................................... 7-16
What is DOM Fidelity?................................................................................................................... 7-16
SYS_XDBPD$ and DOM Fidelity for Structured Storage ......................................................... 7-16
XML Translations .................................................................................................................................. 7-17
Changing an XML Schema and XML Instance Documents for Translation .......................... 7-17
Indicating Translatable Elements in an XML Schema ........................................................ 7-17
Indicating Translation Language Attributes in an XML Instance Document................. 7-18
Making XML Documents Translatable ........................................................................................ 7-18
Operations on Translated Documents ......................................................................................... 7-24
Creating XMLType Tables and Columns Based on XML Schemas ............................................. 7-27
Specifying XMLType Storage Options for XML Schema-Based Data..................................... 7-29
Binary XML Storage of XML Schema-Based Data .............................................................. 7-30
Unstructured Storage of XML Schema-Based Data ............................................................ 7-32
Structured Storage of XML Schema-Based Data ................................................................. 7-32
Specifying Relational Constraints on XMLType Tables and Columns ................................... 7-34
Oracle XML Schema Annotations...................................................................................................... 7-34
Common Uses of XML Schema Annotations.............................................................................. 7-34
XML Schema Annotation Example .............................................................................................. 7-35
Available Oracle XML DB XML Schema Annotations .............................................................. 7-39
XML Schema Annotation Guidelines for Structured Storage .................................................. 7-41
Avoid Creation of Unnecessary Tables for Unused Top-Level Elements ....................... 7-42
Provide Your Own Names for Default Tables..................................................................... 7-42
Turn Off DOM Fidelity If Not Needed................................................................................. 7-42
Use Unordered Collection Elements When Order Doesn't Matter .................................. 7-42
Annotate Time-Related Elements with a Timestamp Data Type ..................................... 7-42
Add Table and Column Properties ....................................................................................... 7-42
Store Large Collections Out of Line ...................................................................................... 7-43
Querying a Registered XML Schema to Obtain Annotations ...................................................... 7-43

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Mapping XML Schema Data Types to Oracle XML DB Storage..................................................
Mapping XML Schema Data Types to SQL Data Types ................................................................
Example of Mapping XML Schema Data Types to SQL............................................................
Mapping XML Schema Attribute Data Types to SQL ...............................................................
Overriding the SQLType Value in an XML Schema When Declaring Attributes..........
Mapping XML Schema Element Data Types to SQL .................................................................
Overriding the SQLType Value in an XML Schema when Declaring Elements ............
Mapping simpleType to SQL ........................................................................................................
NCHAR, NVARCHAR, and NCLOB SQLType Values are Not Supported ..................
simpleType: Mapping XML Strings to SQL VARCHAR2 Versus CLOB ........................
Working with Time Zones......................................................................................................
Using Trailing Z to Indicate UTC Time Zone...............................................................
Mapping complexType to SQL .....................................................................................................
Specifying Attributes in a complexType XML Schema Declaration ................................

8

XPath Rewrite for Structured Storage
Overview of XPath Rewrite for Structured Storage ..........................................................................
Sample of XPath Expressions that Are Rewritten..............................................................................
Analyzing and Optimizing XPath Queries using Execution Plans ................................................
Guideline: Look for underlying tables versus XML functions in execution plans...................
Guideline: Name the default tables, so you recognize them in execution plans ......................
Guideline: Create an index on a column targeted by a predicate...............................................
Guideline: Create indexes on ordered collection tables ...............................................................
Guideline: Use XMLOptimizationCheck to determine why a query is not rewritten.............

9

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XML Schema Storage and Query: Advanced
Generating XML Schemas with DBMS_XMLSCHEMA.GENERATESCHEMA ........................ 9-1
Adding Unique Constraints to the Parent Element of an Attribute............................................... 9-3
Setting Annotation Attribute SQLInline to false for Out-Of-Line Storage ................................. 9-4
XPath Rewrite for Out-Of-Line Tables............................................................................................ 9-7
Storing Collections in Out-Of-Line Tables ......................................................................................... 9-8
Partitioning XMLType Tables and Columns Stored Object-Relationally.................................. 9-10
Examples of Partitioning XMLType Data ................................................................................... 9-11
Partition Maintenance .................................................................................................................... 9-12
Fully Qualified XML Schema URLs .................................................................................................. 9-13
Mapping XML Fragments to Large Objects (LOBs) ....................................................................... 9-14
complexType Extensions and Restrictions in Oracle XML DB .................................................... 9-15
complexType Declarations in XML Schema: Handling Inheritance ...................................... 9-15
Mapping complexType: simpleContent to Object Types.......................................................... 9-17
Mapping complexType: any and anyAttribute .......................................................................... 9-18
XML Schema: Working with Circular and Cyclical Dependencies............................................. 9-18
For Circular XML Schema Dependencies Set Parameter GENTABLES to TRUE ................. 9-19
complexType Declarations XML Schema: Handling Cycles .................................................... 9-19
How a complexType Can Reference Itself ........................................................................... 9-21
Cyclical References Among XML Schemas ................................................................................. 9-22
Support for Recursive Schemas.......................................................................................................... 9-24

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Sharing defaultTable Among Common Out-Of-Line Elements...............................................
Query Rewrite when DOCID is Present ......................................................................................
Disabling DOCID Column Creation ............................................................................................
Loading and Retrieving Large Documents with Collections .......................................................
Guidelines for Setting xdbcore Parameters.................................................................................

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XML Schema Evolution
Overview of XML Schema Evolution................................................................................................ 10-1
Using Copy-Based Schema Evolution............................................................................................... 10-2
Scenario for Copy-Based Evolution.............................................................................................. 10-2
copyEvolve Parameters and Errors .............................................................................................. 10-5
Limitations of Procedure COPYEVOLVE ................................................................................... 10-7
Guidelines for Using Procedure COPYEVOLVE ....................................................................... 10-8
Top-Level Element Name Changes....................................................................................... 10-8
User-Created Virtual Columns of Tables Other Than Default Tables ............................. 10-8
Ensure that the XML Schema and Dependents Are Not Used by Concurrent Sessions 10-8
Rollback When Procedure DBMS_XMLSCHEMA.COPYEVOLVE Raises an Error ..... 10-9
Failed Rollback From Insufficient Privileges ....................................................................... 10-9
Privileges Needed for XML Schema Evolution ................................................................... 10-9
Updating Existing XML Instance Documents using a Style Sheet ........................................ 10-10
Examples of Using Procedure COPYEVOLVE......................................................................... 10-12
Using In-Place XML Schema Evolution.......................................................................................... 10-15
Restrictions for In-Place XML Schema Evolution..................................................................... 10-15
Backward-Compatibility Restrictions ................................................................................. 10-15
Changes in Data Layout on Disk.................................................................................. 10-16
Reordering of XML Schema Constructs ...................................................................... 10-16
Changes from a Collection to a Non-Collection......................................................... 10-16
Model Changes within a complexType Element ....................................................... 10-16
Other Restrictions on In-Place Evolution ........................................................................... 10-17
Changes to Attributes in Namespace xdb................................................................... 10-17
Changes from a Non-Collection to a Collection......................................................... 10-17
Supported Operations for In-Place XML Schema Evolution.................................................. 10-17
Guidelines for Using In-Place XML Schema Evolution........................................................... 10-19
inPlaceEvolve Parameters............................................................................................................ 10-19
Creating the Document for the diffXML Parameter ................................................................ 10-20
diffXML Operations and Examples..................................................................................... 10-21

11

Transforming and Validating XMLType Data
Transforming XMLType Instances ....................................................................................................
SQL Function XMLTRANSFORM and XMLType Method TRANSFORM() .........................
XMLTRANSFORM and XMLType.transform(): Examples ...........................................................
Validating XMLType Instances ...........................................................................................................
Validating XML Data Stored as XMLType: Examples....................................................................

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Full-Text Search Over XML Data
Overview of Full-Text Search for XML ............................................................................................. 12-1

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Comparison of Full-Text Search and Other Search Types ........................................................
Searching XML Data .......................................................................................................................
Searching Documents using Full-Text Search and XML Structure .........................................
About the Full-Text Search Examples................................................................................................
Roles and Privileges........................................................................................................................
Schema and Data for Full-Text Search Examples.......................................................................
Overview of CONTAINS and ora:contains......................................................................................
Overview of SQL Function CONTAINS .....................................................................................
Overview of XPath Function ora:contains...................................................................................
Comparison of CONTAINS and ora:contains ............................................................................
CONTAINS SQL Function ..................................................................................................................
Full-Text Search using SQL Function CONTAINS ....................................................................
Full-Text Boolean Operators AND, OR, and NOT .............................................................
Full-Text Stemming: $ .............................................................................................................
Combining Boolean and Stemming Operators....................................................................
SCORE SQL Function .....................................................................................................................
Restricting the Scope of a CONTAINS Search............................................................................
WITHIN Structure Operator ..................................................................................................
Nested WITHIN................................................................................................................
WITHIN Attributes ..........................................................................................................
WITHIN and AND ...........................................................................................................
Definition of Section .........................................................................................................
INPATH Structure Operator ..................................................................................................
Text Path ............................................................................................................................
Text Path Compared to XPath ......................................................................................
Nested INPATH..............................................................................................................
HASPATH Structure Operator ............................................................................................
Projecting the CONTAINS Result ..............................................................................................
Indexing with a CONTEXT Index ..............................................................................................
Introduction to CONTEXT Indexes.....................................................................................
CONTEXT Index on XMLType Table..........................................................................
Maintaining a CONTEXT Index ...................................................................................
Roles and Privileges .......................................................................................................
Effect of a CONTEXT Index on CONTAINS .....................................................................
CONTEXT Index Preferences...............................................................................................
Making Search Case-Sensitive ......................................................................................
Introduction to Section Groups............................................................................................
Choosing a Section Group Type ...................................................................................
Choosing a Section Group .............................................................................................
ora:contains XQuery Function ..........................................................................................................
Full-Text Search using XQuery Function ora:contains ............................................................
Restricting the Scope of an ora:contains Query ........................................................................
Projecting the ora:contains Result...............................................................................................
Policies for ora:contains Queries.................................................................................................
Introduction to Policies for ora:contains Queries..............................................................
Policy Example: Supplied Stoplist ...............................................................................
Effect of Policies on ora:contains .........................................................................................

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Policy Example: User-Defined Lexer ...........................................................................
Policy Defaults........................................................................................................................
Performance of ora:contains ........................................................................................................
Use a Primary Filter in the Query........................................................................................
XPath Rewrite and CONTEXT Indexes ..............................................................................
Text Path BNF Specification..............................................................................................................
Support for Full-Text XML Examples..............................................................................................
Purchase-Order XML Document, po001.xml............................................................................
CREATE TABLE Statements .......................................................................................................
Purchase-Order XML Schema for Full-Text Search Examples ...............................................

Part III
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Using XMLType APIs

PL/SQL APIs for XMLType
Overview of PL/SQL APIs for XMLType.......................................................................................... 13-1
API Features..................................................................................................................................... 13-1
Lazy Loading of XML Data (Lazy Manifestation) .............................................................. 13-2
XMLType Data Type Supports XML Schema...................................................................... 13-2
XMLType Supports Data in Different Character Sets ........................................................ 13-2
PL/SQL DOM API for XMLType (DBMS_XMLDOM).................................................................. 13-3
Overview of the W3C Document Object Model (DOM) Recommendation ........................... 13-3
Oracle XML Developer's Kit Extensions to the W3C DOM Standard ............................. 13-3
Supported W3C DOM Recommendations ........................................................................... 13-3
Difference Between DOM and SAX ...................................................................................... 13-4
PL/SQL DOM API for XMLType (DBMS_XMLDOM): Features............................................ 13-4
XML Schema Support.............................................................................................................. 13-4
Enhanced Performance ........................................................................................................... 13-5
Designing End-to-End Applications using Oracle XML Developer's Kit and Oracle XML DB.....
13-5
Preparing XML Data to Use the PL/SQL DOM API for XMLType ....................................... 13-6
Defining an XML Schema Mapping to SQL Object Types........................................................ 13-6
DOM Fidelity for XML Schema Mapping ............................................................................ 13-7
Wrapping Existing Data into XML with XMLType Views....................................................... 13-7
DBMS_XMLDOM Methods Supported ....................................................................................... 13-7
PL/SQL DOM API for XMLType: Node Types ......................................................................... 13-8
Working with XML Schema-Based Data ..................................................................................... 13-9
DOM NodeList and NamedNodeMap Objects .......................................................................... 13-9
Using the PL/SQL DOM API for XMLType (DBMS_XMLDOM)......................................... 13-10
PL/SQL DOM API for XMLType – Examples.......................................................................... 13-10
Large Node Handling using DBMS_XMLDOM ...................................................................... 13-12
Get-Push Model............................................................................................................................. 13-14
Get-Pull Model .............................................................................................................................. 13-15
Set-Pull Model ............................................................................................................................... 13-16
Set-Push Model.............................................................................................................................. 13-17
Determining Binary Stream or Character Stream .................................................................... 13-19
PL/SQL Parser API for XMLType (DBMS_XMLPARSER).......................................................... 13-19
Features of the PL/SQL Parser API for XMLType................................................................... 13-19

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Using the PL/SQL Parser API for XMLType (DBMS_XMLPARSER) ..................................
PL/SQL XSLT Processor for XMLType (DBMS_XSLPROCESSOR) .........................................
Enabling Transformations and Conversions with XSLT.........................................................
PL/SQL XSLT Processor for XMLType: Features ....................................................................
Using the PL/SQL XSLT Processor API for XMLType (DBMS_XSLPROCESSOR) ...........
PL/SQL Translation API for XMLType (DBMS_XMLTRANSLATIONS)................................
DBMS_XMLTRANSLATIONS Methods ...................................................................................

14

PL/SQL Package DBMS_XMLSTORE
Overview of PL/SQL Package DBMS_XMLSTORE.......................................................................
Using Package DBMS_XMLSTORE..................................................................................................
Inserting with DBMS_XMLSTORE ..................................................................................................
Updating with DBMS_XMLSTORE..................................................................................................
Deleting with DBMS_XMLSTORE ...................................................................................................

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Java DOM API for XMLType
Overview of Java DOM API for XMLType ......................................................................................
Java DOM API for XMLType ..............................................................................................................
Accessing XMLType Data using JDBC ........................................................................................
Using XMLType Data with JDBC..........................................................................................
How Java Applications Use JDBC to Access XML Documents in Oracle XML DB.......
Manipulating XML Database Documents using JDBC .............................................................
Loading a Large XML Document into the Database using JDBC..............................................
Java DOM API for XMLType Features............................................................................................
Creating XML Schema-Based Documents.................................................................................
JDBC or SQLJ ..........................................................................................................................
Java DOM API for XMLType Classes..............................................................................................
Java Methods That Are Deprecated or Not Supported ...........................................................
Using the Java DOM API for XMLType ....................................................................................
Handling Large Nodes using Java ...................................................................................................
Stream Extensions to Java DOM .................................................................................................
Get-Pull Model .......................................................................................................................
Get-Push Model......................................................................................................................
Set-Pull Model ........................................................................................................................
Set-Push Model ......................................................................................................................
Using the Java DOM API and JDBC with Binary XML...............................................................

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Using the C API for XML
Overview of the C API for XML (Oracle XDK and Oracle XML DB) .........................................
Using OCI and the C API for XML with Oracle XML DB.............................................................
Accessing XMLType Data Stored in the Database.....................................................................
Creating XMLType Instances on the Client ................................................................................
XML Context Parameter for C DOM API Functions ......................................................................
OCIXmlDbInitXmlCtx() Syntax ....................................................................................................
OCIXmlDbFreeXmlCtx() Syntax...................................................................................................
Initializing and Terminating an XML Context ................................................................................

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Using the C API for XML with Binary XML .................................................................................... 16-6
Using the Oracle XML Developer's Kit Pull Parser with Oracle XML DB ................................ 16-9
Common XMLType Operations in C ............................................................................................... 16-14

17

Using Oracle Data Provider for .NET with Oracle XML DB
ODP.NET XML Support and Oracle XML DB................................................................................. 17-1
ODP.NET Sample Code........................................................................................................................ 17-1

Part IV
18

Viewing Existing Data as XML

Generating XML Data from the Database
Overview of Generating XML Data From Oracle Database .........................................................
Generating XML using SQL Functions.............................................................................................
XMLELEMENT and XMLATTRIBUTES SQL/XML Functions...............................................
Escaping Characters in Generated XML Data .....................................................................
Formatting of XML Dates and Timestamps.........................................................................
XMLElement Examples...........................................................................................................
XMLFOREST SQL/XML Function ..............................................................................................
XMLCONCAT SQL/XML Function ..........................................................................................
XMLAGG SQL/XML Function...................................................................................................
XMLPI SQL/XML Function ........................................................................................................
XMLCOMMENT SQL/XML Function ......................................................................................
XMLSERIALIZE SQL/XML Function .......................................................................................
XMLPARSE SQL/XML Function ...............................................................................................
XMLROOT Oracle SQL Function ...............................................................................................
XMLCOLATTVAL Oracle SQL Function ..................................................................................
XMLCDATA Oracle SQL Function ............................................................................................
Generating XML using DBMS_XMLGEN .....................................................................................
Using PL/SQL Package DBMS_XMLGEN ...............................................................................
Functions and Procedures of Package DBMS_XMLGEN .......................................................
DBMS_XMLGEN Examples ........................................................................................................
SYS_XMLGEN Oracle SQL Function..............................................................................................
Advantages of using Oracle SQL Function SYS_XMLGEN ...................................................
Using XMLFormat Object Type ..................................................................................................
SYS_XMLAGG Oracle SQL Function .............................................................................................
Guidelines for Generating XML with Oracle XML DB...............................................................
Ordering Query Results Before Aggregating, using XMLAGG ORDER BY Clause ..........
Returning a Rowset using XMLTABLE .....................................................................................

19

XMLType Views
What Are XMLType Views?.................................................................................................................
Creating XMLType Views: Syntax ...............................................................................................
Creating Non-Schema-Based XMLType Views ...............................................................................
Creating Non-Schema-Based XMLType Views using SQL/XML Publishing Functions ....
Creating Non-Schema-Based XMLType Views using Object Types and SYS_XMLGEN....
Creating XML Schema-Based XMLType Views ..............................................................................

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Creating XML Schema-Based XMLType Views using SQL/XML Publishing Functions....
Using Namespaces with SQL/XML Publishing Functions ...............................................
Creating XML Schema-Based XMLType Views using Object Types or Object Views .......
Creating XMLType Employee View, with Nested Department Information...............
Step 1. Create Object Types ..........................................................................................
Step 2. Create and Register XML Schema emp_complex.xsd ..................................
Step 3a. Create XMLType View emp_xml using Object Type emp_t .....................
Step 3b. Create XMLType View emp_xml using Object View emp_v ...................
Creating XMLType Department View, with Nested Employee Information...............
Step 1. Create Object Types ..........................................................................................
Step 2. Register XML Schema dept_complex.xsd ......................................................
Step 3a. Create XMLType View dept_xml using Object Type dept_t ....................
Step 3b. Create XMLType View dept_xml using Relational Data Directly ...........
Creating XMLType Views from XMLType Tables.........................................................................
Referencing XMLType View Objects using SQL Function REF ................................................
DML (Data Manipulation Language) on XMLType Views.........................................................

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Accessing Data Through URIs
Overview of Oracle XML DB URL Features ....................................................................................
URIs and URLs ......................................................................................................................................
URIType and its Subtypes ..................................................................................................................
DBUris and XDBUris – What For?................................................................................................
URIType Methods...........................................................................................................................
HTTPURIType PL/SQL Method GETCONTENTTYPE() .................................................
DBURIType PL/SQL Method GETCONTENTTYPE() ......................................................
DBURIType PL/SQL Method GETCLOB() .........................................................................
DBURIType PL/SQL Method GETBLOB()..........................................................................
Accessing Data using URIType Instances ........................................................................................
XDBUris: Pointers to Repository Resources ..................................................................................
XDBUri URI Syntax ......................................................................................................................
XDBUri Examples .........................................................................................................................
DBUris: Pointers to Database Data..................................................................................................
Viewing the Database as XML Data ...........................................................................................
DBUri URI Syntax .........................................................................................................................
DBUris are Scoped to a Database and Session..........................................................................
DBUri Examples ............................................................................................................................
Targeting a Table....................................................................................................................
Targeting a Row in a Table...................................................................................................
Targeting a Column...............................................................................................................
Retrieving the Text Value of a Column ..............................................................................
Targeting a Collection ...........................................................................................................
Creating New Subtypes of URIType using Package URIFACTORY .......................................
Registering New URIType Subtypes with Package URIFACTORY .....................................
SYS_DBURIGEN SQL Function ......................................................................................................
Rules for Passing Columns or Object Attributes to SYS_DBURIGEN ..................................
SYS_DBURIGEN SQL Function: Examples...............................................................................
Returning Partial Results ......................................................................................................

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RETURNING URLs to Inserted Objects .............................................................................
DBUriServlet ........................................................................................................................................
Overriding the MIME Type using a URL ..................................................................................
Customizing DBUriServlet ..........................................................................................................
DBUriServlet Security...................................................................................................................
Configuring Package URIFACTORY to Handle DBUris ........................................................

Part V
21

Oracle XML DB Repository

Accessing Oracle XML DB Repository Data
Overview of Oracle XML DB Repository .........................................................................................
Two Ways to Access Oracle XML DB Repository Resources ...................................................
Repository Terminology and Supplied Resources .........................................................................
Repository Terminology ................................................................................................................
Supplied Files and Folders.............................................................................................................
Oracle XML DB Repository Resources .............................................................................................
Where Is Repository Data Stored?................................................................................................
Names of Generated Tables ...................................................................................................
Defining Structured Storage for Resources..........................................................................
Oracle ASM Virtual Folder.....................................................................................................
Path-Name Resolution....................................................................................................................
Link Types........................................................................................................................................
Repository and Document Links ...........................................................................................
Hard Links and Weak Links ..................................................................................................
Creating a Weak Link with No Knowledge of Folder Hierarchy.....................................
Restricting Multiple Hard Links............................................................................................
Navigational or Path Access to Repository Resources ...................................................................
Accessing Oracle XML DB Resources using Internet Protocols.............................................
Where You Can Use Oracle XML DB Protocol Access.....................................................
Using Protocol Access ...........................................................................................................
Retrieving Oracle XML DB Resources ................................................................................
Storing Oracle XML DB Resources......................................................................................
Using Internet Protocols and XMLType: XMLType Direct Stream Write.....................
Accessing Oracle ASM Files using Protocols and Resource APIs – For DBAs ....................
Query-Based Access to Repository Resources ...............................................................................
Servlet Access to Repository Resources..........................................................................................
Operations on Repository Resources ..............................................................................................

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Configuring Oracle XML DB Repository
Resource Configuration Files Configure a Resource ....................................................................
Configuring a Resource........................................................................................................................
Common Configuration Parameters..................................................................................................
Configuration Element ResConfig................................................................................................
Configuration Element defaultChildConfig ...............................................................................
Configuration Element applicationData......................................................................................

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23

Using XLink and XInclude with Oracle XML DB
Overview of XLink and XInclude ......................................................................................................
XLink and XInclude Link Types.........................................................................................................
XLink and XInclude Links Model Document Relationships ....................................................
XLink and XInclude Link Types ...................................................................................................
XInclude: Compound Documents......................................................................................................
Using XLink with Oracle XML DB ....................................................................................................
Using XInclude with Oracle XML DB...............................................................................................
Expanding Compound-Document Inclusions ............................................................................
Validating Compound Documents ..............................................................................................
Updating Compound Documents ................................................................................................
Versioning, Locking, and Controlling Access to Compound Documents..............................
Examining XLink and XInclude Links using DOCUMENT_LINKS View ...............................
Querying DOCUMENT_LINKS for XLink Information ...........................................................
Querying DOCUMENT_LINKS for XInclude Information ......................................................
Configuring Resources for XLink and XInclude.............................................................................
Configuring Treatment of Unresolved Links: UnresolvedLink Attribute..............................
Configuring the Document Links to Create: LinkType Element ...........................................
Configuring the Path Format for Retrieval: PathFormat Element .........................................
Configuring Conflict-Resolution for XInclude: ConflictRule Element .................................
Configuring Decomposition of Documents using XInclude: SectionConfig Element........
XLink and XInclude Configuration Examples..........................................................................
Managing XLink and XInclude Links using DBMS_XDB.processLinks.................................

24

Managing Resource Versions
Overview of Oracle XML DB Versioning .........................................................................................
Versioning and Resource IDs..............................................................................................................
Versioning and ACLs............................................................................................................................
Resource Versioning Examples...........................................................................................................

25

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Accessing the Repository using RESOURCE_VIEW and PATH_VIEW
Overview of Oracle XML DB RESOURCE_VIEW and PATH_VIEW ........................................
RESOURCE_VIEW Definition and Structure .............................................................................
PATH_VIEW Definition and Structure........................................................................................
Understanding the Difference Between RESOURCE_VIEW and PATH_VIEW...................
Operations You Can Perform using UNDER_PATH and EQUALS_PATH..........................
RESOURCE_VIEW and PATH_VIEW SQL Functions .................................................................
UNDER_PATH SQL Function ......................................................................................................
EQUALS_PATH SQL Function.....................................................................................................
PATH SQL Function .......................................................................................................................
DEPTH SQL Function.....................................................................................................................
Using RESOURCE_VIEW and PATH_VIEW SQL Functions ......................................................
Accessing Repository Data Paths, Resources and Links: Examples........................................
Deleting Repository Resources: Examples ................................................................................
Deleting Nonempty Folder Resources................................................................................
Updating Repository Resources: Examples ..............................................................................

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Working with Multiple Oracle XML DB Resources..................................................................... 25-18
Performance Tuning of Oracle XML DB Repository Operations .............................................. 25-19
Searching for Resources using Oracle Text .................................................................................... 25-20

26

Accessing the Repository using PL/SQL
Overview of PL/SQL Package DBMS_XDB.....................................................................................
DBMS_XDB: Resource Management ................................................................................................
DBMS_XDB: ACL-Based Security Management ............................................................................
DBMS_XDB: Configuration Management.......................................................................................

27

Repository Access Control
Access Control Concepts......................................................................................................................
Principal: A User or Role................................................................................................................
Database Roles Map Database Privileges to Users .............................................................
Principal DAV::owner .............................................................................................................
Privilege: A Permission ..................................................................................................................
Access Control Entry (ACE) ..........................................................................................................
Access Control List (ACL) .............................................................................................................
Database Privileges for Repository Operations ..............................................................................
Privileges.................................................................................................................................................
Atomic Privileges ............................................................................................................................
Aggregate Privileges.......................................................................................................................
ACLs and ACEs......................................................................................................................................
System ACLs....................................................................................................................................
ACL and ACE Evaluation..............................................................................................................
ACL Validation................................................................................................................................
ACL Inheritance ..............................................................................................................................
Complementing the Principals in an ACE: Element invert ....................................................
ACE Validity Time Period ...........................................................................................................
Working with Access Control Lists (ACLs)....................................................................................
Creating an ACL using DBMS_XDB.CREATERESOURCE....................................................
Retrieving an ACL Document, Given its Repository Path......................................................
Setting the ACL of a Resource.....................................................................................................
Deleting an ACL............................................................................................................................
Updating an ACL ..........................................................................................................................
Retrieving the ACL Document that Protects a Given Resource.............................................
Retrieving Privileges Granted to the Current User for a Particular Resource .....................
Checking Whether the Current User Has Privileges on a Resource......................................
Checking Whether a User Has Privileges using the ACL and Resource Owner.................
Retrieving the Path of the ACL that Protects a Given Resource ............................................
Retrieving the Paths of All Resources Protected by a Given ACL.........................................
ACL Caching ........................................................................................................................................
Repository Resources and Database Table Security.....................................................................
Optimization: Do not enforce acl-based security if you do not need it ................................
Integrating Oracle XML DB with LDAP.........................................................................................

xxii

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28

Accessing the Repository using Protocols
Overview of Oracle XML DB Protocol Server .................................................................................
Session Pooling ................................................................................................................................
Oracle XML DB Protocol Server Configuration Management.....................................................
Configuring Protocol Server Parameters.....................................................................................
Configuring Secure HTTP (HTTPS) .............................................................................................
Enable the HTTP Listener to Use SSL ...................................................................................
Enable TCPS Dispatcher .........................................................................................................
Interaction with Oracle XML DB File-System Resources..........................................................
Protocol Server Handles XML Schema-Based or Non-Schema-Based XML Documents.....
Event-Based Logging......................................................................................................................
Using FTP and Oracle XML DB Protocol Server.............................................................................
Oracle XML DB Protocol Server: FTP Features ..........................................................................
FTP Features That Are Not Supported .................................................................................
Supported FTP Client Methods .............................................................................................
FTP Quote Methods...............................................................................................................
Using FTP with Oracle ASM Files .......................................................................................
Using FTP on the Standard Port Instead of the Oracle XML DB Default Port .............
Using IPv6 IP Addresses with FTP .....................................................................................
FTP Server Session Management.........................................................................................
Handling Error 421. Modifying the Default Timeout Value of an FTP Session ...........
FTP Client Failure in Passive Mode ....................................................................................
Using HTTP(S) and Oracle XML DB Protocol Server ..................................................................
Oracle XML DB Protocol Server: HTTP(S) Features ................................................................
HTTP(S) Features That Are Not Supported.......................................................................
Supported HTTP(S) Client Methods ...................................................................................
Using HTTP(S) on a Standard Port Instead of an Oracle XML DB Default Port..........
Using IPv6 IP Addresses with HTTP(S) .............................................................................
HTTPS: Support for Secure HTTP .......................................................................................
Controlling URL Expiration Time .......................................................................................
Anonymous Access to Oracle XML DB Repository using HTTP ...................................
Using Java Servlets with HTTP(S).......................................................................................
Embedded PL/SQL Gateway ..............................................................................................
Sending Multibyte Data From a Client...............................................................................
Characters That Are Not ASCII in URLs............................................................................
Controlling Character Sets for HTTP(S) .............................................................................
Request Character Set ....................................................................................................
Response Character Set..................................................................................................
Using WebDAV and Oracle XML DB..............................................................................................
Oracle XML DB WebDAV Features ...........................................................................................
WebDAV Features That Are Not Supported .....................................................................
Supported WebDAV Client Methods .................................................................................
Using WebDAV with Microsoft Windows XP SP2 ..................................................................
Creating a WebFolder in Microsoft Windows using Oracle XML DB and WebDAV ........

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29

User-Defined Repository Metadata
Overview of Metadata and XML ........................................................................................................
Kinds of Metadata – Uses of the Term .........................................................................................
User-Defined Resource Metadata .................................................................................................
Scenario: Metadata for a Photo Collection ..................................................................................
XML Schemas to Define Resource Metadata...................................................................................
Adding, Updating, and Deleting Resource Metadata ....................................................................
Adding Metadata using APPENDRESOURCEMETADATA...................................................
Deleting Metadata using DELETERESOURCEMETADATA...................................................
Adding Metadata using SQL DML ..............................................................................................
Adding Metadata using WebDAV PROPPATCH .....................................................................
Querying XML Schema-Based Resource Metadata ........................................................................
XML Image Metadata from Binary Image Metadata....................................................................
Adding Non-Schema-Based Resource Metadata ..........................................................................
PL/SQL Procedures Affecting Resource Metadata .......................................................................

30

Oracle XML DB Repository Events
Overview of Repository Events..........................................................................................................
Repository Events: Use Cases........................................................................................................
Repository Events and Database Triggers...................................................................................
Repository Event Listeners and Event Handlers........................................................................
Repository Event Configuration ...................................................................................................
Possible Repository Events .................................................................................................................
Repository Operations and Events ....................................................................................................
Repository Event Handler Considerations.......................................................................................
Configuring Repository Events ..........................................................................................................
Configuration Element event-listeners ........................................................................................
Configuration Element listener .....................................................................................................
Repository Events Configuration Examples ...............................................................................

31

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Using Oracle XML DB Content Connector
Overview of JCR and Oracle XML DB Content Connector ..........................................................
About the Content Repository API for Java (JCR) .....................................................................
About Oracle XML DB Content Connector.................................................................................
How Oracle XML DB Repository Is Exposed in JCR .....................................................................
Example of How Files and Folders are Exposed in JCR............................................................
Oracle Extensions to JCR Node Types .........................................................................................
Binary and XML Content ...............................................................................................................
System-Defined Metadata..............................................................................................................
User-Defined Metadata ..................................................................................................................
Hard Links and Weak Links..........................................................................................................
How to Use Oracle XML DB Content Connector............................................................................
Setting CLASSPATH ......................................................................................................................
Obtaining the JCR Repository Object...........................................................................................
Sample Code to Upload File ..........................................................................................................
Additional Code Samples ..............................................................................................................

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Logging API for Oracle XML DB Content Connector ...............................................................
Supported JCR Compliance Levels ............................................................................................
Oracle XML DB Content Connector Restrictions .....................................................................
Default Workspace Name.....................................................................................................
Operations Restricted to Specific Node Types ..................................................................
Determining the State of Files or Folders ...........................................................................
Interaction Between Binary and XML Content .................................................................
Order in Which Changes Are Saved ...................................................................................
Undefined Properties ............................................................................................................
Node Type nt:base Is Abstract .............................................................................................
Node jcr:content Is Created Automatically........................................................................
Saving Normalizes Node jcr:xmltext ..................................................................................
Node Type mix:referenceable ..............................................................................................
Full-Text Indexing..................................................................................................................
Using XML Schemas with JCR .........................................................................................................
Why Register XML Schemas for Use with JCR?.......................................................................
How to Register an XML Schema with JCR ..............................................................................
How JCR Node Types are Generated from XML Schemas.....................................................
Built-In Simple Types ............................................................................................................
XML Schema-Defined Simple Types ..................................................................................
Complex Types.......................................................................................................................
Global Element Declarations................................................................................................

32

Writing Oracle XML DB Applications in Java
Overview of Oracle XML DB Java Applications.............................................................................
Which Oracle XML DB APIs Are Available Inside and Outside the Database?....................
Design Guidelines: Java Inside or Outside the Database? ...........................................................
HTTP(S): Accessing Java Servlets or Directly Accessing XMLType Resources.....................
Accessing Many XMLType Object Elements: Use JDBC XMLType Support ........................
Use the Servlets to Manipulate and Write Out Data Quickly as XML....................................
Writing Oracle XML DB HTTP Servlets in Java..............................................................................
Configuring Oracle XML DB Servlets ..............................................................................................
HTTP Request Processing for Oracle XML DB Servlets ...............................................................
Session Pool and Oracle XML DB Servlets ......................................................................................
Native XML Stream Support...............................................................................................................
Oracle XML DB Servlet APIs ..............................................................................................................
Oracle XML DB Servlet Example .......................................................................................................

33

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32-7

Using Native Oracle XML DB Web Services
Overview of Native Oracle XML DB Web Services........................................................................
Configuring and Enabling Web Services for Oracle XML DB .....................................................
Configuring Web Services for Oracle XML DB ..........................................................................
Enabling Web Services for Specific Users....................................................................................
Querying Oracle XML DB using a Web Service..............................................................................
Accessing PL/SQL Stored Procedures using a Web Service .........................................................
Example of Using a PL/SQL Function with a Web Service .....................................................

33-1
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xxv

Part VI
34

Oracle Tools that Support Oracle XML DB

Administering Oracle XML DB
Installing Oracle XML DB ...................................................................................................................
Installing Oracle XML DB with Database Configuration Assistant .......................................
Dynamic Protocol Registration of FTP and HTTP(S) Services with Local Listener.......
Changing FTP or HTTP(S) Port Numbers ....................................................................
Post-installation.................................................................................................................
Installing Oracle XML DB Manually without DBCA ................................................................
Post-Installation........................................................................................................................
Upgrading an Existing Oracle XML DB Installation......................................................................
Validation of ACL Documents and Configuration File.............................................................
Administering Oracle XML DB using Oracle Enterprise Manager.............................................
Configuring Oracle XML DB using xdbconfig.xml........................................................................
Oracle XML DB Configuration File, xdbconfig.xml...................................................................
 (Top-Level Element).........................................................................................
 (Child of ) .....................................................................................
 (Child of ) ...................................................................................
 (Child of ) .............................................................................
 (Child of )............................................................................
 (Descendant of )...............................................................................
Oracle XML DB Configuration File Example ......................................................................
Oracle XML DB Configuration API.....................................................................................
Configuring Default Namespace to Schema Location Mappings ..................................
Configuring XML File Extensions .......................................................................................
Package DBMS_XDB_ADMIN.........................................................................................................

35

Loading XML Data using SQL*Loader
Overview of Loading XMLType Data Into Oracle Database ........................................................
Loading XMLType Data using SQL*Loader ....................................................................................
Loading XMLType Data in LOBs using SQL*Loader................................................................
Loading LOB Data in Predetermined Size Fields................................................................
Loading LOB Data in Delimited Fields ................................................................................
Loading XML Columns Containing LOB Data from LOBFILEs.......................................
Specifying LOBFILEs...............................................................................................................
Loading XMLType Data Directly from a Control File using SQL*Loader .............................
Loading Large XML Documents into Oracle Database .................................................................

36

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Exporting and Importing XMLType Tables
Overview of Oracle Data Pump..........................................................................................................
EXPORT/IMPORT Support in Oracle XML DB .............................................................................
Exporting XML Schema-Based XMLType Tables ...........................................................................
Exporting Hierarchy-Enabled (Repository) Tables.........................................................................
Exporting and Importing Transportable Tablespaces ....................................................................
Repository Resources and Foldering Support.................................................................................
Full Database Export.......................................................................................................................

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Exporting and Importing with Different Character Sets ..........................................................
Export/Import Syntax and Examples ................................................................................................
Performing a Table-Mode Export /Import .................................................................................
Performing a Schema-Mode Export/Import ..............................................................................

37

Exchanging XML Data using Oracle Streams AQ
How Do AQ and XML Complement Each Other? ..........................................................................
AQ and XML Message Payloads ..................................................................................................
Advantages of Using AQ ...............................................................................................................
Oracle Streams and AQ ........................................................................................................................
Streams Message Queuing.............................................................................................................
XMLType Attributes in Object Types................................................................................................
Internet Data Access Presentation (iDAP)........................................................................................
iDAP Architecture .................................................................................................................................
XMLType Queue Payloads............................................................................................................
Guidelines for Using XML and Oracle Streams Advanced Queuing .........................................
Storing Oracle Streams AQ XML Messages with Many PDFs as One Record?.....................
Adding New Recipients After Messages Are Enqueued ..........................................................
Enqueuing and Dequeuing XML Messages? ..............................................................................
Parsing Messages with XML Content from Oracle Streams AQ Queues ...............................
Preventing the Listener from Stopping Until the XML Document Is Processed...................
Using HTTPS with AQ ...................................................................................................................
Storing XML in Oracle Streams AQ Message Payloads ............................................................
Comparing iDAP and SOAP .........................................................................................................

Part VII
A

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Appendixes

Oracle-Supplied XML Schemas and Examples
XDBResource.xsd: XML Schema for Oracle XML DB Resources ..................................................
XDBResource.xsd .............................................................................................................................
XDBResConfig.xsd: XML Schema for Resource Configuration ....................................................
XDBResConfig.xsd ............................................................................................................................
acl.xsd: XML Schema for ACLs...........................................................................................................
acl.xsd................................................................................................................................................
xdbconfig.xsd: XML Schema for Configuring Oracle XML DB...................................................
xdbconfig.xsd...................................................................................................................................
xdiff.xsd: XML Schema for Comparing Schemas for In-Place Evolution ..................................
xdiff.xsd ............................................................................................................................................
Purchase-Order XML Schemas ...........................................................................................................
XSL Style Sheet Example, PurchaseOrder.xsl..................................................................................
Loading XML Data using C (OCI) .....................................................................................................
Initializing and Terminating an XML Context (OCI).....................................................................

B

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A-47

Oracle XML DB Restrictions

Index

xxvii

List of Examples
1–1
3–1
3–2
3–3
3–4
3–5
3–6
3–7
3–8
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3–10
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3–37
3–38
3–39
3–40
3–41
3–42
3–43
3–44
3–45
3–46
3–47
3–48
3–49
3–50
3–51
3–52
3–53
xxviii

Listener Status with FTP and HTTP(S) Protocol Support Enabled .................................. 1-10
Creating a Table with an XMLType Column.......................................................................... 3-3
Creating a Table of XMLType ................................................................................................... 3-3
Partitioning a Binary XML Table using Virtual Columns ................................................... 3-4
Creating a Database Directory .................................................................................................. 3-6
Inserting XML Content into an XMLType Table.................................................................... 3-6
Inserting Content into an XMLType Table using Java .......................................................... 3-6
Inserting Content into an XMLType Table using C............................................................... 3-7
Inserting XML Content into the Repository using CREATERESOURCE ....................... 3-10
Purchase-Order XML Schema, purchaseOrder.xsd............................................................ 3-14
Annotated Purchase-Order XML Schema, purchaseOrder.xsd ........................................ 3-20
Registering an XML Schema using DBMS_XMLSCHEMA.REGISTERSCHEMA......... 3-25
Objects Created During XML Schema Registration............................................................ 3-25
Creating an XMLType Table that Conforms to an XML Schema ..................................... 3-28
Creating an XMLType Table for Nested Collections.......................................................... 3-29
Using DESCRIBE with an XML Schema-Based XMLType Table ..................................... 3-29
Error From Attempting to Insert an Incorrect XML Document........................................ 3-32
Error When Inserting Incorrect XML Document (Partial Validation) ............................. 3-32
Forcing Full XML Schema Validation using a CHECK Constraint .................................. 3-33
Enforcing Full XML Schema Validation using a BEFORE INSERT Trigger ................... 3-34
Constraining a Binary XML Table using a Virtual Column .............................................. 3-35
Integrity Constraints and Triggers for an XMLType Table Stored Object-Relationally 3-35
Enforcing Database Integrity When Loading XML using FTP ......................................... 3-36
PurchaseOrder XML Instance Document............................................................................. 3-38
Retrieving an Entire XML Document using OBJECT_VALUE ......................................... 3-39
Accessing XML Fragments using XMLQUERY .................................................................. 3-40
Accessing a Text Node Value using XMLCAST and XMLQuery..................................... 3-41
Searching XML Content using XMLExists, XMLCast, and XMLQuery .......................... 3-42
Finding the Reference for a Purchase Order using XMLQuery and XMLExists............ 3-45
Accessing Description Nodes using XMLTABLE ............................................................... 3-46
Counting the Number of Elements in a Collection using XMLTABLE ........................... 3-47
Counting the Number of Child Elements in an Element using XMLTABLE ................. 3-48
Creating a Relational View of XML Content ....................................................................... 3-49
Accessing Individual Members of a Collection using a View........................................... 3-50
Querying XML Data using Views ......................................................................................... 3-51
Business-Intelligence Query of XML Data using a View ................................................... 3-52
Updating XML Content using UPDATEXML ..................................................................... 3-53
Replacing an Entire Element using UPDATEXML............................................................. 3-53
Incorrectly Updating a Node That Occurs Multiple Times in a Collection .................... 3-54
Correctly Updating a Node That Occurs Multiple Times in a Collection ....................... 3-55
Changing Text Node Values using UPDATEXML ............................................................. 3-56
Generating XML Data using SQL/XML Functions ............................................................ 3-59
Creating XMLType Views Over Conventional Relational Tables .................................... 3-60
Querying XMLType Views..................................................................................................... 3-61
Generating XML Data from a Relational Table using DBURIType and getXML()........ 3-63
Restricting Rows using an XPath Predicate ......................................................................... 3-64
Restricting Rows and Columns using an XPath Predicate ................................................ 3-64
XSLT Style Sheet Example: PurchaseOrder.xsl ................................................................... 3-65
Applying a Style Sheet using TRANSFORM....................................................................... 3-67
Uploading Content to the Repository using FTP ................................................................ 3-70
Creating a Text Document Resource using CREATERESOURCE ................................... 3-72
Creating Folders using PL/SQL Package DBMS_XDB ...................................................... 3-74
Accessing a Text Document in the Repository using XDBURITYPE ............................... 3-75
Accessing Resource Content using RESOURCE_VIEW..................................................... 3-75

3–54
3–55
3–56
3–57
3–58
3–59
3–60
3–61
3–62
3–63
3–64
3–65
3–66
3–67
4–1
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4–3
4–4
4–5
4–6
4–7
4–8
4–9
4–10
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5–11
5–12
5–13
5–14
5–15
5–16
5–17
5–18
5–19

Accessing XML Documents using Resource and Namespace Prefixes ........................... 3-75
Querying Repository Resource Data using SQL Function REF and Element XMLRef. 3-76
Selecting XML Document Fragments Based on Metadata, Path, and Content............... 3-77
Updating a Document using UPDATE and UPDATEXML on the Resource ................. 3-78
Updating a Node using UPDATE and UPDATEXML....................................................... 3-79
Updating XML Schema-Based Documents in the Repository .......................................... 3-80
Viewing RESOURCE_VIEW and PATH_VIEW Structures............................................... 3-82
Accessing Resources using EQUALS_PATH and RESOURCE_VIEW............................ 3-83
Determining the Path to XSL Style Sheets Stored in the Repository................................ 3-84
Counting Resources Under a Path ........................................................................................ 3-84
Listing the Folder Contents in a Path.................................................................................... 3-84
Listing the Links Contained in a Folder ............................................................................... 3-85
Finding Paths to Resources that Contain Purchase-Order XML Documents ................. 3-85
Execution Plan Output for a Folder-Restricted Query ....................................................... 3-86
Finding a Node using SQL/XML Function XMLExists ........................................................ 4-4
Extracting the Scalar Value of an XML Fragment using XMLCAST................................... 4-5
Querying XMLTYPE Data ......................................................................................................... 4-6
Querying Transient XMLTYPE Data using a PL/SQL Cursor .......................................... 4-7
Extracting XML Data using XMLTABLE, and Inserting It into a Database Table ............ 4-7
Extracting XML Data and Inserting It into a Table using a PL/SQL Procedure ............... 4-9
Searching XML Data using SQL/XML Functions.................................................................. 4-9
Extracting Fragments from an XMLTYPE Instance using XMLQUERY ......................... 4-10
Updating XMLType Data using a SQL UPDATE Statement ............................................ 4-11
Updating XMLTYPE using UPDATE and UPDATEXML................................................. 4-15
Updating Multiple Text Nodes and Attribute Values using UPDATEXML .................. 4-15
Updating Selected Nodes within a Collection using UPDATEXML ............................... 4-16
NULL Updates with UPDATEXML – Element and Attribute .......................................... 4-18
NULL Updates with UPDATEXML – Text Node ............................................................... 4-19
XPath Expressions in UPDATEXML Expression ................................................................ 4-21
Object Relational Equivalent of UPDATEXML Expression............................................... 4-21
Creating a View using UPDATEXML .................................................................................. 4-22
Inserting a LineItem Element into a LineItems Element.................................................... 4-24
Inserting an Element that Uses a Namespace...................................................................... 4-25
Inserting a LineItem Element Before the First LineItem ELement ................................... 4-28
Inserting a Date Element as the Last Child of an Action Element.................................... 4-31
Deleting LineItem Element Number 222.............................................................................. 4-32
Creating Resources for Examples .......................................................................................... 5-15
XMLQuery Applied to a Sequence of Items of Different Types ....................................... 5-16
FLOWR Expression using for, let, order by, where, and return ....................................... 5-17
FLOWR Expression using Built-In Functions...................................................................... 5-18
Querying Relational Tables as XML...................................................................................... 5-19
Using Relational Data in a Nested FLWOR Query............................................................. 5-20
Querying a Relational Table as XML using XMLTable...................................................... 5-22
Querying an XMLType Column using XMLQuery PASSING Clause ............................ 5-23
Using XMLTABLE with XML Schema-Based Data ............................................................ 5-24
Using XMLQUERY with Schema-Based Data ..................................................................... 5-25
Using XMLTABLE with PASSING and COLUMNS Clauses ........................................... 5-25
Decomposing XML Collection Elements into Relational Data using XMLTABLE........ 5-27
Using XMLQUERY with a Namespace Declaration........................................................... 5-28
Using XMLTABLE with the XMLNAMESPACES Clause................................................. 5-29
Optimization of XMLQuery over Relational Data.............................................................. 5-31
Optimization of XMLTable over Relational Data ............................................................... 5-32
Optimization of XMLQuery with Schema-Based XMLType Data ................................... 5-32
Optimization of XMLTable with Schema-Based XMLType Data..................................... 5-33
Unoptimized Repository Query using fn:doc ..................................................................... 5-36

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5–20
5–21
5–22
5–23
5–24
5–25
5–26
5–27
6–1
6–2
6–3
6–4
6–5
6–6
6–7
6–8
6–9
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6–13
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6–20
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6–23
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6–29
6–30
6–31
6–32
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6–36
6–37
6–38
6–39
6–40
6–41
7–1
7–2
7–3
7–4
7–5
7–6

xxx

Optimized Repository Query using EQUALS_PATH ....................................................... 5-36
Repository Query using Oracle XQuery Pragma ora:defaultTable.................................. 5-37
Static Type-Checking of XQuery Expressions: oradb URI scheme .................................. 5-37
Static Type-Checking of XQuery Expressions: Schema-Based XML................................ 5-38
Using the SQL*Plus XQUERY Command ............................................................................ 5-38
Using XQuery with PL/SQL .................................................................................................. 5-39
Using XQuery with JDBC ....................................................................................................... 5-40
Using XQuery with ODP.NET and C# ................................................................................. 5-41
CREATE INDEX using XMLCAST and XMLQUERY on a Singleton Element................. 6-6
CREATE INDEX using EXTRACTVALUE on a Singleton Element ................................... 6-6
Making Query Data Compatible with Index Data – SQL Cast ......................................... 6-12
Making Query Data Compatible with Index Data – XQuery Cast ................................... 6-12
Path Table Contents for Two Purchase Orders ................................................................... 6-14
Creating an XMLIndex Index on XMLType Unstructured Storage ................................. 6-18
Obtaining the Name of an XMLIndex Index on a Particular Table.................................. 6-18
Renaming and Dropping an XMLIndex Index.................................................................... 6-18
Naming the Path Table of an XMLIndex Index................................................................... 6-19
Determining the System-Generated Name of an XMLIndex Path Table ........................ 6-19
Specifying Storage Options When Creating an XMLIndex Index .................................... 6-20
Dropping an XMLIndex Unstructured Component ........................................................... 6-20
Determining the Names of the Secondary Indexes of an XMLIndex Index.................... 6-20
Creating a Function-Based Index on Path-Table Column VALUE .................................. 6-21
Trying to Create a Numeric Index on Path-Table Column VALUE Directly ................. 6-21
Creating a Numeric Index on Column VALUE with Procedure createNumberIndex . 6-21
Creating a Date Index on Column VALUE with Procedure createDateIndex ............... 6-21
Creating an Oracle Text CONTEXT Index on Path-Table Column VALUE ................... 6-22
Showing All Secondary Indexes on an XMLIndex Path Table ......................................... 6-22
XMLIndex Index: Adding a Structured Component.......................................................... 6-23
Dropping an XMLIndex Structured Component ................................................................ 6-24
Creating a B-Tree Index on an XMLIndex Index Content Table....................................... 6-24
Oracle Text CONTEXT Index on an XMLIndex Index Content Table............................. 6-24
XMLIndex with Only a Structured Component and using Namespaces........................ 6-24
Checking Whether an XMLIndex Unstructured Component Is Used............................. 6-26
Obtaining the Name of an XMLIndex Index from Its Path-Table Name ........................ 6-27
Extracting Data from an XML Fragment using XMLIndex ............................................... 6-27
Using a Structured XMLIndex Component for a Query with Two Predicates .............. 6-28
Using a Structured XMLIndex Component for a Query with Multilevel Chaining ...... 6-29
Turning Off XMLIndex using Optimizer Hints .................................................................. 6-30
XMLIndex Path Subsetting with CREATE INDEX............................................................. 6-31
XMLIndex Path Subsetting with ALTER INDEX................................................................ 6-32
XMLIndex Path Subsetting using a Namespace Prefix ...................................................... 6-32
Creating an XMLIndex Index in Parallel.............................................................................. 6-34
Using Different PARALLEL Degrees for XMLIndex Internal Objects............................. 6-35
Specifying Deferred Synchronization for XMLIndex ......................................................... 6-36
Manually Synchronizing an XMLIndex Index using SYNCINDEX................................. 6-36
Automatic Collection of Statistics on XMLIndex Objects .................................................. 6-37
Creating an Oracle Text Index ............................................................................................... 6-46
Searching XML Data using SQL Function CONTAINS ..................................................... 6-46
Using an Oracle Text Index and an XMLIndex Index ........................................................ 6-47
XML Schema Instance purchaseOrder.xsd ............................................................................ 7-2
purchaseOrder.xml: Document That Conforms to purchaseOrder.xsd ............................. 7-3
Registering an XML Schema using DBMS_XMLSCHEMA.REGISTERSCHEMA............ 7-7
Creating SQL Object Types to Store XMLType Tables.......................................................... 7-9
Default Table for Global Element PurchaseOrder .............................................................. 7-10
Data Dictionary Table for Registered Schemas ................................................................... 7-11

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Deleting an XML Schema with DBMS_XMLSCHEMA.DELETESCHEMA ................... 7-13
Registering a Local XML Schema .......................................................................................... 7-14
Registering a Global XML Schema ........................................................................................ 7-15
XML Schema Defining Documents with a Title To Be Translated ................................... 7-18
Untranslated Instance Document .......................................................................................... 7-19
XML Schema with Attribute xdb:translate for a Single-Valued Element........................ 7-20
Translated Document .............................................................................................................. 7-21
XML Schema with Attribute xdb:translate for a Multi-Valued Element......................... 7-22
Translated Document for an XML Schema with Multiple-Valued Elements ................. 7-24
Inserting a Document with No Language Information...................................................... 7-25
Document After Insertion into the Repository .................................................................... 7-25
Inserting a Document with Language Information ............................................................ 7-25
Document After Insertion....................................................................................................... 7-26
Creating XML Schema-Based XMLType Tables and Columns ........................................ 7-29
Specifying CLOB Storage for Schema-Based XMLType Tables and Columns............... 7-32
Specifying Structured Storage Options for XMLType Tables and Columns .................. 7-32
Using STORE ALL VARRAYS AS......................................................................................... 7-33
Using Common Schema Annotations................................................................................... 7-35
Registering an Annotated XML Schema .............................................................................. 7-37
Querying Metadata from a Registered XML Schema......................................................... 7-43
Mapping XML Schema Data Types to SQL Data Types using Attribute SQLType ...... 7-46
XPath Rewrite.............................................................................................................................. 8-2
Execution Plan Generated When XPath Rewrite Does Not Occur ...................................... 8-4
Analyzing an Execution Plan to Determine a Column to Index.......................................... 8-4
Creating an Index on a Column Targeted by a Predicate ..................................................... 8-5
Creating a Function-Based Index for a Column Targeted by a Predicate .......................... 8-5
Execution Plan Showing that Index Is Picked Up.................................................................. 8-5
Creating a Function-Based Index for a Column Targeted by a Predicate .......................... 8-6
Execution Plan for a Selection of Collection Elements .......................................................... 8-6
Creating an Index for Direct Access to an Ordered Collection Table ................................. 8-7
Generating an XML Schema with Function GENERATESCHEMA ................................... 9-2
Adding a Unique Constraint to the Parent Element of an Attribute................................... 9-3
Setting SQLInline to False for Out-Of-Line Storage .............................................................. 9-5
Generated XMLType Tables and Types .................................................................................. 9-5
Querying an Out-Of-Line Table................................................................................................ 9-6
XPath Rewrite for an Out-Of-Line Table................................................................................. 9-7
Using an Index with an Out-Of-Line Table ............................................................................ 9-7
Storing a Collection Out of Line ............................................................................................... 9-8
Generated Out-Of-Line Collection Type ................................................................................. 9-9
Renaming an Intermediate Table of REF Values.................................................................... 9-9
XPath Rewrite for an Out-Of-Line Collection......................................................................... 9-9
XPath Rewrite for an Out-Of-Line Collection, with Index on REFs................................. 9-10
Specifying Partitioning Information During XML Schema Registration......................... 9-11
Specifying Partitioning Information During Table Creation............................................. 9-12
Oracle XML DB XML Schema: Mapping complexType XML Fragments to LOBs........ 9-14
XML Schema Inheritance: complexContent as an Extension of complexTypes ............. 9-15
Inheritance in XML Schema: Restrictions in complexTypes ............................................. 9-16
XML Schema complexType: Mapping complexType to simpleContent ......................... 9-17
XML Schema: Mapping complexType to any/anyAttribute ............................................ 9-18
An XML Schema with Circular Dependency ...................................................................... 9-19
XML Schema: Cycling Between complexTypes .................................................................. 9-20
XML Schema: Cycling Between complexTypes, Self-Reference ....................................... 9-21
An XML Schema that Includes a Non-Existent XML Schema........................................... 9-23
Using the FORCE Option to Register XML Schema xm40.xsd ......................................... 9-23
Trying to Create a Table Using a Cyclic XML Schema....................................................... 9-24

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Using the FORCE Option to Register XML Schema xm40a.xsd .......................................
Recursive XML Schema...........................................................................................................
Out-of-line Table ......................................................................................................................
Invalid Default Table Sharing ................................................................................................
Revised Purchase-Order XML Schema.................................................................................
evolvePurchaseOrder.xsl: Style Sheet to Update Instance Documents .........................
Loading Revised XML Schema and XSL Style Sheet........................................................
Updating an XML Schema using DBMS_XMLSCHEMA.COPYEVOLVE....................
Splitting a Complex Type into Two Complex Types .......................................................
diffXML Parameter Document.............................................................................................
Registering an XML Schema and Inserting XML Data ......................................................
Retrieving a Style Sheet using XMLTRANSFORM and DBURITYPE .............................
Retrieving a Style Sheet using XMLTRANSFORM and a Subquery................................
Using Method TRANSFORM() with a Transient Style Sheet............................................
Validating XML using Method ISSCHEMAVALID() in SQL ...........................................
Validating XML using Method ISSCHEMAVALID() in PL/SQL ....................................
Validating XML using Method SCHEMAVALIDATE() within Triggers .......................
Checking XML Validity using XMLISVALID within CHECK Constraints ....................
Simple Query using Oracle SQL Function CONTAINS ....................................................
Restricting a Query using CONTAINS and WITHIN ........................................................
Restricting a Query using CONTAINS and INPATH........................................................
ora:contains with an Arbitrarily Complex Text Query ......................................................
CONTAINS Query with a Simple Boolean Operator.........................................................
CONTAINS Query with Complex Boolean .........................................................................
CONTAINS Query with Stemming ......................................................................................
CONTAINS Query with Complex Query Expression........................................................
Simple CONTAINS Query with SCORE ..............................................................................
WITHIN.....................................................................................................................................
Nested WITHIN .......................................................................................................................
WITHIN an Attribute ..............................................................................................................
WITHIN and AND: Two Words in Some Comment Section............................................
WITHIN and AND: Two Words in the Same Comment ...................................................
WITHIN and AND: No Parentheses.....................................................................................
WITHIN and AND: Parentheses Illustrating Operator Precedence ................................
Structure Inside Full-Text Predicate: INPATH....................................................................
Structure Inside Full-Text Predicate: INPATH....................................................................
INPATH with Complex Path Expression (1) .....................................................................
INPATH with Complex Path Expression (2) .....................................................................
Nested INPATH .....................................................................................................................
Nested INPATH Rewritten ..................................................................................................
Simple HASPATH .................................................................................................................
HASPATH Equality...............................................................................................................
HASPATH with Other Operators .......................................................................................
Scoping the Results of a CONTAINS Query .....................................................................
Projecting the Result of a CONTAINS Query using ora:contains ..................................
Simple CONTEXT Index on Table PURCHASE_ORDERS .............................................
Simple CONTEXT Index on XMLType Table with Path Section Group .......................
Simple CONTEXT Index on XMLType Column ...............................................................
Simple CONTEXT Index on XMLType Table....................................................................
CONTAINS Query on XMLType Table .............................................................................
CONTAINS: Default Case Matching ..................................................................................
Create a Preference for Mixed Case ....................................................................................
CONTEXT Index on PURCHASE_ORDERS Table, Mixed Case....................................
CONTAINS: Mixed (Exact) Case Matching.......................................................................
Simple CONTEXT Index on purchase_orders Table with Path Section Group ...........

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Using ora:contains with XMLQuery and XMLExists .......................................................
Create a Policy to Use with ora:contains ............................................................................
Finding a Stopword using ora:contains..............................................................................
Finding a Stopword using ora:contains and Policy my_nostopwords_policy .............
ora:contains, Default Case-Sensitivity ................................................................................
Create a Preference for Mixed Case ....................................................................................
Create a Policy with Mixed Case (Case-Insensitive) ........................................................
ora:contains, Case-Sensitive (1)............................................................................................
ora:contains, Case-Sensitive (2)............................................................................................
ora:contains in Large Table...................................................................................................
B-tree Index on ID ..................................................................................................................
ora:contains in Large Table, with Additional Predicate...................................................
ora:contains Search for "electric"..........................................................................................
Using XQuery Pragma ora:use_text_index with ora:contains ........................................
Purchase Order XML Document, po001.xml .....................................................................
Create Table PURCHASE_ORDERS ..................................................................................
Create Table PURCHASE_ORDERS_XMLTYPE .............................................................
Create Table PURCHASE_ORDERS_XMLTYPE_TABLE ...............................................
Purchase-Order XML Schema for Full-Text Search Examples........................................
Creating and Manipulating a DOM Document ................................................................
Creating an Element Node and Obtaining Information About It...................................
Creating a User-Defined Subtype of SYS.util_BinaryOutputStream() ..........................
Retrieving Node Value with a User-Defined Stream .......................................................
Get-Pull of Binary Data .........................................................................................................
Get-Pull of Character Data ...................................................................................................
Set-Pull of Binary Data ..........................................................................................................
Set-Push of Binary Data ........................................................................................................
Parsing an XML Document ..................................................................................................
Transforming an XML Document using an XSL Style Sheet...........................................
Inserting Data with Specified Columns................................................................................
Updating Data with Key Columns........................................................................................
DBMS_XMLSTORE.DELETEXML Example........................................................................
Querying an XMLType Table using JDBC ...........................................................................
Selecting XMLType Data using getStringVal() and getCLOB()........................................
Returning XMLType Data using getObject() .......................................................................
Returning XMLType Data using an Output Parameter.....................................................
Updating XMLType Data using SQL UPDATE with Constructor XMLType................
Updating XMLType Data using SQL UPDATE with setObject() .....................................
Retrieving Metadata about XMLType Data using JDBC ...................................................
Updating an Element in an XMLType Column using JDBC.............................................
Updated Purchase-Order Document ....................................................................................
Manipulating an XMLType Column using JDBC ...............................................................
Java Method insertXML() .....................................................................................................
Java Method getCLOB() ........................................................................................................
Creating a DOM Object with the Java DOM API..............................................................
Using the Java DOM API with Binary XML ......................................................................
Using OCIXMLDBINITXMLCTX() and OCIXMLDBFREEXMLCTX() ...........................
Using the C API for XML with Binary XML ........................................................................
Using the Oracle XML DB Pull Parser ................................................................................
Using the DOM to Count Ordered Parts............................................................................
Retrieve XMLType Data to .NET...........................................................................................
XMLELEMENT: Formatting a Date ......................................................................................
XMLELEMENT: Generating an Element for Each Employee ...........................................
XMLELEMENT: Generating Nested XML ..........................................................................
XMLELEMENT: Generating Employee Elements with Attributes ID and Name .........

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XMLELEMENT: Characters in Generated XML Are Not Escaped ..................................
Creating a Schema-Based XML Document using XMLELEMENT with Namespaces..
XMLELEMENT: Generating an Element from a User-Defined Data-Type Instance.....
XMLFOREST: Generating Elements with Attribute and Child Elements .......................
XMLFOREST: Generating an Element from a User-Defined Data-Type Instance .......
XMLCONCAT: Concatenating XMLType Instances from a Sequence..........................
XMLCONCAT: Concatenating XML Elements ................................................................
XMLAGG: Generating a Department Element with Child Employee Elements .........
XMLAGG: Using GROUP BY to Generate Multiple Department Elements.................
XMLAGG: Generating Nested Elements............................................................................
Using SQL/XML Function XMLPI......................................................................................
Using SQL/XML Function XMLCOMMENT....................................................................
Using SQL/XML Function XMLSERIALIZE.....................................................................
Using SQL/XML Function XMLPARSE.............................................................................
Using Oracle SQL Function XMLRoot................................................................................
XMLCOLATTVAL: Generating Elements with Attribute and Child Elements ...........
Using Oracle SQL Function XMLCDATA .........................................................................
DBMS_XMLGEN: Generating Simple XML ......................................................................
DBMS_XMLGEN: Generating Simple XML with Pagination (Fetch) ............................
DBMS_XMLGEN: Generating XML using Object Types.................................................
DBMS_XMLGEN: Generating XML using User-Defined Data-Type Instances...........
DBMS_XMLGEN: Generating an XML Purchase Order..................................................
DBMS_XMLGEN: Generating a New Context Handle from a REF Cursor..................
DBMS_XMLGEN: Specifying NULL Handling ................................................................
DBMS_XMLGEN: Generating Recursive XML with a Hierarchical Query ..................
DBMS_XMLGEN: Binding Query Variables using SETBINDVALUE() .......................
Creating XML Data using SYS_XMLGEN .........................................................................
SYS_XMLGEN: Generating an XML Element from a Database Column ......................
SYS_XMLGEN: Converting a Scalar Value to XML Element Contents .........................
SYS_XMLGEN: Default Element Name ROW ..................................................................
Overriding the Default Element Name using SYS_XMLGEN with XMLFormat ........
SYS_XMLGEN: Converting a User-Defined Data-Type Instance to XML ....................
SYS_XMLGEN: Converting an XMLType Instance..........................................................
Using SYS_XMLGEN with Object Views ...........................................................................
Using XMLAGG ORDER BY Clause...................................................................................
Returning a Rowset using XMLTABLE..............................................................................
Creating an XMLType View using XMLELEMENT ..........................................................
Creating an XMLType View using Object Types and SYS_XMLGEN ............................
Registering XML Schema emp_simple.xsd..........................................................................
Creating an XMLType View using SQL/XML Publishing Functions .............................
Querying an XMLType View .................................................................................................
Using Namespace Prefixes with SQL/XML Publishing Functions..................................
XML Schema with No Target Namespace ...........................................................................
Creating a View for an XML Schema with No Target Namespace ..................................
Using SQL/XML Functions in XML Schema-Based XMLType Views............................
Creating Object Types for Schema-Based XMLType Views............................................
Generating an XML Schema with DBMS_XMLSCHEMA.GENERATESCHEMA ......
Registering XML Schema emp_complex.xsd.....................................................................
Creating XMLType View emp_xml ....................................................................................
Creating an Object View and an XMLType View on the Object View ..........................
Creating Object Types ...........................................................................................................
Registering XML Schema dept_complex.xsd ....................................................................
Creating XMLType View dept_xml using Object Type dept_t.......................................
Creating XMLType View dept_xml using Relational Data Directly..............................
Creating an XMLType View by Restricting Rows from an XMLType Table................

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Creating an XMLType View by Transforming an XMLType Table...............................
Determining Whether an XMLType View is Implicitly Updatable ...............................
Using HTTPURIType PL/SQL Method GETCONTENTTYPE()......................................
Creating and Querying a URI Column.................................................................................
Using Different Kinds of URI, Created in Different Ways ................................................
Access a Repository Resource by URI using an XDBUri .................................................
Using PL/SQL Method GETXML() with XMLCAST and XMLQUERY ......................
Targeting a Complete Table using a DBUri .......................................................................
Targeting a Particular Row in a Table using a DBUri ......................................................
Targeting a Specific Column using a DBUri ......................................................................
Targeting an Object Column with Specific Attribute Values using a DBUri................
Retrieve Only the Text Value of a Node using a DBUri...................................................
Targeting a Collection using a DBUri .................................................................................
URIFACTORY: Registering the ECOM Protocol .............................................................
SYS_DBURIGEN: Generating a DBUri that Targets a Column ......................................
Passing Columns with Single Arguments to SYS_DBURIGEN......................................
Inserting Database References using SYS_DBURIGEN ...................................................
Creating the Travel Story Table ...........................................................................................
A Function that Returns the First 20 Characters ...............................................................
Creating a Travel View for Use with SYS_DBURIGEN ...................................................
Retrieving a URL using SYS_DBURIGEN in RETURNING Clause...............................
Changing the Installation Location of DBUriServlet ........................................................
Restricting Servlet Access to a Database Role ...................................................................
Registering a Handler for a DBUri Prefix ..........................................................................
Querying PATH_VIEW to Determine Link Type ...............................................................
Obtaining the OID Path of a Resource..................................................................................
Creating a Weak Link using an OID Path ............................................................................
Resource Configuration File...................................................................................................
applicationData Element.........................................................................................................
XInclude Used in a Book Document to Include Parts and Chapters ...............................
Expanding Document Inclusions using XDBURIType ......................................................
Querying Document Links Mapped From XLink Links ...................................................
Querying Document Links Mapped From XInclude Links ..............................................
Mapping XInclude Links to Hard Document Links, with OID Retrieval .....................
Mapping XLInk Links to Weak Links, with Named-Path Retrieval ..............................
Configuring XInclude Document Decomposition ............................................................
Repository Document, Showing Generated xi:include Elements...................................
Creating a Repository Resource.............................................................................................
Creating a Version-Controlled Resource..............................................................................
Retrieving Resource Content by Referencing the Resource ID.........................................
Checking Out a Version-Controlled Resource ....................................................................
Updating Resource Content ...................................................................................................
Checking In a Version-Controlled Resource........................................................................
Retrieving Resource Version Content using XDBURITYPE and CREATEOIDPATH ..
Retrieving Resource Version Content using GETCONTENTSCLOBBYRESID .............
Retrieving Resource Version Metadata using GETRESOURCEBYRESID ......................
Canceling a Check-Out using UNCHECKOUT .................................................................
Determining Paths Under a Path: Relative ..........................................................................
Determining Paths Under a Path: Absolute.........................................................................
Determining Paths Not Under a Path ...................................................................................
Determining Paths using Multiple Correlations ................................................................
Relative Path Names for Three Levels of Resources.........................................................
Extracting Resource Metadata using UNDER_PATH......................................................
Using Functions PATH and DEPTH with PATH_VIEW.................................................
Extracting Link and Resource Information from PATH_VIEW ....................................

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All Repository Paths to a Certain Depth Under a Path ...................................................
Locating a Repository Path using EQUALS_PATH .........................................................
Retrieve RESID of a Given Resource...................................................................................
Obtaining the Path Name of a Resource from its RESID .................................................
Folders Under a Given Path .................................................................................................
Joining RESOURCE_VIEW with an XMLType Table.......................................................
Deleting Resources.................................................................................................................
Deleting Links to Resources .................................................................................................
Deleting a Nonempty Folder................................................................................................
Updating a Resource .............................................................................................................
Updating a Path in the PATH_VIEW ................................................................................
Updating Resources Based on Attributes...........................................................................
Finding Resources Inside a Folder ......................................................................................
Copying Resources ................................................................................................................
Find All Resources Containing "Paper"..............................................................................
Find All Resources Containing "Paper" that are Under a Specified Path......................
Managing Resources using DBMS_XDB ..............................................................................
Using DBMS_XDB.GETACLDOCUMENT..........................................................................
Using DBMS_XDB.SETACL ...................................................................................................
Using DBMS_XDB.CHANGEPRIVILEGES .........................................................................
Using DBMS_XDB.GETPRIVILEGES ...................................................................................
Using DBMS_XDB.CFG_GET ................................................................................................
Using DBMS_XDB.CFG_UPDATE........................................................................................
Simple Access Control Entry (ACE) that Grants a Privilege .............................................
Simple Access Control List (ACL) that Grants a Privilege ................................................
Element extends-from .............................................................................................................
Element constrained-with.......................................................................................................
Complementing a Set of Principals with Element invert.................................................
ACE with Start and End Dates.............................................................................................
Creating an ACL using CREATERESOURCE ...................................................................
Retrieving an ACL Document, Given its Repository Path ..............................................
Setting the ACL of a Resource..............................................................................................
Deleting an ACL.....................................................................................................................
Updating (Replacing) an Access Control List....................................................................
Appending ACEs to an Access Control List ......................................................................
Deleting an ACE from an Access Control List...................................................................
Retrieving the ACL Document for a Resource ..................................................................
Retrieving Privileges Granted to the Current User for a Particular Resource..............
Checking If a User Has a Certain Privileges on a Resource ............................................
Checking User Privileges using ACLCheckPrivileges .....................................................
Retrieving the Path of the ACL that Protects a Given Resource .....................................
Retrieving the Paths of All Resources Protected by a Given ACL .................................
ACL Referencing an LDAP User .........................................................................................
ACL Referencing an LDAP Group ......................................................................................
Navigating Oracle ASM Folders..........................................................................................
Transferring Oracle ASM Files Between Databases with FTP proxy Method..............
FTP Connection Using IPv6 .................................................................................................
Modifying the Default Timeout Value of an FTP Session ...............................................
Register an XML Schema for Technical Photo Information ..............................................
Register an XML Schema for Photo Categorization ...........................................................
Add Metadata to a Resource – Technical Photo Information ...........................................
Add Metadata to a Resource – Photo Content Categories.................................................
Delete Specific Metadata from a Resource ...........................................................................
Adding Metadata to a Resource using DML with RESOURCE_VIEW ...........................
Adding Metadata using WebDAV PROPPATCH ..............................................................

25-12
25-12
25-12
25-13
25-13
25-13
25-14
25-14
25-15
25-16
25-17
25-18
25-18
25-19
25-20
25-20
26-2
26-4
26-4
26-5
26-6
26-7
26-8
27-4
27-4
27-9
27-9
27-10
27-11
27-11
27-12
27-12
27-12
27-13
27-14
27-14
27-14
27-15
27-15
27-16
27-17
27-17
27-21
27-21
28-11
28-12
28-13
28-14
29-3
29-4
29-5
29-6
29-6
29-7
29-8

29–8
29–9
30–1
30–2
30–3
30–4
30–5
31–1
31–2
31–3
31–4
31–5
31–6
31–7
31–8
31–9
31–10
32–1
32–2
33–1
33–2
33–3
33–4
33–5
33–6
33–7
33–8
33–9
34–1
34–2
35–1
35–2
35–3
36–1
36–2
36–3
36–4
36–5
36–6
37–1
37–2
37–3
37–4
A–1
A–2
A–3
A–4
A–5

Query XML Schema-Based Resource Metadata ................................................................
Add Non-Schema-Based Metadata to a Resource ............................................................
Resource Configuration File for Java Event Listeners with Preconditions .....................
Resource Configuration File for PL/SQL Event Listeners with No Preconditions .....
PL/SQL Code Implementing Event Listeners...................................................................
Java Code Implementing Event Listeners ..........................................................................
Invoking Event Handlers......................................................................................................
JCR Node Representation of MyFolder ...............................................................................
Code Fragment Showing How to Get a Repository Object ...............................................
Uploading a File using Oracle XML DB Content Connector ............................................
Uploading a File Using the Command Line ........................................................................
XML Document with XML Schema-Based Content .........................................................
XML Schema ...........................................................................................................................
JCR Representation of XML Content Not Registered for JCR Use .................................
JCR Representation of XML Content Registered for JCR Use.........................................
Registering an XML Schema for Use with Oracle XML DB ............................................
Registering an XML Schema for Use with JCR..................................................................
An Oracle XML DB Servlet.....................................................................................................
Registering and Mapping an Oracle XML DB Servlet........................................................
Adding a Web Services Configuration Servlet ....................................................................
Verifying Addition of Web Services Configuration Servlet ..............................................
XML Schema for Database Queries To Be Processed by Web Service.............................
Input XML Document for SQL Query using Query Web Service ....................................
Output XML Document for SQL Query using Query Web Service .................................
Definition of PL/SQL Function Used for Web-Service Access.........................................
WSDL Document Corresponding to a Stored PL/SQL Function.....................................
Input XML Document for PL/SQL Query using Web Service .........................................
Output XML Document for PL/SQL Query using Web Service ......................................
Oracle XML DB Configuration File .......................................................................................
Updating the Configuration File using CFG_UPDATE and CFG_GET ........................
Data File filelist.dat: List of XML Files to Load ...................................................................
Control File load_datra.ctl, for Loading Purchase-Order XML Documents ...................
Loading XML Data Using Shell Command sqlldr ..............................................................
Exporting XMLType Data in TABLE Mode.........................................................................
Importing XMLType Data in TABLE Mode ........................................................................
Creating Table po2...................................................................................................................
Exporting XMLType Data in SCHEMA Mode ....................................................................
Importing XMLType Data in SCHEMA Mode ...................................................................
Importing XMLType Data in SCHEMA Mode, Remapping Schema ..............................
Creating a Queue Table and Queue ......................................................................................
Creating a Transformation to Convert Message Data to XML..........................................
Applying a Transformation before Sending Messages Overseas .....................................
XMLType and AQ: Dequeuing Messages ............................................................................
Annotated Purchase-Order XML Schema, purchaseOrder.xsd ........................................
Revised Purchase-Order XML Schema.................................................................................
PurchaseOrder.xsl Style Sheet ...............................................................................................
Inserting XML Data into an XMLType Table using C........................................................
Using OCIXmlDbInitXmlCtx() and OCIXmlDbFreeXmlCtx() ..........................................

29-10
29-11
30-9
30-11
30-11
30-13
30-15
31-3
31-7
31-8
31-9
31-12
31-12
31-12
31-13
31-13
31-14
32-7
32-9
33-2
33-3
33-4
33-5
33-6
33-7
33-8
33-9
33-9
34-7
34-10
35-4
35-4
35-4
36-4
36-5
36-5
36-5
36-5
36-6
37-6
37-6
37-7
37-7
A-30
A-33
A-38
A-43
A-47

xxxvii

List of Figures
1–1
1–2
1–3
1–4
1–5
1–6
1–7
2–1
2–2
3–1
3–2
3–3
3–4
3–5
3–6
3–7
3–8
4–1
4–2
4–3
4–4
4–5
4–6
4–7
4–8
4–9
4–10
5–1
5–2
6–1
7–1
7–2
7–3
7–4
7–5
7–6
9–1
9–2
9–3
9–4
9–5
11–1
11–2
13–1
13–2
13–3
15–1
18–1
18–2
18–3
18–4
18–5
18–6
18–7
xxxviii

XMLType Storage and Oracle XML DB Repository .............................................................. 1-3
XMLType Storage ....................................................................................................................... 1-4
Oracle XML DB Repository Architecture ................................................................................ 1-9
Web Browser View of Oracle XML DB Repository ............................................................ 1-10
XML Use Cases and XMLType Storage Models.................................................................. 1-17
Oracle XML DB Benefits ......................................................................................................... 1-23
Unifying Data and Content: Some Common XML Architectures .................................... 1-24
Oracle XML DB Storage Options for XML Data..................................................................... 2-6
Oracle XML DB Application Program Interface (API) Stack ............................................ 2-10
Loading Content into the Repository using Windows Explorer ...................................... 3-10
XMLSpy Graphical Representation of the PurchaseOrder XML Schema ....................... 3-17
XMLSpy Showing Support for Oracle XML DB Schema Annotations ............................ 3-24
Copying Files into Oracle XML DB Repository................................................................... 3-70
Path-Based Access using HTTP and a URL ......................................................................... 3-72
Updating and Editing Content Stored in Oracle XML DB using Microsoft Word ........ 3-78
Database XSL Transformation of a PurchaseOrder using DBUri Servlet........................ 3-89
Database XSL Transformation of Departments Table using DBUri Servlet.................... 3-90
XMLExists Syntax ....................................................................................................................... 4-3
XMLCast Syntax.......................................................................................................................... 4-4
UPDATEXML Syntax .............................................................................................................. 4-15
INSERTCHILDXML Syntax ................................................................................................... 4-24
INSERTCHILDXMLBEFORE Syntax.................................................................................... 4-26
INSERTCHILDXMLAFTER Syntax ...................................................................................... 4-27
INSERTXMLBEFORE Syntax................................................................................................. 4-28
INSERTXMLAFTER Syntax ................................................................................................... 4-30
APPENDCHILDXML Syntax................................................................................................. 4-31
DELETEXML Syntax ............................................................................................................... 4-32
XMLQUERY Syntax.................................................................................................................... 5-6
XMLTABLE Syntax..................................................................................................................... 5-7
XML Use Cases and XML Indexing ...................................................................................... 6-10
Creating an XMLType Table – CREATE TABLE ................................................................ 7-28
Creating an XMLType Table – XMLType_table.................................................................. 7-28
Creating an XMLType Table – table_properties ................................................................. 7-28
Creating an XMLType Table – XMLType_virtual_columns ............................................. 7-29
How Oracle XML DB Maps XML Schema-Based XMLType Tables ................................ 7-45
Mapping simpleType: XML Strings to SQL VARCHAR2 or CLOB................................. 7-49
Mapping complexType to SQL for Out-Of-Line Storage...................................................... 9-4
Mapping complexType XML Fragments to Character Large Objects (CLOB) .............. 9-15
Cross Referencing Between Different complexTypes in the Same XML Schema .......... 9-20
Self-Referencing Complex Type within an XML Schema .................................................. 9-22
Cyclical References Between XML Schemas ........................................................................ 9-22
XMLTRANSFORM Syntax ..................................................................................................... 11-2
Using XMLTRANSFORM....................................................................................................... 11-2
Using the PL/SQL DOM API for XMLType...................................................................... 13-10
Using the PL/SQL Parser API for XMLType .................................................................... 13-20
Using the PL/SQL XSLT Processor for XMLType............................................................ 13-22
Using the Java DOM API for XMLType ............................................................................. 15-16
XMLELEMENT Syntax ........................................................................................................... 18-3
XMLAttributes Clause Syntax (XMLATTRIBUTES) .......................................................... 18-4
XMLFOREST Syntax................................................................................................................ 18-9
XMLCONCAT Syntax........................................................................................................... 18-11
XMLAGG Syntax ................................................................................................................... 18-12
XMLPI Syntax......................................................................................................................... 18-15
XMLComment Syntax ........................................................................................................... 18-16

18–8
18–9
18–10
18–11
18–12
18–13
18–14
18–15
19–1
20–1
20–2
21–1
21–2
21–3
21–4
25–1
25–2
25–3
25–4
25–5
25–6
28–1
28–2
37–1
37–2

XMLSerialize Syntax.............................................................................................................. 18-16
XMLParse Syntax ................................................................................................................... 18-18
XMLRoot Syntax .................................................................................................................... 18-19
XMLCOLATTVAL Syntax.................................................................................................... 18-19
XMLCDATA Syntax .............................................................................................................. 18-21
Using PL/SQL Package DBMS_XMLGEN ........................................................................ 18-22
SYS_XMLGEN Syntax........................................................................................................... 18-46
SYS_XMLAGG Syntax .......................................................................................................... 18-54
Creating XMLType Views Clause: Syntax ........................................................................... 19-2
A DBUri Corresponds to an XML Visualization of Relational Data .............................. 20-13
SYS_DBURIGEN Syntax ....................................................................................................... 20-22
A Folder Tree, Showing Hierarchical Structures in the Repository ................................. 21-2
Oracle XML DB Folders in Windows Explorer ................................................................. 21-10
Accessing Repository Data using HTTP(S)/WebDAV and Navigational Access From IE
Browser: Viewing Web Folders 21-10
Oracle ASM Virtual Folder Hierarchy ................................................................................ 21-13
Accessing Repository Resources using RESOURCE_VIEW and PATH_VIEW ............. 25-2
RESOURCE_VIEW and PATH_VIEW Structure ................................................................ 25-4
RESOURCE_VIEW and PATH_VIEW Explained............................................................... 25-5
UNDER_PATH Syntax ........................................................................................................... 25-6
EQUALS_PATH Syntax.......................................................................................................... 25-7
PATH Syntax ............................................................................................................................ 25-8
Oracle XML DB Architecture: Protocol Server ................................................................... 28-2
Creating a WebFolder in Microsoft Windows................................................................... 28-22
Oracle Streams Advanced Queuing and XML Message Payloads................................... 37-3
iDAP Architecture for Performing AQ Operations using HTTP(S) ................................. 37-5

xxxix

xl

List of Tables
1–1
1–2
1–3
3–1
4–1
5–1
5–2
6–1
6–2
6–3
6–4
6–5
6–6
6–7
6–8
7–1
7–2
7–3
7–4
7–5
7–6
7–7
7–8
7–9
7–10
8–1
10–1
10–2
10–3
10–4
10–5
10–6
13–1
15–1
16–1
16–2
18–1
18–2
20–1
20–2
20–3
21–1
21–2
21–3
24–1
24–2
25–1
25–2
25–3
26–1
26–2
26–3
27–1

APIs Related to XML ................................................................................................................. 1-5
Catalog Views Related to XML ................................................................................................ 1-6
XMLType Storage Models: Relative Advantages .............................................................. 1-18
SQL*Loader – Conventional and Direct-Path Load Modes................................................. 3-9
Common XPath Constructs ...................................................................................................... 4-2
Predefined Namespaces and Prefixes.................................................................................. 5-10
oradb Expressions: Column Types for Comparisons ........................................................ 5-11
Basic XML Indexing Tasks........................................................................................................ 6-2
Tasks Involving XMLIndex Indexes with a Structured Component ................................. 6-2
Tasks Involving XMLIndex Indexes with an Unstructured Component .......................... 6-2
Miscellaneous Tasks Involving XMLIndex Indexes ............................................................. 6-3
XML and SQL Data Type Correspondence for XMLIndex............................................... 6-12
XMLIndex Path Table............................................................................................................. 6-14
Index Synchronization ........................................................................................................... 6-36
XMLIndex Static Public Views.............................................................................................. 6-37
XMLType Methods Related to XML Schema ..................................................................... 7-14
CREATE TABLE Encoding Options for Binary XML........................................................ 7-31
Annotations in Elements........................................................................................................ 7-39
Annotations in Elements Declaring Global complexType Elements .............................. 7-41
Annotations in XML Schema Declarations ......................................................................... 7-41
Mapping XML Schema String Data Types to SQL............................................................. 7-49
Mapping XML Schema Binary Data Types (hexBinary/base64Binary) to SQL ............ 7-49
Default Mapping of Numeric XML Schema Primitive Types to SQL............................. 7-49
Mapping XML Schema Date and Time Data Types to SQL ............................................. 7-50
Default Mapping of Other XML Schema Primitive and Derived Data Types to SQL.. 7-50
Sample of XPath Expressions that Are Rewritten to Underlying SQL Constructs .......... 8-2
Parameters of Procedure DBMS_XMLSCHEMA.COPYEVOLVE................................... 10-6
Errors Associated with Procedure DBMS_XMLSCHEMA.COPYEVOLVE................... 10-6
XML Schema Evolution: XMLType Table Temporary Table Columns ........................ 10-14
XML Schema Evolution: XMLType Column Temporary Table Columns ................... 10-14
Procedure copyEvolve Mapping Table ............................................................................. 10-14
Parameters of Procedure DBMS_XMLSCHEMA.INPLACEEVOLVE.......................... 10-19
XML and HTML DOM Node Types and Their Child Node Types ................................ 13-8
Java DOM API for XMLType: Classes.............................................................................. 15-14
OCIXmlDbInitXMlCtx() Parameters.................................................................................... 16-3
Common XMLType Operations in C ................................................................................. 16-15
DBMS_XMLGEN Functions and Procedures .................................................................. 18-24
Attributes of the XMLFormat Object ................................................................................. 18-48
URIType PL/SQL Methods................................................................................................... 20-4
URIFACTORY PL/SQL Methods....................................................................................... 20-20
DBUriServlet: Optional Arguments ................................................................................... 20-27
Synonyms for Oracle XML DB Repository Terms ............................................................. 21-4
Differences Between PATH_VIEW and RESOURCE_VIEW ......................................... 21-14
Accessing Oracle XML DB Repository: API Options ...................................................... 21-15
Oracle XML DB Versioning Terms....................................................................................... 24-2
PL/SQL Functions and Procedures in Package DBMS_XDB_VERSION..................... 24-10
Structure of RESOURCE_VIEW ........................................................................................... 25-3
Structure of PATH_VIEW...................................................................................................... 25-3
UNDER_PATH SQL Function Signature ........................................................................... 25-6
DBMS_XDB Resource Management Functions and Procedures ..................................... 26-2
DBMS_XDB: Security Management Procedures and Functions ...................................... 26-3
DBMS_XDB: Configuration Management Functions and Procedures ........................... 26-7
Database Privileges Needed for Operations on Oracle XML DB Resources.................. 27-4

xli

27–2
27–3
28–1
28–2
28–3
30–1
30–2
31–1
31–2
32–1
32–2
33–1
34–1
36–1

xlii

Atomic Privileges .................................................................................................................... 27-5
Aggregate Privileges .............................................................................................................. 27-6
Common Protocol Configuration Parameters .................................................................... 28-3
Configuration Parameters Specific to FTP .......................................................................... 28-4
Configuration Parameters Specific to HTTP(S)/WebDAV (Except Servlet Parameters)........
28-5
Predefined Repository Events............................................................................................... 30-3
Oracle XML DB Repository Operations and Events.......................................................... 30-5
Oracle XML DB Resource to JCR Mappings ....................................................................... 31-5
XML Schema Built-In Types Mapped to JCR Property Value Types........................... 31-14
XML Elements Defined for Servlet Deployment Descriptors .......................................... 32-3
Java Servlet 2.2 Methods that Are Not Implemented........................................................ 32-7
Web Service Mapping Between XML and SQL Data Types............................................. 33-7
DBMS_XDB_ADMIN Management Procedures .............................................................. 34-13
Format of the XMLType columns in the table with the corresponding format of the dump
file 36-2

Preface
This manual describes Oracle XML DB, and how you can use it to store, generate,
manipulate, manage, and query XML data in the database.
After introducing you to the heart of Oracle XML DB, namely the XMLType
framework and Oracle XML DB Repository, the manual provides a brief introduction
to design criteria to consider when planning your Oracle XML DB application. It
provides examples of how and where you can use Oracle XML DB.
The manual then describes ways you can store and retrieve XML data using Oracle
XML DB, APIs for manipulating XMLType data, and ways you can view, generate,
transform, and search on existing XML data. The remainder of the manual discusses
how to use Oracle XML DB Repository, including versioning and security, how to
access and manipulate repository resources using protocols, SQL, PL/SQL, or Java,
and how to manage your Oracle XML DB application using Oracle Enterprise
Manager. It also introduces you to XML messaging and Oracle Streams Advanced
Queuing XMLType support.
This Preface contains these topics:
■

Audience

■

Documentation Accessibility

■

Related Documents

■

Conventions

Audience
Oracle XML DB Developer's Guide is intended for developers building XML Oracle
Database applications.
An understanding of XML, XML Schema, XQuery, XPath, and XSL is helpful when
using this manual.
Many examples provided here are in SQL, PL/SQL, Java, or C. A working knowledge
of one of these languages is presumed.

Documentation Accessibility
For information about Oracle's commitment to accessibility, visit the Oracle
Accessibility Program website at
http://www.oracle.com/pls/topic/lookup?ctx=acc&id=docacc.

xliii

Access to Oracle Support
Oracle customers have access to electronic support through My Oracle Support. For
information, visit
http://www.oracle.com/pls/topic/lookup?ctx=acc&id=info or visit
http://www.oracle.com/pls/topic/lookup?ctx=acc&id=trs if you are
hearing impaired.

Related Documents
For more information, see these Oracle resources:
■

Oracle Database New Features Guide for information about the differences between
Oracle Database 11g and the Oracle Database 11g Enterprise Edition and the
available features and options. This book also describes features new to Oracle
Database 11g Release 2 (11.2).

■

Oracle Database XML Java API Reference

■

Oracle XML Developer's Kit Programmer's Guide

■

Oracle Database Error Messages. Oracle Database error message documentation is
available only as HTML. If you have access to only printed or PDF Oracle
Database documentation, you can browse the error messages by range. Once you
find the specific range, use the search (find) function of your Web browser to
locate the specific message. When connected to the Internet, you can search for a
specific error message using the error message search feature of the Oracle
Database online documentation.

■

Oracle Text Application Developer's Guide

■

Oracle Text Reference

■

Oracle Database Concepts.

■

Oracle Database Java Developer's Guide

■

Oracle Database Advanced Application Developer's Guide

■

Oracle Streams Advanced Queuing User's Guide

■

Oracle Database PL/SQL Packages and Types Reference

Many of the examples in this book use the sample schemas, which are installed by
default when you select the Basic Installation option with an Oracle Database
installation. Refer to Oracle Database Sample Schemas for information about how these
schemas were created and how you can use them yourself.
To download free release notes, installation documentation, white papers, or other
collateral, please visit the Oracle Technology Network (OTN). You must register online
before using OTN; registration is free and can be done at
http://www.oracle.com/technetwork/community/join/overview/index.html

If you already have a username and password for OTN, then you can go directly to the
documentation section of the OTN Web site at
http://www.oracle.com/technetwork/indexes/documentation/

For additional information, see:

xliv

■

http://www.w3.org/TR/xml/ – XML (language)

■

http://www.xml.com/pub/a/98/10/guide0.html – XML introduction

■

http://www.w3.org/XML/Schema – XML Schema

■

http://www.w3.org/2001/XMLSchema – XML Schema

■

http://www.w3.org/TR/xmlschema-0/ – XML Schema: primer

■

http://www.w3.org/TR/xmlschema-1/ – XML Schema: structures

■

http://www.w3.org/TR/xmlschema-2/ – XML Schema: data types

■

http://www.oasis-open.org/cover/schemas.html – XML Schema

■

http://www.xml.com/pub/a/2000/11/29/schemas/part1.html – XML
Schema

■

http://xml.coverpages.org/xmlMediaMIME.html – media/MIME types

■

http://www.w3.org/TR/xptr/ – XPointer

■

http://www.w3.org/TR/xpath – XPath 1.0

■

http://www.w3.org/TR/xpath20/ – XPath 2.0

■

■

■

http://www.zvon.org/xxl/XPathTutorial/General/examples.html –
XPath
XML In a Nutshell, by Elliotte Rusty Harold and W. Scott Means, O'Reilly, January
2001, http://www.oreilly.com/catalog/xmlnut/chapter/ch09.html
http://www.w3.org/TR/2002/NOTE-unicode-xml-20020218/ – Unicode
in XML

■

http://www.w3.org/TR/xml-names/ – XML namespaces

■

http://www.w3.org/TR/xml-infoset/ – information sets

■

http://www.w3.org/DOM/ – Document Object Model (DOM)

■

http://www.w3.org/TR/xslt – XSLT

■

http://www.w3.org/TR/xsl – XSL

■

http://www.oasis-open.org/cover/xsl.html – XSL

■

http://www.zvon.org/xxl/XSLTutorial/Output/index.html – XSL

■

http://www.w3.org/2002/ws/Activity.html – Web services

■

■

■

http://www.ietf.org/rfc/rfc959.txt – RFC 959: FTP Protocol
Specification
ISO/IEC 13249-2:2000, Information technology - Database languages - SQL
Multimedia and Application Packages - Part 2: Full-Text, International
Organization For Standardization, 2000
http://java.sun.com/xml/tutorial_intro.html – XML and Java
Note: Throughout this manual, "XML Schema" refers to the XML
Schema 1.0 recommendation, http://www.w3.org/XML/Schema.

Conventions
The following text conventions are used in this document:

xlv

Convention

Meaning

boldface

Boldface type indicates graphical user interface elements associated
with an action, or terms defined in text or the glossary.

italic

Italic type indicates book titles, emphasis, or placeholder variables for
which you supply particular values.

monospace

Monospace type indicates commands within a paragraph, URLs, code
in examples, text that appears on the screen, or text that you enter.

Code Examples
The code examples in this book are for illustration only. In many cases, however, you
can copy and paste parts of examples and run them in your environment.

Standard Database Schemas
Many of the examples in this book use the standard database schemas that are
included in your database. In particular, database schema OE contains XML
purchase-order documents in XMLType table purchaseorder, and XML documents
with warehouse information in XMLType column warehouse_spec of table
warehouses.
The purchase-order documents are also contained in Oracle XML DB Repository,
under the repository path /home/OE/PurchaseOrders/2002/. The XML schema
that governs these documents is file purchaseorder.xsd, at repository location
/home/OE/purchaseorder.xsd. An XSL style sheet that is used in some examples
to transform purchase-order documents is file purchaseorder.xsl, at repository
location /home/OE/purchaseorder.xsl. This XML schema and style sheet can also
be found in Appendix A, "Oracle-Supplied XML Schemas and Examples".
See Also:
■

■

Oracle Database Sample Schemas for information about database
schema HR
Oracle Database Sample Schemas for information about database
schema OE

Pretty Printing of XML Data
To promote readability, especially of lengthy or complex XML data, output is
sometimes shown pretty-printed (formatted) in code examples.

Execution Plans
Some of the code examples in this book present execution plans. These are for
illustration only. Running examples that are presented here in your environment is
likely to result in different execution plans from those presented here.

Reminder About Case Sensitivity
When examining the examples in this book, keep in mind the following:
■

■

xlvi

SQL is case-insensitive, but names in SQL code are implicitly uppercase, unless
you enclose them in double-quotes.
XML is case-sensitive. You must refer to SQL names in XML code using the correct
case: uppercase SQL names must be written as uppercase.

For example, if you create a table named my_table in SQL without using
double-quotes, then you must refer to it in XML code as "MY_TABLE".

Syntax Descriptions
Syntax descriptions are provided in this book for various SQL, PL/SQL, or other
command-line constructs in graphic form or Backus Naur Form (BNF). See Oracle
Database SQL Language Reference for information about how to interpret these
descriptions.

xlvii

xlviii

What's New in Oracle XML DB?
This chapter describes the new features and functionality, enhancements, APIs, and
product integration support added to Oracle XML DB for Oracle Database 11g.
It also describes the deprecation of certain Oracle XML DB constructs.

Oracle Database 11g Release 2 (11.2.0.3) Deprecated Oracle XML DB
Constructs
The following Oracle XML DB constructs are deprecated in Oracle Database 11g Release
2 (11.2.0.3). They are still supported in 11.2.0.3 for backward compatibility, but Oracle
recommends that you do not use them in new applications.
■

PL/SQL procedure DBMS_XDB_ADMIN.createRepositoryXMLIndex

■

PL/SQL procedure DBMS_XDB_ADMIN.XMLIndexAddPath

■

PL/SQL procedure DBMS_XDB_ADMIN.XMLIndexRemovePath

■

PL/SQL procedure DBMS_XDB_ADMIN.dropRepositoryXMLIndex

■

XML schema annotation (attribute) csx:encodingType

■

XMLIndex index on CLOB portions of hybrid XMLType storage, that is, on CLOB
data that is embedded within object-relational storage

Oracle Database 11g Release 2 (11.2.0.3) Other Changes in Oracle
XML DB
The following PL/SQL procedures have been moved from package DBMS_XDB to
package DBMS_XDB_ADMIN in Oracle Database 11g Release 2 (11.2.0.3):
■

moveXDB_tablespace

■

rebuildHierarchicalIndex

Oracle Database 11g Release 2 (11.2.0.2) New Features in Oracle
XML DB
The following Oracle XML DB features are new in Oracle Database 11g Release 2
(11.2.0.2).

xlix

Default Storage Model for XMLType
The default XMLType storage model is used if you do not specify a storage model
when you create an XMLType table or column. Prior to Oracle Database 11g Release 2
(11.2.0.2), unstructured (CLOB) storage was used by default. The default storage model
is now binary XML storage.
You can create a new table that uses binary XML storage and
populate it with existing XMLType data that is stored using CLOB
storage. Use CREATE TABLE AS SELECT..., selecting from the
existing data.
Note:

This functionality is available starting with Oracle Database 11g Release 2 (11.2.0.2).
Default LOB Storage for Binary XML
XMLType data that uses the binary XML storage model is stored internally using large
objects (LOBs). Prior to Oracle Database 11g Release 2 (11.2.0.2), binary XML data was
stored by default using the BasicFile LOB storage option. By default, LOB storage for
binary XML data now uses the SecureFile LOB storage option whenever possible.
If SecureFile LOB storage is not possible then the default behavior uses BasicFile LOB
storage. This can occur if either of the following is true:
■

■

The tablespace for the XMLType table does not use automatic segment space
management.
A setting in file init.ora prevents SecureFile LOB storage. For example, see
parameter DB_SECUREFILE.
See Also:
■

■

■

Oracle Database Administrator's Guide for information about
automatic segment space management
Oracle Database Reference for information about parameter DB_
SECUREFILE
"Oracle Database 11g Release 2 (11.2.0.2) Deprecated Oracle
XML DB Constructs" on page -li

This functionality is available starting with Oracle Database 11g Release 2 (11.2.0.2).
XQuery Pragma ora:defaultTable for Repository Query Performance
Previously, to obtain optimal performance for XQuery expressions that use fn:doc
and fn:collection over Oracle XML DB Repository resources, you needed to carry
out explicit joins with RESOURCE_VIEW. The new XQuery extension-expression
pragma ora:defaultTable now performs the necessary joins automatically.
This functionality is available starting with Oracle Database 11g Release 2 (11.2.0.2).
XML Diagnosability Mode: SQL*Plus System Variable XMLOptimizationCheck
You can use the SQL*Plus SET command with the new system variable
XMLOptimizationCheck to turn on an XML diagnosability mode for SQL. When
this mode is on, execution plans are automatically checked for XPath rewrite, and if a
plan is suboptimal then an error is raised and diagnostic information is written to the
trace file indicating which operators are not rewritten.
This functionality is available starting with Oracle Database 11g Release 2 (11.2.0.2).
l

See Also: "Diagnosing XQuery Optimization:
XMLOptimizationCheck" on page 5-35

Oracle Database 11g Release 2 (11.2.0.2) Deprecated Oracle XML DB
Constructs
The following Oracle XML DB constructs are deprecated in Oracle Database 11g Release
2 (11.2.0.2). They are still supported in 11.2.0.2 for backward compatibility, but Oracle
recommends that you do not use them in new applications.
■

■

XMLType data stored as binary XML using BasicFile LOB storage. See also the new
feature "Default LOB Storage for Binary XML" on page -l.
Oracle XQuery function ora:view – Use XQuery functions fn:doc and
fn:collection instead. See Chapter 5, "Using XQuery with Oracle XML DB".

Oracle Database 11g Release 2 (11.2.0.1) New Features in Oracle
XML DB
The following Oracle XML DB features are new in Oracle Database 11g Release 2
(11.2.0.1).
Partitioning XMLType Tables and Columns
For XMLType data stored object-relationally, when you partition a base XMLType table
or a base table with an XMLType column, any collection tables that use heap-based
table storage are now, by default, automatically equipartitioned also. Equipartitioning
means that there is a corresponding collection-table partition for each partition of the
base table. A child element is stored in the collection-table partition that corresponds
to the base-table partition of its parent element.
See Also: "Partitioning XMLType Tables and Columns Stored
Object-Relationally" on page 9-10

Access Control Enhancements
Access control lists (ACLs) have been enhanced in various ways, to provide
fine-grained access control that you can customize. You can define your own
privileges and associate them with users and roles in flexible ways. Inheritance is
available for ACLs. Access control entries (ACEs) can stipulate start and end dates.
You can control access for application users and roles that are not necessarily the same
as database users and roles.
See Also:

Chapter 27, "Repository Access Control"

Repository Read and Write Performance Enhancements
Performance has been improved for Oracle XML DB Repository read and write
operations.
Binary XML Performance Enhancements and Partitioning
The performance of queries and DML operations on binary XML tables has been
improved, and you can now partition binary XML tables, using a virtual column as the
partitioning key.

li

XMLIndex Enhancements
You can use XMLIndex to index islands of structured XML content embedded in
content that is generally unstructured. An XMLIndex index can thus index both
structured and unstructured XML content.
You can create a local XMLIndex index on data in partitioned XMLType tables.
See Also:

"XMLIndex" on page 6-7

Cost-Based XPath Rewrite
You can use a new optimizer hint to request cost-based optimization of XQuery
expressions.

Oracle Database 11g Release 2 (11.2.0.1) Deprecated Oracle XML DB
Constructs
The following Oracle XML DB constructs are deprecated in Oracle Database 11g Release
2 (11.2.0.1). They are still supported in 11.2.0.1 for backward compatibility, but Oracle
recommends that you do not use them in new applications.
■

■

■

■

■

■

■

■

■

■

lii

Oracle SQL function extract – Use SQL/XML function XMLQuery instead. See
"XMLQUERY SQL/XML Function in Oracle XML DB" on page 5-6.
Oracle SQL function extractValue – Use SQL/XML function XMLTable or
SQL/XML functions XMLCast and XMLQuery instead.
–

See "SQL/XML Functions XMLQUERY and XMLTABLE" on page 5-5 for
information about using function XMLTable

–

See "XMLCAST SQL/XML Function" on page 4-4 for information about using
functions XMLCast and XMLQuery

Oracle SQL function existsNode – Use SQL/XML function XMLExists instead.
See "XMLEXISTS SQL/XML Function" on page 4-3.
Oracle SQL function XMLSequence – Use SQL/XML function XMLTable instead.
See "XMLTABLE SQL/XML Function in Oracle XML DB" on page 5-7.
Oracle XPath function ora:instanceof – Use XQuery operator instance of
instead.
Oracle XPath function ora:instanceof-only – Use XML Schema attribute
xsi:type instead.
PL/SQL XMLType methods getStringVal(), getCLOBVal(), and
getBLOBVal(), – Use SQL/XML function XMLSerialize instead. See
"XMLSERIALIZE SQL/XML Function" on page 18-16.
PL/SQL XMLType method getNamespace() – Use XQuery function
fn:namespace-uri instead.
PL/SQL XMLType method getRootElement() – Use XQuery function
fn:local-name instead.
Function-based indexes on XMLType – Use XMLIndex with a structured
component instead. See "Function-Based Indexes" on page 6-5.

Oracle Database 11g Release 1 (11.1) New Features in Oracle XML DB
Binary XML
Binary XML is a new storage model for abstract data type XMLType, joining the
existing storage models of structured (object-relational) and unstructured (CLOB)
storage. Binary XML is XML-Schema aware, but it can also be used with XML data
that is not based on an XML schema. See "XMLType Storage Models" on page 1-14.
See Also:
■

■

■

■

Oracle Database Advanced Application Developer's Guide for an
overview of XMLType data stored as binary XML
Oracle Database SQL Language Reference for information about
creating XMLType tables and columns stored as binary XML
Oracle Database XML Java API Reference for information about
manipulating binary XML data using Java
Oracle Database XML C API Reference for information about
manipulating binary XML data using C

XMLIndex
A new index type is provided for XMLType: XMLIndex. This can greatly improve the
performance of XPath-based predicates and fragment extraction for XMLType data,
whether based on an XML schema or not. The new index type is a (logical) domain
index that consists of underlying physical tables and secondary indexes. See
Chapter 6, "Indexing XMLType Data".
Note: The CTXSYS.CTXXPath index is deprecated in Oracle Database
11g Release 1 (11.1). The functionality that was provided by
CTXXPath is now provided by XMLIndex.

Oracle recommends that you replace CTXXPath indexes with
XMLIndex indexes. The intention is that CTXXPath will no longer be
supported in a future release of the database.

See Also:
■

■

Oracle Database Reference for information about new view XIDX_
USER_PENDING
Oracle Database PL/SQL Packages and Types Reference for
information about new PL/SQL package DBMS_XMLINDEX

XMLType OCTs Now Use Heap Storage Instead of IOTs
You can store collections of XML elements as ordered collection tables (OCTs). OCTs
now use heap storage, by default. In prior releases, OCTs were index-organized tables
(IOTs), by default. A new XML schema registration option, REGISTER_NT_AS_IOT,
forces the use of IOTs.
See Also: "Controlling How Collections Are Stored for
Object-Relational XMLType Storage" on page 3-19

liii

Default Value of XML Schema Annotation storeVarrayAsTable Is Now true
In prior releases, the default value of XML schema annotation storeVarrayAsTable
was false; the default value is now true. This means that by default an XML
collection is stored as a set of rows in an ordered collection table (OCT). Each row
corresponds to an element in the collection. With annotation storeVarrayAsTable
= "false", the entire collection is instead serialized as a varray and stored in a LOB
column.
Using storeVarrayAsTable = "true" facilitates the efficient use of collections:
queries, updates, and creation of B-tree indexes.
See Also: "Controlling How Collections Are Stored for
Object-Relational XMLType Storage" on page 3-19 for more
information about storing XML collections object-relationally

Repository Events
Applications can now register listeners with handlers for events associated with
Oracle XML DB Repository operations such as creating, deleting, and updating a
resource. See Chapter 30, "Oracle XML DB Repository Events".
See Also:
■
■

■

■

Oracle Database XML Java API Reference for new Java methods
Oracle Database PL/SQL Packages and Types Reference for
information about new PL/SQL package DBMS_XEVENT
Oracle Database PL/SQL Packages and Types Reference for
information about new PL/SQL package DBMS_RESCONFIG
Oracle Database PL/SQL Packages and Types Reference for
information about new PL/SQL package DBMS_XDBRESOURCE

Support for Content Repository API for Java (JCR: JSR-170)
Oracle XML DB now supports Content Repository API for Java (JCR) and the JSR-170
standard. You can access Oracle XML DB Repository using the JCR APIs. See
Chapter 31, "Using Oracle XML DB Content Connector".
See Also: Oracle Database XML Java API Reference for new Java
methods

New Repository Resource Link Types
You can now create weak folder links to represent Oracle XML DB Repository
folder-child relationships. Hard links are still available, as well. See "Link Types" on
page 21-7.
See Also:
■

■

Oracle Database PL/SQL Packages and Types Reference for updates to
PL/SQL package DBMS_XDB
Oracle Database SQL Language Reference for updates to function
under_path

Support for WebDAV Privileges and New Oracle XML DB Privileges
All WebDAV privileges are now supported by Oracle XML DB Repository. In addition,
there are some new Oracle XML DB-specific atomic privileges. See Chapter 27,
"Repository Access Control".
liv

See Also:
■

■

■

Oracle Database PL/SQL Packages and Types Reference for
information about new PL/SQL package DBMS_NETWORK_ACL_
ADMIN
Oracle Database PL/SQL Packages and Types Reference for
information about PL/SQL package UTL_TCP
Oracle Database PL/SQL Packages and Types Reference for
information about PL/SQL package UTL_INADDR

Web Services
You can now access Oracle Database through Web services. You can write and deploy
Web services that can query the database using SQL or XQuery, or access stored
PL/SQL functions and procedures. See Chapter 33, "Using Native Oracle XML DB
Web Services"
In-Place XML Schema Evolution
In many cases, you can now evolve XML schemas without copying the corresponding
XML instance documents. See Chapter 10, "XML Schema Evolution".
See Also: Oracle Database PL/SQL Packages and Types Reference for
updates to PL/SQL package DBMS_XMLSCHEMA

Support for Recursive XML Schemas
Oracle XML DB now performs XPath rewrite on some queries that use '//' in XPath
expressions to target nodes at multiple or arbitrary depths, even when the XML data
conforms to a recursive XML schema. See "Support for Recursive Schemas" on
page 9-24
See Also: Oracle Database PL/SQL Packages and Types Reference for
updates to PL/SQL package DBMS_XMLSCHEMA

Support for XLink and XInclude
Oracle XML DB now supports the XLink and XInclude standards. See Chapter 23,
"Using XLink and XInclude with Oracle XML DB".
Support for XML Translations
You can now associate natural-language translation information with XML schemas
and corresponding instance documents. This includes support for standard attributes
xml:lang and xml:srclang. See "XML Translations" on page 7-17.
See Also: Oracle Database PL/SQL Packages and Types Reference for
information about new PL/SQL package DBMS_XMLTRANSLATIONS

Support for Large XML Nodes
The previous 64K limit on text nodes and attribute values has been lifted. Text nodes
and attribute values are no longer limited in size to 64K bytes each. New streaming
push and pull APIs are available in PL/SQL, Java, and C to provide virtually
unlimited node sizes. See "Large Node Handling using DBMS_XMLDOM" on
page 13-12 for information about handling large nodes in PL/SQL and "Handling
Large Nodes using Java" on page 15-16.

lv

See Also:
■

■

■

Oracle Database SQL Language Reference for information about
creating XMLType tables and columns stored as binary XML
Oracle Database XML Java API Reference for information about new
Java methods
Oracle Database PL/SQL Packages and Types Reference for
information about new PL/SQL package DBMS_SDA and updates
to PL/SQL package DBMS_XMLDOM

Unified Java API
The Java XML APIs in Oracle XML DB and Oracle XML Developer's Kit have been
unified.
See Also:
■
■

Oracle XML Developer's Kit Programmer's Guide
Oracle Database XML Java API Reference, package
oracle.xml.parser.v2

Oracle Data Pump Support for XMLType
Oracle Data Pump is now the recommended way to import and export XMLType data.
See Chapter 36, "Exporting and Importing XMLType Tables".
Support for XMLType by Oracle Streams and Logical Standby
Oracle Streams and logical standby now support XMLType stored as CLOB. Both XML
schema-based and non-schema-based XML data are supported.
See Also:
■

Oracle Streams Concepts and Administration

■

Oracle Data Guard Concepts and Administration

■

Oracle Database Utilities

■

Oracle Database Reference for information on views DBA_
STREAMS_UNSUPPORTED and DBA_STREAMS_COLUMNS

Oracle XML Developer's Kit Pull-Parser API (XML Events, JSR-173)
You can use the new Oracle XML Developer Kit (XDK) pull-parser API with Oracle
XML DB. See "Using the Oracle XML Developer's Kit Pull Parser with Oracle
XML DB" on page 16-9.
See Also:
■

■

Oracle Database XML C API Reference for information about new C
methods and types
Oracle XML Developer's Kit Programmer's Guide

XQuery Standard Compliance
Oracle XML DB support for the XQuery language has been updated to reflect the latest
version of the XQuery standard, W3C XQuery 1.0 Recommendation.

lvi

See Also:
■
■

Oracle XML Developer's Kit Programmer's Guide
http://www.w3.org for information about the XQuery
language

Fine-Grained Access to Network Services Using PL/SQL
New atomic privileges are provided for access control entries (ACEs). These privileges
are used for fine-grained PL/SQL access to network services.
SQL/XML Standard Compliance and Performance Enhancements
Oracle XML DB support for the SQL/XML standard has been updated to reflect the
latest version of the standard. This includes support for standard SQL functions
XMLExists and XMLCast. See "Querying XMLType Data using SQL/XML Functions
XMLExists and XMLCast" on page 4-2 and "Generating XML using SQL Functions" on
page 18-2.
See Also: Oracle Database SQL Language Reference for information
about SQL/XML functions XMLExists, XMLCast, XMLQuery,
XMLTable, and XMLForest.

XML-Update Performance Enhancements
The performance of SQL functions used to update XML data has been enhanced for
XML schema-based data that is stored object-relationally. This includes XPath rewrite
for SQL functions updateXML, insertChildXML, and deleteXML.
XQuery and SQL/XML Performance Enhancements
XQuery and SQL/XML performance enhancements include treatment of the
following:
■

User-defined XQuery functions

■

XQuery prolog variables

■

XQuery count function applied to the result of using a SQL/XML generation
function

■

Positional expressions in XPath predicates

■

XQuery computed constructors

■

SQL/XML function XMLAgg

XSLT Performance Enhancements
The performance of XSLT transformations using SQL function XMLTransform and
XMLType method transform() has been enhanced.

lvii

lviii

Part I
Oracle XML DB Basics
Part I of this manual introduces Oracle XML DB. It contains the following chapters:
■

Chapter 1, "Introduction to Oracle XML DB"

■

Chapter 2, "Getting Started with Oracle XML DB"

■

Chapter 3, "Using Oracle XML DB"

1
Introduction to Oracle XML DB
This chapter introduces the features and architecture of Oracle XML DB. It contains
these topics:
■

Overview of Oracle XML DB

■

Oracle XML DB Architecture

■

Oracle XML DB Features

■

Oracle XML DB Benefits

■

Search XML Data using Oracle Text

■

Build Messaging Applications using Oracle Streams Advanced Queuing

■

Standards Supported by Oracle XML DB

■

Oracle XML DB Technical Support

■

Oracle XML DB Examples Used in This Manual

■

Further Oracle XML DB Case Studies and Demonstrations

Overview of Oracle XML DB
Oracle XML DB is a set of Oracle Database technologies related to high-performance
handling of XML data: storing, generating, accessing, searching, validating,
transforming, evolving, and indexing. It provides native XML support by
encompassing both the SQL and XML data models in an interoperable way. Oracle
XML DB is included as part of Oracle Database starting with Oracle9i Release 2 (9.2).
Oracle XML DB includes the following features:
■
■

■

■

■

An abstract SQL data type, XMLType, for XML data.
Enterprise-level Oracle Database features for XML content: reliability, availability,
scalability, and security. XML-specific memory management and optimizations.
Industry-standard ways to access and update XML data. The standards include
the SQL/XML standard and the World Wide Web Consortium (W3C) XML and
XML Schema data models and recommendations for XPath and XQuery. You can
use FTP, HTTP(S), and WebDAV to move XML content into and out of Oracle
Database. Industry-standard APIs provide programmatic access and manipulation
of XML content using Java, C, and PL/SQL.
Ways to store, query, update, and transform XML data while accessing it using
SQL.
Ways to perform XML operations on SQL data.

Introduction to Oracle XML DB 1-1

Oracle XML DB Architecture

■

■

■

Oracle XML DB Repository: a simple, lightweight repository where you can
organize and manage database content, including XML content, using a
file/folder/URL metaphor.
Ways to access and combine data from disparate systems through gateways, using
a single, common data model. This reduces the complexity of developing
applications that must deal with data from different stores.
Ways to use Oracle XML DB in conjunction with Oracle XML Developer's Kit
(XDK) to build applications that run in the middle tier in either Oracle Application
Server or Oracle Database.
See Also:
■
■

■

"XMLType Data Type" on page 1-12
http://www.oracle.com/technetwork/database-featur
es/xmldb/overview/index.html for the latest news and
white papers about Oracle XML DB
Oracle XML Developer's Kit Programmer's Guide

Oracle XML DB Architecture
Figure 1–1 and Figure 1–2 show the software architecture of Oracle XML DB. The main
features are:
■

■

■

Storage of XMLType tables and views.
–

You can index XMLType tables and views using XMLIndex, B-tree, and Oracle
Text indexes.

–

You can store data that is in XMLType views in local or remote tables. You can
access remote tables using database links.

Oracle XML DB Repository. You can store any kind of documents in the repository,
including XML documents that are associated with an XML schema that is
registered with Oracle XML DB. You can access documents in the repository in any
of the following ways:
–

HTTP(S), through the HTTP protocol handler

–

WebDAV and FTP, through the WebDAV and FTP protocol handlers

–

SQL, through Oracle Net Services, including Java Database Connectivity
(JDBC)

Support of XML data messaging using Oracle Streams Advanced Queuing (AQ)
and Web Services.

1-2 Oracle XML DB Developer's Guide

Oracle XML DB Architecture

Figure 1–1 XMLType Storage and Oracle XML DB Repository
Browser
or other
UI

Browser

JDBC
Application

Desktop
Tool

FTP
Tool

Direct
HTTP
Access

Oracle
Net
Services
Access

WebDAV
Access

FTP
Access

Oracle
Streams
AQ Access

Oracle Database
Gateways
to external
sources

Oracle XML DB
XMLType Tables
and Views

XML Services
• XML Validation
• XML Transformation
• XML Schema
Registration
• Create Tables
• Insert, Delete, Update
XMLType tables
• Indexing

Retrieve / Generate
XML Using
XMLType APIs
• SQL
• Java
• PL/SQL
• C
• C++

Oracle XML DB
Repository

XML Services
• Versioning
• ACL Security
• Foldering
Retrieve / Generate XML
Using Resource APIs
• SQL
• Java
• PL / SQL

Introduction to Oracle XML DB 1-3

Oracle XML DB Architecture

Figure 1–2 XMLType Storage
JDBC

Direct
HTTP
Access

Oracle
Net
Access

WebDAV Access
and
FTP Access
Oracle
Streams
AQ Access

Oracle
Database
Oracle XML DB
HTTP
Protocol
Handler

SQL
Engine

DAV, FTP
Protocol
Handlers

XML Schemas

Indexes:
• XMLIndex
• B-Tree
• FunctionBased
• Oracle Text

XMLType
Tables

XMLType
Views

Repository

Hierarchical
Index

Binary XML
Storage
Unstructured Storage
(CLOB)

Local
Tables

DBLinks

Remote
Tables
Accessed
via DBLinks

Structured Storage
(Object Relational)

See Also:
■

Part II, "Storing and Retrieving XML Data in Oracle XML DB"

■

Chapter 28, "Accessing the Repository using Protocols"

■

Chapter 37, "Exchanging XML Data using Oracle Streams AQ"

APIs for XML
Table 1–1 lists the reference documentation for the PL/SQL, C, and C++ Application
Programming Interfaces (APIs) that you can use to manipulate XML data. The main
reference for PL/SQL, C, and C++ APIs is Oracle Database PL/SQL Packages and Types
Reference.

1-4 Oracle XML DB Developer's Guide

Oracle XML DB Architecture

See Also: Oracle Database XML Java API Reference for information
about Java APIs for XML
Table 1–1

APIs Related to XML

API

Documentation

Description

XMLType

Oracle Database PL/SQL Packages and PL/SQL, C, and C++ APIs with XML operations on
Types Reference, Chapter "XMLType", XMLType data – validation, transformation.
Oracle Database XML C API
Reference, and Oracle Database XML
C++ API Reference

Database URI types

Oracle Database PL/SQL Packages and Functions used for various URI types.
Types Reference, Chapter "Database
URI TYPEs"

DBMS_METADATA

Oracle Database PL/SQL Packages and PL/SQL API for retrieving metadata from the
Types Reference, Chapter "DBMS_
database dictionary as XML, or retrieving creation
METADATA"
DDL and submitting the XML to re-create the
associated object.

DBMS_RESCONFIG

Oracle Database PL/SQL Packages and PL/SQL API to operate on a resource configuration
Types Reference, Chapter "DBMS_
list, and to retrieve listener information for a
RESCONFIG"
resource.

DBMS_XDB

Oracle Database PL/SQL Packages and PL/SQL API for managing Oracle XML DB
Types Reference, Chapter "DBMS_
Repository resources, ACL-based security, and
XDB"
configuration sessions.

DBMS_XDB_ADMIN

Oracle Database PL/SQL Packages and PL/SQL API for managing miscellaneous features
of Oracle XML DB, including the XMLIndex index
Types Reference, Chapter "DBMS_
on the Oracle XML DB Repository.
XDB_ADMIN"

DBMS_XDBRESOURCE

Oracle Database PL/SQL Packages and PL/SQL API to operate on repository resource
Types Reference, Chapter "DBMS_
metadata and contents.
XDBRESOURCE"

DBMS_XDBT

Oracle Database PL/SQL Packages and PL/SQL API for creation of text indexes on
Types Reference, Chapter "DBMS_
repository resources.
XDBT"

DBMS_XDB_VERSION

Oracle Database PL/SQL Packages and PL/SQL API for version management of repository
resources.
Types Reference, Chapter "DBMS_
XDB_VERSION"

DBMS_XDBZ

Oracle Database PL/SQL Packages and Oracle XML DB Repository ACL-based security.
Types Reference, Chapter "DBMS_
XDBZ"

DBMS_XEVENT

Oracle Database PL/SQL Packages and PL/SQL API providing event-related types and
Types Reference, Chapter "DBMS_
supporting interface.
XEVENT"
.

DBMS_XMLDOM

Oracle Database PL/SQL Packages and PL/SQL implementation of the DOM API for
Types Reference, Chapter "DBMS_
XMLType.
XMLDOM"

DBMS_XMLGEN

Oracle Database PL/SQL Packages and PL/SQL API for transformation of SQL query
Types Reference, Chapter "DBMS_
results into canonical XML format.
XMLGEN"

DBMS_XMLINDEX

Oracle Database PL/SQL Packages and PL/SQL API for XMLIndex.
Types Reference, Chapter "DBMS_
XMLINDEX

DBMS_XMLPARSER

Oracle Database PL/SQL Packages and PL/SQL implementation of the DOM Parser API
Types Reference, Chapter "DBMS_
for XMLType.
XMLPARSER"

Introduction to Oracle XML DB 1-5

Oracle XML DB Architecture

Table 1–1 (Cont.) APIs Related to XML
API

Documentation

Description

DBMS_XMLSCHEMA

Oracle Database PL/SQL Packages and PL/SQL API for managing XML schemas within
Oracle Database – schema registration, deletion.
Types Reference, Chapter "DBMS_
XMLSCHEMA

DBMS_XMLSTORE

Oracle Database PL/SQL Packages and PL/SQL API for storing XML data in relational
tables.
Types Reference, Chapter "DBMS_
XMLSTORE"

DBMS_XSLPROCESSOR Oracle Database PL/SQL Packages and PL/SQL implementation of an XSLT processor.
Types Reference, Chapter "DBMS_
XSLPROCESSOR"

Catalog Views Related to XML
Table 1–2 lists the catalog views related to XML. Information about a given view can
be obtained by using SQL command DESCRIBE.
DESCRIBE USER_XML_SCHEMAS
Table 1–2

Catalog Views Related to XML

Schema

Description

USER_XML_SCHEMAS

Registered XML schemas owned by the current user

ALL_XML_SCHEMAS

Registered XML schemas usable by the current user

DBA_XML_SCHEMAS

Registered XML schemas in Oracle XML DB

USER_XML_TABLES

XMLType tables owned by the current user

ALL_XML_TABLES

XMLType tables usable by the current user

DBA_XML_TABLES

XMLType tables in Oracle XML DB

USER_XML_TAB_COLS

XMLType table columns owned by the current user

ALL_XML_TAB_COLS

XMLType table columns usable by the current user

DBA_XML_TAB_COLS

XMLType table columns in Oracle XML DB

USER_XML_VIEWS

XMLType views owned by the current user

ALL_XML_VIEWS

XMLType views usable by the current user

DBA_XML_VIEWS

XMLType views in Oracle XML DB

USER_XML_VIEW_COLS XMLType view columns owned by the current user
ALL_XML_VIEW_COLS

XMLType view columns usable by the current user

DBA_XML_VIEW_COLS

XMLType view columns in Oracle XML DB

In addition to the views ALL_XML_TABLES, DBA_XML_TABLES, and USER_XML_
TABLES, views ALL_OBJECT_TABLES, DBA_OBJECT_TABLES, and USER_OBJECT_
TABLES provide tablespace and other storage information for XMLType data stored
object-relationally.
See Also:
■

Oracle Database Reference

■

Oracle Database PL/SQL Packages and Types Reference

1-6 Oracle XML DB Developer's Guide

Oracle XML DB Architecture

Overview of Oracle XML DB Repository
Oracle XML DB Repository is a component of Oracle Database that lets you handle
XML data using a file/folder/URL metaphor. The repository contains resources,
which can be either folders (directories, containers) or files.
A resource has these properties:
■

It is identified by a path and name.

■

It has content (data), which can be XML data but need not be.

■

■

■

It has a set of system-defined metadata (properties), such as Owner and
CreationDate, in addition to its content. Oracle XML DB uses this information
to manage the resource.
It might also have user-defined metadata. Like system-defined metadata, this is
information that is not part of the content, but is associated with it.
It has an associated access control list that determines who can access the
resource, and for what operations.

Although Oracle XML DB Repository treats XML content specially, you can use the
repository to store other kinds of data besides XML. You can use the repository to
access any data that is stored in Oracle Database.
You can access data in the repository in the following ways (see Figure 1–1):
■

SQL – Using views RESOURCE_VIEW and PATH_VIEW

■

PL/SQL – Using package DBML_XDB

■

Java – Using the Oracle XML DB resource API for Java
See Also:
■
■

■

Part V. "Oracle XML DB Repository"
Chapter 28, "Accessing the Repository using Protocols" for
information about accessing XML data in XMLType tables and
columns using external protocols
Chapter 29, "User-Defined Repository Metadata"

XML Services
Besides providing APIs for accessing and manipulating repository data, Oracle
XML DB provides APIs for the following repository services:
■

■

■

Versioning – Oracle XML DB uses PL/SQL package DBMS_XDB_VERSION to
version resources in Oracle XML DB Repository. Updating a resource creates a
new version. Previous versions are retained. Versioning support is based on the
IETF WebDAV standard.
ACL Security – Repository security is based on access control lists (ACLs). Each
resource has an associated ACL that lists the privileges required to use it in
various ways. When a resource is accessed or manipulated, its ACL determines
whether the requested operation is allowed. An ACL is an XML document that
contains a set of access control entries (ACEs). Each ACE grants or revokes a set of
permissions to a particular user or group (database role). This access control
mechanism is based on the WebDAV specification.
Foldering – Oracle XML DB Repository manages a persistent hierarchy of folder
(that is, directory) resources that contain other resources (files or folders). Oracle
XML DB modules such as protocol servers, the XML schema manager, and the
Introduction to Oracle XML DB 1-7

Oracle XML DB Architecture

Oracle XML DB RESOURCE_VIEW API use foldering to map repository path
names to the resources they target.

Views RESOURCE_VIEW and PATH_VIEW
Views RESOURCE_VIEW and PATH_VIEW provide SQL access to data in Oracle
XML DB Repository through protocols such as FTP and WebDAV. View PATH_VIEW
has one row for each unique path in the repository. View RESOURCE_VIEW has one
row for each resource in the repository.
The Oracle XML DB resource API for PL/SQL, DBMS_XDB, provides query and DML
functions. It is based on RESOURCE_VIEW and PATH_VIEW.
See Also:
■

■

■

Chapter 25, "Accessing the Repository using RESOURCE_
VIEW and PATH_VIEW"
Oracle Database Reference for more information about view
PATH_VIEW
Oracle Database Reference for more information about view
RESOURCE_VIEW

Oracle XML DB Repository Architecture
Figure 1–3 illustrates the architecture of Oracle XML DB Repository.
See Also:
■
■

Chapter 21, "Accessing Oracle XML DB Repository Data"
Chapter 25, "Accessing the Repository using RESOURCE_
VIEW and PATH_VIEW"

1-8 Oracle XML DB Developer's Guide

Oracle XML DB Architecture

Figure 1–3 Oracle XML DB Repository Architecture
Application Logical View of
Oracle XML DB Repository
Table
Name

ACL

Property 1

Property N

Property N

abc

Oracle Database

XMLType
Rows

Database View of Oracle XML DB Repository
RESOURCE_VIEW (XMLType)
Name

ACL

Property 1

Property N

Path
Extra

Content

Parent

LOB
FTP
WebDAV

XMLIndex
Index

B-Tree
Index

Function-Based
Index

Oracle Text
Index

Hierarchical
Index

Tables or
Views
of XML

Files and Folders
Relational databases are traditionally poor at managing hierarchical structures and
traversing a path or a URL. Oracle XML DB Repository provides you with a
hierarchical organization of XML content in the database. You can query and manage
it as if it were organized using files and folders.
The relational table-row-column metaphor is an effective model for managing highly
structured data. It can be less effective for managing semi-structured and unstructured
data, such as document-oriented XML data.
For example, a book is not easily represented as a set of rows in a table. It might be
more natural to represent a book as a hierarchy, book—chapter—section—paragraph,
and to represent the hierarchy as a set of folders and subfolders.
■

■

■

A hierarchical repository index speeds up folder and path traversals. Oracle
XML DB includes a patented hierarchical index that speeds up folder and path
traversals in Oracle XML DB Repository. The hierarchical repository index is
transparent to end users, and lets Oracle XML DB perform folder and path
traversals at speeds comparable to or faster than conventional file systems.
You can access XML documents in Oracle XML DB Repository using standard
connect-access protocols such as FTP, HTTP(S), and WebDAV, in addition to
languages SQL, PL/SQL, Java, and C. The repository provides content authors
and editors direct access to XML content stored in Oracle Database.
A resource in this context is a file or folder, identified by a URL. WebDAV is an
IETF standard that defines a set of extensions to the HTTP protocol. It lets an
Introduction to Oracle XML DB 1-9

Oracle XML DB Architecture

HTTP server act as a file server for a DAV-enabled client. For example, a
WebDAV-enabled editor can interact with an HTTP/WebDAV server as if it were a
file system. The WebDAV standard uses the term resource to describe a file or a
folder. Each resource managed by a WebDAV server is identified by a URL. Oracle
XML DB adds native support to Oracle Database for these protocols. The protocols
were designed for document-centric operations. By providing support for these
protocols, Oracle XML DB lets Microsoft Windows Explorer, Microsoft Office, and
products from vendors such as Altova and Adobe work directly with XML content
stored in Oracle XML DB Repository. Figure 1–4 shows the root-level directory of
the repository as seen from a Web browser.
Figure 1–4 Web Browser View of Oracle XML DB Repository

See Also:

Chapter 3, "Using Oracle XML DB"

Hence, WebDAV clients such as Microsoft Windows Explorer can connect directly to
Oracle XML DB Repository. No additional Oracle Database or Microsoft-specific
software or other complex middleware is needed. End users can work directly with
Oracle XML DB Repository using familiar tools and interfaces.

Oracle XML DB Protocol Architecture
One key feature of the Oracle XML DB architecture is that protocols HTTP(S),
WebDAV, and FTP are supported, including in a shared server configuration. When
the Listener receives an HTTP(S) or FTP request, it hands it off to an Oracle Database
shared server process which services it and sends the appropriate response back to the
client.
You can use the TNS Listener command, lsnrctl status, to verify that HTTP(S)
and FTP support has been enabled. Example 1–1 illustrates this.
Example 1–1 Listener Status with FTP and HTTP(S) Protocol Support Enabled
LSNRCTL for 32-bit Windows: Version 11.1.0.5.0 - Production on 20-AUG-2007 16:02:34

1-10 Oracle XML DB Developer's Guide

Oracle XML DB Architecture

Copyright (c) 1991, 2007, Oracle.

All rights reserved.

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1521))) STATUS of the LISTENER
-------------------------------------------------------------------------------------------Alias
LISTENER
Version
TNSLSNR for 32-bit Windows: Version 11.1.0.5.0 - Beta
Start Date
20-JUN-2007 15:35:40
Uptime
0 days 16 hr. 47 min. 42 sec
Trace Level
off
Security
ON: Local OS Authentication
SNMP
OFF
Listener Parameter File
C:\oracle\product\11.1.0\db_1\network\admin\listener.ora
Listener Log File
c:\oracle\diag\tnslsnr\quine-pc\listener\alert\log.xml
Listening Endpoints Summary...
(DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(PIPENAME=\\.\pipe\EXTPROC1521ipc)))
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=quine-pc.example.com)(PORT=1521)))
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=quine-pc.example.com)
(PORT=21))(Presentation=FTP)(Session=RAW))
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=quine-pc.example.com)
(PORT=443))(Presentation=HTTP)(Session=RAW))
Services Summary...
Service "orcl.example.com" has 1 instance(s).
Instance "orcl", status READY, has 1 handler(s) for this service...
Service "orclXDB.example.com" has 1 instance(s).
Instance "orcl", status READY, has 1 handler(s) for this service...
Service "orcl_XPT.example.com" has 1 instance(s).
Instance "orcl", status READY, has 1 handler(s) for this service...
The command completed successfully

See Also:

Chapter 28, "Accessing the Repository using Protocols"

Programmatic Access to Oracle XML DB (Java, PL/SQL, and C)
All Oracle XML DB functionality is accessible from C, PL/SQL, and Java. You can
build Web-based applications in various ways, including these:
■

■

Using servlets and Java Server Pages (JSP). A typical API accesses data using Java
Database Connectivity (JDBC).
Using Extensible Stylesheet Language (XSL) plus XML Server Pages (XSP). A
typical API accesses data in the form of XML documents that are processed using
a Document Object Model (DOM) API implementation.

Oracle XML DB supports such styles of application development. It provides Java,
PL/SQL, and C implementations of the DOM API.
Applications that use JDBC, such as those based on servlets, need prior knowledge of
the data structure they are processing. Oracle JDBC drivers allow you to access and
update XMLType tables and columns, and call PL/SQL procedures that access Oracle
XML DB Repository.
Applications that use DOM, such as those based on XSLT transformations, typically
require less knowledge of the data structure. DOM-based applications use string
names to identify pieces of content, and must dynamically walk through the DOM tree
to find the required information. For this, Oracle XML DB supports the use of the
DOM API to access and update XMLType columns and tables. Programming to a DOM
API is more flexible than programming through JDBC, but it may require more
resources at run time.

Introduction to Oracle XML DB 1-11

Oracle XML DB Features

Oracle XML DB Features
Any database used for managing XML must be able to persist XML documents. Oracle
XML DB is capable of much more than this. It provides standard database features
such as transaction control, data integrity, replication, reliability, availability, security,
and scalability, while also allowing for efficient indexing, querying, updating, and
searching of XML documents in an XML-centric manner.
The hierarchical nature of XML presents the traditional relational database with some
challenges:
■

■

In a relational database, the table-row metaphor locates content. Primary-Key
Foreign-Key relationships help define the relationships between content. Content
is accessed and updated using the table-row-column metaphor.
XML, on the other hand, uses hierarchical techniques to achieve the same
functionality. A URL is used to locate an XML document. URL-based standards
such as XLink are used to define relationships between XML documents. W3C
Recommendations such as XPath are used to access and update content contained
within XML documents. Both URLs and XPath expressions are based on
hierarchical metaphors. A URL uses a path through a folder hierarchy to identify a
document, whereas XPath uses a path through the node hierarchy of an XML
document to access part of an XML document.

Oracle XML DB addresses these challenges by introducing SQL functions and methods
that allow the use of XML-centric metaphors, such as XQuery and XPath expressions
for querying and updating XML Documents.
These are the major features of Oracle XML DB:
■

XMLType Data Type

■

XML Schema Support

■

XMLType Storage Models

■

XML/SQL Duality

■

SQL/XML Standard Functions

■

Automatic Rewriting of XQuery and XPath Expressions

■

Overview of Oracle XML DB Repository. This was described on page 1-7.

XMLType Data Type
XMLType is an abstract native SQL data type for XML data. It provides methods that
allow operations such as XML Schema validation and XSL transformation of XML
content. You can use XMLType as you would any other SQL data type. For example,
you can use XMLType when you do any of the following:
■

Create a column in a relational table

■

Declare a PL/SQL variable

■

Define or call a PL/SQL procedure or function

XMLType is an Oracle Database object type, so you can also create a table of XMLType
object instances. By default, an XMLType table or column can contain any well-formed
XML document.

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Oracle XML DB Features

See Also: Oracle Database Object-Relational Developer's Guide for
information about Oracle Database object types and object-relational
storage

XMLType Tables and Columns Can Conform to an XML Schema
XMLType tables or columns can be constrained to conform to an XML schema. This
has several advantages:
■

■

■

The database ensures that only XML documents that validate against the XML
schema are stored in the column or table. Invalid documents are excluded.
Because XML schema-based data conforms to a predefined XML structure, Oracle
XML DB can use the information contained in the XML schema to optimize
querying and updating of the data.
If you store XML schema-based data using structured storage, Oracle XML DB
automatically decomposes it and stores it as a set of object-relational objects. The
object-relational model used to store the document is derived from the XML
schema.

XMLType API
Data type XMLType provides the following:
■

■

Constructors, which you can use to create an XMLType instance from a VARCHAR,
CLOB, BLOB, or BFILE value.
XML-specific methods that operate on XMLType instances. These include the
following:
■
■

■

■

extract()– Extract a subset of nodes contained in the XMLType instance.
existsNode() – Check whether or not a particular node exists in the
XMLType instance.
schemaValidate() – Validate the content of the XMLType instance against
an XML schema.
transform() – Perform an XSL transformation on the content of an
XMLType instance.
See Also: Chapter 4, "XMLType Operations" and Chapter 11,
"Transforming and Validating XMLType Data"

XML Schema Support
Support for the Worldwide Web Consortium (W3C) XML Schema Recommendation is
a key feature in Oracle XML DB. XML Schema specifies the structure, content, and
certain semantics of XML documents. It is described in detail at
http://www.w3.org/TR/xmlschema-0/.
The W3C Schema Working Group publishes a particular XML schema, often referred
to as the schema for schemas, that provides the definition, or vocabulary, of the XML
Schema language. An XML schema definition (XSD1), also called an XML schema, is
an XML document that is compliant with the vocabulary defined by the schema for
schemas.

1

xsd is the prefix used in the schema of schemas for the XML Schema namespace, hence it is
also the namespace prefix used for the XML Schema data types, such as xsd:string. xsd is
also used often as the file extension of XML schema files.

Introduction to Oracle XML DB 1-13

Oracle XML DB Features

An XML schema uses vocabulary defined by the schema for schemas to create a
collection of XML Schema type definitions and element declarations that comprise a
vocabulary for describing the contents and structure of a new class of XML
documents, the XML instance documents that conform to that XML schema.
This manual uses the term "XML schema" (lower-case "s") to
reference any XML schema that conforms to the W3C XML Schema
(upper-case "S") Recommendation. Since an XML schema is used to
define a class of XML documents, the term "instance document" is
often used to describe an XML document that conforms to a
particular XML schema.

Note:

The XML Schema language provides strong typing of elements and attributes. It
defines numerous scalar data types. This base set of data types can be extended to
define more complex types, using object-oriented techniques such as inheritance and
extension. The XML Schema vocabulary also includes constructs that you can use to
define complex types, substitution groups, repeating sets, nesting, ordering, and so on.
Oracle XML DB supports all of the constructs defined by the XML Schema
Recommendation, except for redefines.
XML schemas are commonly used as a mechanism for checking (validating) whether
XML instance documents conform with their specifications. Oracle XML DB includes
XMLType methods and SQL functions that you can use to validate XML documents
against an XML schema.
In Oracle XML DB, you can use a standard data model for all of your data, regardless
of how structured it is. You can use XML Schema to automatically create database
tables for storing your XML data. XML schema-based data maintains DOM fidelity
and allows for significant database optimizations.
XML schema-based data can be stored using any Oracle XML DB XMLType storage
model: binary XML storage, structured (object-relational) storage, or unstructured
(CLOB) storage. Non-schema-based XML data can be stored using binary XML storage
or unstructured storage.
You can also wrap existing relational and object-relational data as XMLType views,
which can optionally be XML schema-based. You can map from incoming XML
documents to XMLType storage, specifying the mapping using a registered XML
schema.
See Also: Chapter 7, "XML Schema Storage and Query: Basic" for
more information about using XML schemas with Oracle XML DB

XMLType Storage Models
XMLType is an abstract data type that provides different storage models to best fit your
data and your use of it. As an abstract data type, your applications and database
queries gain in flexibility: the same interface is available for all XMLType operations.
Because different storage (persistence) models are available, you can tailor
performance and functionality to best fit the kind of XML data you have and the
pattern of its use. One key decision to make when using Oracle XML DB for persisting
XML data as XMLType is thus which storage model to use for which XML data.
You can change XMLType storage from one model to another, using database
import/export (see Chapter 36, "Exporting and Importing XMLType Tables"). Your
application code need not change. You can change XML storage options when tuning
your application.
1-14 Oracle XML DB Developer's Guide

Oracle XML DB Features

XMLType tables and columns can be stored in these ways:
■

■

■

Structured storage – XMLType data is stored as a set of objects. This is also
referred to as object-relational storage and object-based persistence.
Unstructured storage – XMLType data is stored in Character Large Object (CLOB)
instances. This is also referred to as CLOB storage and text-based persistence.
Binary XML storage – XMLType data is stored in a post-parse, binary format
specifically designed for XML data. Binary XML is compact, post-parse, XML
schema-aware XML. This is also referred to as post-parse persistence.

Oracle Database provides two LOB storage options, SecureFile and BasicFile. Either of
these can be used with unstructured (CLOB-based) XMLType storage. BasicFile LOB
storage is the default for unstructured storage.
For binary XML data, SecureFile is the default storage option.2 However, if either of
the following is true then it is not possible to use SecureFile LOB storage. In that case,
BasicFile is the default option for binary XML data:
■

■

The tablespace for the XMLType table does not use automatic segment space
management.
A setting in file init.ora prevents SecureFile LOB storage. For example, see
parameter DB_SECUREFILE.
See Also:
■

■

■

■

Oracle Database SQL Language Reference, section "CREATE TABLE",
clause "LOB_storage_clause"
Oracle Database SecureFiles and Large Objects Developer's Guide for
information about LOB storage options SecureFile and BasicFile
Oracle Database Administrator's Guide for information about
automatic segment space management
Oracle Database Reference for information about parameter DB_
SECUREFILE

You can mix storage models, using one model for one part of an XML document and a
different model for another part. The mixture of structured and unstructured storage is
sometimes called hybrid storage. What is true about structured storage is true about
the structured part of hybrid storage. What is true about unstructured storage is true
about the unstructured part of hybrid storage.
XMLType has multiple storage models, and some models can be configured in more
than one way. Each model has its advantages, depending on the context. Each model
has one or more types of index that are appropriate for it.
The first thing to consider, when choosing an XMLType storage model, is the nature of
your XML data and the ways you use it. A spectrum exists, with data-centric use of
highly structured data at one end, and document-centric use of highly unstructured
data at the other. The first question to ask yourself is this: Is your use case primarily
data-centric or document-centric?
■

2

Data-centric – Your data is, in general, highly structured, with relatively static and
predictable structure, and your applications take advantage of this structure. Your
data conforms to an XML schema.
Prior to Oracle Database 11g Release 2 (11.2.0.2) the BasicFile option was the default for binary
XML storage. Use of the BasicFile option for binary XML data is deprecated.

Introduction to Oracle XML DB 1-15

Oracle XML DB Features

■

Document-centric – Two cases:
–

Your data is generally without structure or of variable structure. Document
structure can vary over time (evolution). Content is mixed (semi-structured):
many elements contain both text nodes and child elements. Many XML
elements can be absent or can appear in different orders. Documents might or
might not conform to an XML schema.

–

Your data relatively structured, but your applications do not take advantage of
that structure: they treat the data as if it were without structure.
Please be aware of the context, so as not to confuse discussion
of storage options with discussion of the structure of the XML content
to be stored. In this book, "structured" and "unstructured" generally
refer to XMLType storage options. They refer less often to the nature of
your data. "Hybrid" refers to object-relational storage with some
embedded CLOB storage. "Semi-structured" refers to XML content,
regardless of storage. Unstructured storage is CLOB-based storage,
and structured storage is object-relational storage.

Note:

Once you've located the data-centric or document-centric half of the spectrum that is
appropriate for your use case and data, consider whether your case is at an end of the
spectrum or closer to the middle. That is, just how data-centric or document-centric is
your case?
■

■

■

Employ object-relational (structured) storage for purely data-centric uses. A typical
example of this use case would be an employee record (fields employee number,
name, address, and so on). Use B-tree indexing with object-relational storage.
Employ hybrid storage if your data is composed primarily of invariable XML
structures, but it does contain some variable data; that is, it contains a predictably
few mixed-content elements. A typical example of this use case would be an
employee record that includes a free-form resume. Index the structured and
unstructured parts of your data separately, using appropriate indexes for each
part.
Employ binary XML storage or CLOB-based (unstructured) storage for all
document-centric use cases. XMLIndex is the indexing method of choice here.
–

For general indexing of document-centric XML data, use XMLIndex indexes
with unstructured components. A typical example of this use case would be
an XML Web document or a book chapter.

–

If your data contains some predictable, fixed structures that you query
frequently, then you can use XMLIndex indexes with structured components
on those parts. A typical example of this use case would be a free-form
specification, with author, date, and title fields.

A single XMLIndex index can have both structured and unstructured components,
to handle islands of structure within generally unstructured content. A use case
where you might use both components would be to support queries that extract an
XML fragment from a document whenever some structured data is present. The
unstructured index component is used for the fragment extraction. The structured
component is used for the SQL WHERE clause that checks for the structured data.
In all cases, you can additionally use Oracle Text indexing for full-text queries. This is
especially useful for document-centric cases.

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Oracle XML DB Features

These considerations are summarized in Figure 1–5. The figure shows the spectrum of
use cases, from most data-centric, at the left, to most document-centric, at the right.
The table in the figure classifies use cases and shows the corresponding storage
models and indexing methods.
Figure 1–5 XML Use Cases and XMLType Storage Models

Data-Centric

Document-Centric

Use Case

XML schema-based data,
with little variation and
little structural change
over time

XML schema-based
data, with some
embedded variable
data

Variable, free-form data,
with some fixed
embedded structures

Variable, free-form
data

Typical Data

Employee record

Employee record that
includes a free-form
resume

Technical article, with
author, date, and title
fields

Web document or
book chapter

Storage Model

Object-Relational
(Structured)

Hybrid

CLOB (Unstructured) or Binary XML

Indexing

B-tree index

·
·

XMLIndex index with
structured and
unstructured components

B-tree index
XMLIndex index with
unstructured component

XMLIndex index with
unstructured
component

See Chapter 6, "Indexing XMLType Data" for more information about indexing XML
data. In particular, note that some types of indexing are complementary or orthogonal,
so you can use them together.
The following list and Table 1–3 outline some of the advantages of each storage model.
■

■

■

Structured (object-relational) storage advantages over the other storage models
include near-relational query and update performance, optimized memory
management, reduced storage requirements, B-tree indexing, and in-place
updates. These advantages are at a cost of increased processing overhead during
ingestion and full retrieval of XML data, and reduced flexibility in the structure of
the XML that can be managed by a given XMLType table or column. Structural
flexibility is reduced because data and metadata (such as column names) are
separated in object-relational storage. Instance structures cannot vary easily.
Structured storage is particularly appropriate for highly structured data whose
structure does not vary, if this maps to a manageable number of database tables
and joins.
Unstructured (CLOB) storage enables higher throughput than structured storage
when inserting and retrieving entire XML documents. No data conversion is
needed, so the same format can be used outside the database. Unstructured
storage also provides greater flexibility than structured storage in the structure of
the XML that can be stored. Unstructured storage is particularly appropriate for
document-centric use cases. These advantages can come at the expense of certain
aspects of intelligent processing: in the absence of indexing, there is little that the
database can do to optimize queries or updates on XML data that is stored in a
CLOB instance. In particular, the cost of XML parsing (often implicit) can
significantly impact query performance. Indexing with XMLIndex can improve
the performance of queries against unstructured storage.
Binary XML storage provides more efficient database storage, updating, indexing,
and fragment extraction than unstructured storage. It can provide better query
performance than unstructured storage—it does not suffer from the XML parsing

Introduction to Oracle XML DB 1-17

Oracle XML DB Features

bottleneck (it is a post-parse persistence model). Like structured storage, binary
XML storage is aware of XML Schema data types and can take advantage of native
database data types. Like structured storage, binary XML storage allows for
piecewise updates. Because binary XML data can also be used outside the
database, it can serve as an efficient XML exchange medium, and you can off load
work from the database to increase overall performance in many cases. Like
unstructured storage, binary XML data is kept in document order. Like structured
storage, data and metadata can, using binary storage, be separated at the database
level, for efficiency. Like unstructured storage, however, binary XML storage
allows for intermixed data and metadata, which lets instance structures vary.
Binary XML storage allows for very complex and variable data, which in the
structured-storage model could necessitate using many database tables. Unlike the
other XMLType storage models, you can use binary storage for XML schema-based
data even if the XML schema is not known beforehand, and you can store multiple
XML schemas in the same table and query across common elements.
Table 1–3

XMLType Storage Models: Relative Advantages
Structured (Object-Relational)
Storage

Binary XML Storage

Unstructured (CLOB) Storage

Throughput

– XML decomposition can result in
reduced throughput when ingesting or
retrieving the entire content of an XML
document.

+ High throughput. Fast DOM
loading. There is a slight
overhead from the binary XML
encoder/decoder.

++ High throughput when ingesting
and retrieving the entire content of
an XML document.

Queries

++ Extremely fast: relational query
performance.

+ Streaming XPath evaluation
avoids DOM construction and
allows evaluation of multiple
XPath expressions in a single
pass. Navigational XPath
evaluation is significantly faster
than with unstructured storage.

– XPath operations are evaluated by
constructing a DOM from the CLOB
data and using functional
evaluation. Expensive when
performing operations on large
documents or large collections of
documents.

XMLIndex indexing can
improve performance of
XPath-based queries.

XMLIndex indexing can improve
performance of XPath-based
queries.

Quality

You can create B-tree indexes on the
underlying object-relational columns.

Update
operations
(DML)

++ Extremely fast: relational columns
are updated in place.

+ In-place, piecewise update for
SecureFile LOB storage.

– When any part of the document is
updated, the entire document must
be written back to disk.

Space
efficiency
(disk)

++ Extremely space-efficient.

+ Space-efficient.

– Consumes the most disk space,
due to insignificant whitespace and
repeated tags.

Data flexibility – Limited flexibility. Only documents
that conform to the XML schema can
be stored in the XMLType table or
column.

+ Flexibility in the structure of the
+ Flexibility in the structure of
the XML documents that can be XML documents that can be stored
stored in an XMLType column or in an XMLType column or table.
table.

XML schema
flexibility

++ Can store XML
schema-based or
non-schema-based documents.
An XMLType table can store
documents that conform to any
registered XML schemas.

– An XMLType table can only store
documents that conform to the same
XML schema.
In-place XML schema evolution is
available, with some restrictions.

++ Can store XML schema-based or
non-schema-based documents.
Cannot use multiple XML schemas
for the same XMLType table.

XML fidelity

DOM fidelity: A DOM created from an DOM fidelity (see structured
XML document that has been stored in storage description).
the database is identical to a DOM
created from the original document.
However, insignificant whitespace
may be discarded.

+ Document fidelity: Maintains the
original XML data, byte for byte. In
particular, all original whitespace is
preserved.

Indexing
support

+ B-tree, bitmap, Oracle Text,
XMLIndex, and function-based
indexes.

XMLIndex, function-based, and
Oracle Text indexes.

1-18 Oracle XML DB Developer's Guide

XMLIndex, function-based, and
Oracle Text indexes.

Oracle XML DB Features

Table 1–3 (Cont.) XMLType Storage Models: Relative Advantages
Quality

Structured (Object-Relational)
Storage

Binary XML Storage

Unstructured (CLOB) Storage

Optimized
memory
management

+ XML operations can be optimized to
reduce memory requirements.

+ XML operations can be
optimized to reduce memory
requirements.

– XML operations on the document
require creating a DOM from the
document.

Validation
upon insert

XML data is partially validated when
it is inserted.

+ XML schema-based data is
fully validated when it is
inserted.

XML schema-based data is partially
validated when it is inserted.

Partitioning

+ Available.1

Partition based on virtual
columns.

XMLType columns can be
partitioned if the partitioning key is
a relational column.

Streams-based
replication

– Not available.

– Not available.

++ Available.

Compression

++ XML elements and attributes can
be compressed individually.

+ XML data that uses SecureFile – Not available.
LOB storage can be compressed.

1

Partitioning of ordered collection tables (OCTs) reflects the partitioning of the top-level XMLType tables. Partition maintenance
operations on the top-level tables are cascaded to the associated OCTs. See "Partitioning XMLType Tables and Columns Stored
Object-Relationally" on page 9-10.

When you insert XML schema-based data into binary
XMLType columns or tables, the data is fully validated against the XML
schema. Insertion fails if the data is invalid.

Note:

When XMLType is stored object-relationally, the XMLType instances contain hidden
columns that store information about the XML data that does not fit into the SQL
object model.

XML/SQL Duality
A key objective of Oracle XML DB is to provide XML/SQL duality. XML programmers
can leverage the power of the relational model when working with XML content and
SQL programmers can leverage the flexibility of XML when working with relational
content. This lets you use the most appropriate tools for a particular business problem.
XML/SQL duality means that the same data can be exposed as rows in a table and
manipulated using SQL or exposed as nodes in an XML document and manipulated
using techniques such as DOM and XSL transformation. Access and processing
techniques are independent of the underlying storage format.
These features provide simple solutions to common business problems. For example:
■

■

■

You can use Oracle XML DB SQL functions to generate XML data directly from a
SQL query. You can then transform the XML data into other formats, such as
HTML, using the database-resident XSLT processor.
You can access XML content without converting between different data formats,
using SQL queries, on-line analytical processing (OLAP), and
business-intelligence/data warehousing operations.
You can perform text, spatial data, and multimedia operations on XML content.

Introduction to Oracle XML DB 1-19

Oracle XML DB Features

SQL/XML Standard Functions
Oracle XML DB provides the SQL functions that are defined in the SQL/XML
standard. SQL/XML functions fall into two groups:
■

■

Functions that you can use to generate XML data from the result of a SQL query. In
this book, these are called SQL/XML publishing functions. They are also
sometimes called SQL/XML generation functions.
Functions that you can use to query and access XML content as part of normal SQL
operations. In this book, these are called SQL/XML query and access functions.

Using SQL/XML functions you can address XML content in any part of a SQL
statement. These functions use XQuery or XPath expressions to traverse the XML
structure and identify the nodes on which to operate. The ability to embed XQuery
and XPath expressions in SQL statements greatly simplifies XML access.
See Also:
■

■

■

■

■

Oracle Database SQL Language Reference for information about
Oracle support for the SQL/XML standard
Chapter 4, "XMLType Operations" and Chapter 5, "Using XQuery
with Oracle XML DB" for detailed descriptions of the SQL/XML
standard functions for querying XML data
Generating XML using SQL Functions on page 18-2 for
information about SQL/XML standard functions for generating
XML data
Chapter 3, "Using Oracle XML DB" for additional examples that
use SQL/XML standard functions
"Standards Supported by Oracle XML DB" on page 1-27

Automatic Rewriting of XQuery and XPath Expressions
SQL/XML functions and XMLType methods use XQuery or XPath expressions to
search collections of XML documents and to access a subset of the nodes contained
within an XML document. In many cases, Oracle XML DB is able to automatically
rewrite such expressions to code that executes directly against the underlying database
objects.

How XPath Expressions Are Evaluated by Oracle XML DB
Oracle XML DB provides the following ways of evaluating XPath expressions that
operate on XMLType columns and tables, depending on the XML storage method
used:
■

■

Structured storage – Oracle XML DB attempts to translate the XPath expression in
a SQL/XML function into an equivalent SQL query. The SQL query references the
object-relational data structures that underpin a schema-based XMLType. This
process is referred to as XPath rewrite. It can occur when performing queries and
UPDATE operations. In addition, B-tree indexes on the underlying object-relational
tables can be used to evaluate XPath expressions for structured storage.
Unstructured storage – XMLIndex indexes can be used to evaluate XPath
expressions for unstructured storage. Use XMLIndex by preference.
–

If an XMLIndex index can be used, then it is used instead of functional
evaluation.

1-20 Oracle XML DB Developer's Guide

Oracle XML DB Features

–

■

In the absence of such an index, Oracle XML DB evaluates the XPath
expression using functional evaluation. Functional evaluation builds a DOM
tree for each XML document, and then resolves the XPath programmatically
using the methods provided by the DOM API. If the operation involves
updating the DOM tree, the entire XML document must be written back to
disk when the operation is completed.

Binary XML storage – Oracle XML DB can evaluate XPath expressions in different
ways: using XMLIndex and using single-pass streaming. Single-pass streaming
means evaluating a set of XPath expressions in a single scan of binary XML data.
During query compilation, the cost-based optimizer picks the fastest combination
of evaluation methods.
See Also: Table 1–3, " XMLType Storage Models: Relative
Advantages"

Rewriting SQL Code That Contains XQuery and XPath Expressions
For XML data that is stored object-relationally, Oracle XML DB can rewrite SQL
statements that contain XQuery and XPath expressions to purely relational SQL
statements, which are then processed in an optimal manner. In this way, Oracle
XML DB insulates the database optimizer from needing to understand the XQuery and
XPath languages and the XML data model. The database optimizer processes a
rewritten SQL statement the same way it processes other SQL statements. The general
term applied to this rewriting process is XPath rewrite.
The database optimizer can thus derive an execution plan based on conventional
relational algebra. This in turn means that Oracle XML DB can leverage all of the
features of the database, and ensure that SQL statements containing XQuery and
XPath expressions are executed in a highly performant and efficient manner. There is
little overhead with this rewriting, and Oracle XML DB executes XQuery-based and
XPath-based queries at near-relational speed, while preserving the XML abstraction.

When Can XPath Rewrite Occur?
XPath rewrite is possible when all of the following conditions are met:
■

■
■

■

An XMLType column or table uses structured storage techniques to provide the
underlying storage model.
An XMLType column or table is associated with a registered XML schema.
A SQL statement contains SQL/XML functions or XMLType methods that use
XPath expressions to refer to one or more nodes within a set of XML documents.
The nodes referenced by an XPath expression can be mapped, using the XML
schema, to attributes of the underlying SQL object model.

What is the XPath-Rewrite Process?
XPath rewrite performs the following tasks:
1.

Identify the set of XPath expressions included in the SQL statement.

2.

Translate each XPath expression into an object relational SQL expression that
references the tables, types, and attributes of the underlying SQL: 1999 object
model.

3.

Rewrite the original SQL statement into an equivalent object relational SQL
statement.

Introduction to Oracle XML DB 1-21

Oracle XML DB Benefits

4.

Pass the new SQL statement to the database optimizer for plan generation and
query execution.

In certain cases, XPath rewrite is not possible. This normally occurs when there is no
SQL equivalent of the XPath expression. In this situation, Oracle XML DB performs a
functional evaluation of the XPath expressions.
In general, functional evaluation of a SQL statement is more expensive than XPath
rewrite, particularly if the number of documents to be processed is large. The
advantage of functional evaluation is that it is always possible, regardless of whether
the XMLType data is stored using structured storage and regardless of the complexity
of the XPath expression.
Understanding the concept of XPath rewrite, and the conditions under which it can
take place, is a key step in developing Oracle XML DB applications that deliver the
required levels of scalability and performance.
See Also:

Chapter 8, "XPath Rewrite for Structured Storage"

Oracle XML DB Benefits
This section describes several benefits of using Oracle XML DB. Figure 1–6 presents an
overview.

1-22 Oracle XML DB Developer's Guide

Oracle XML DB Benefits

Figure 1–6 Oracle XML DB Benefits

Oracle
XML DB

Faster Storage and
Retrieval of Complex
XML Documents

Unifies Data
and Content

Enhanced native
database support for
XML
Stores and manages
structured, unstructured,
and semi-structured data

Higher performance
of XML operations
Higher scalability
of XML operations

Transparent XML and SQL
interoperability

Helps
Integrate
Applications

XMLType views
over local or remote
sources

Also Handles
non-XML Data
with XMLType
Views

Facilitates migrating of
legacy and non-XML to
XML data

Connectivity to other
databases, files, ...
Uniform SQL / XML
queries over data
integrated from
multiple sources

Exploits database features:

indexing, searching
updating, transaction processing
manages constraints
multiple data views
speeds up XML storage, retrieval
supports standards for storing,
modifying, retrieving data
Exploits XML features:

structure and storage independence
facilitates presentation and data display
facilitates B2B data exchange

Unifying Data and Content
Most application data and Web content is stored in a relational database, a file system,
or both. XML data is often used for data exchange, and it can be generated from a
relational database or a file system. As the volume of XML data exchanged grows, the
cost of regenerating this data grows, and these storage methods become less effective
at accommodating XML content.

Introduction to Oracle XML DB 1-23

Oracle XML DB Benefits

Figure 1–7 Unifying Data and Content: Some Common XML Architectures
Non-Native XML Processing

Separate Data and Content Servers

Applications

Applications

Application Server

Oracle XML DB

Applications

Oracle
Application
Server

Application Server

XML Processing and
Repository Layer

File
System

Multimedia and
Document Content

RDBMS

XML
Repository

RDBMS

Oracle
XML DB

Structured Data
and Metadata

Multimedia, Document
Content and XML,
Metadata

Structured Data

Multimedia and
Document Content,
Structured Data,
XML, Metadata

Organizations often manage their structured data and unstructured data differently:
■

■

Unstructured data, in tables, makes document access transparent and table access
complex.
Structured data, often in binary large objects (such as in BLOB instances), makes
access more complex and table access transparent.

With Oracle XML DB, you can store and manage data that is structured, unstructured,
and semi-structured using a standard data model and standard SQL and XML. You
can perform SQL operations on XML documents and XML operations on
object-relational (such as table) data.

Exploiting Database Capabilities
Oracle Database has the following key database capabilities for working with XML:
■

Indexing and search – Applications use queries such as "find all the product
definitions created between March and April 2002", a query that is typically
supported by a B-tree index on a date column. Oracle XML DB can enable efficient
structured searches on XML data, saving content-management vendors the need
to build proprietary query APIs to handle such queries.
See Also:

■

■

Chapter 4, "XMLType Operations"

■

Chapter 12, "Full-Text Search Over XML Data"

■

Chapter 18, "Generating XML Data from the Database"

Updates and transaction processing – Commercial relational databases use fast
updates of subparts of records, with minimal contention between users trying to

1-24 Oracle XML DB Developer's Guide

Oracle XML DB Benefits

update. As traditionally document-centric data participate in collaborative
environments through XML, this requirement becomes more important. File or
CLOB storage cannot provide the granular concurrency control that Oracle
XML DB does.
See Also:
■

Chapter 4, "XMLType Operations"

Managing relationships – Data with any structure typically has foreign-key
constraints. XML data stores generally lack this feature, so you must implement
any constraints in application code. Oracle XML DB enables you to constrain XML
data according to XML schema definitions, and hence achieve control over
relationships that structured data has always enjoyed.
See Also:
■
■

■

Chapter 7, "XML Schema Storage and Query: Basic"
The purchase-order examples in Chapter 4, "XMLType
Operations"

Multiple views of data – Most enterprise applications need to group data together
in different ways for different modules. This is why relational views are
necessary—to allow for these multiple ways to combine data. By allowing views
on XML, Oracle XML DB creates different logical abstractions on XML for, say,
consumption by different types of applications.
See Also:

■

Chapter 19, "XMLType Views"

Performance and scalability – Users expect data storage, retrieval, and query to be
fast. Loading a file or CLOB value, and parsing, are typically slower than relational
data access. Oracle XML DB dramatically speeds up XML storage and retrieval.
See Also:

■

■

Chapter 2, "Getting Started with Oracle XML DB"

■

Chapter 3, "Using Oracle XML DB"

Ease of development – Databases are foremost an application platform that
provides standard, easy ways to manipulate, transform, and modify individual
data elements. While typical XML parsers give standard read access to XML data
they do not provide an easy way to modify and store individual XML elements.
Oracle XML DB supports several standard ways to store, modify, and retrieve
data. These include XML Schema, XQuery, XPath, DOM, and Java.
See Also:
■
■

■

Chapter 15, "Java DOM API for XMLType"
Chapter 25, "Accessing the Repository using RESOURCE_
VIEW and PATH_VIEW"
Chapter 26, "Accessing the Repository using PL/SQL"

Exploiting XML Capabilities
If the drawbacks of XML file storage force you to break down XML into database
tables and columns, there are several XML advantages you have left:

Introduction to Oracle XML DB 1-25

Oracle XML DB Benefits

■

Structure independence: The open content model of XML cannot be captured
easily in the pure tables-and-columns world. XML schemas allow global element
declarations, not just scoped to a container. Hence you can find a particular data
item regardless of where in the XML document it moves to as your application
evolves.
See Also:

■

Chapter 7, "XML Schema Storage and Query: Basic"

Storage independence: When you use relational design, your client programs must
know where your data is stored, in what format, what table, and what the
relationships are among those tables. XMLType enables you to write applications
without that knowledge and lets database administrators map structured data to
physical table and column storage.
See Also:

■

■

Chapter 7, "XML Schema Storage and Query: Basic"

■

Chapter 21, "Accessing Oracle XML DB Repository Data"

Ease of presentation: XML is understood natively by Web browsers, many popular
desktop applications, and most Internet applications. Relational data is generally
not accessible directly from applications. Additional programming is required to
make relational data accessible to standard clients. Oracle XML DB stores data as
XML and makes it available as XML outside the database. No extra programming
is required to display database content.
See Also:

■

■

Chapter 11, "Transforming and Validating XMLType Data".

■

Chapter 18, "Generating XML Data from the Database".

■

Chapter 19, "XMLType Views".

Ease of interchange – XML is the language of choice in business-to-business (B2B)
data exchange. If you are forced to store XML in an arbitrary table structure, you
are using some kind of proprietary translation. Whenever you translate a
language, information is lost and interchange suffers. By natively understanding
XML and providing DOM fidelity in the storage/retrieval process, Oracle XML DB
enables a clean interchange.
See Also:
■

Chapter 11, "Transforming and Validating XMLType Data"

■

Chapter 19, "XMLType Views"

Efficient Storage and Retrieval of Complex XML Documents
Users today face a performance barrier when storing and retrieving complex, large, or
many XML documents. Oracle XML DB provides high performance and scalability for
XML operations. The major performance features are:
■

Native XMLType. See Chapter 4, "XMLType Operations".

■

A lazily evaluated virtual DOM. See Chapter 13, "PL/SQL APIs for XMLType".

■

XQuery, XPath, and XSLT support. This is described in several chapters, including
Chapter 4, "XMLType Operations", Chapter 11, "Transforming and Validating
XMLType Data", and Chapter 5, "Using XQuery with Oracle XML DB".

1-26 Oracle XML DB Developer's Guide

Standards Supported by Oracle XML DB

■

■

■

XML schema caching support. See Chapter 7, "XML Schema Storage and Query:
Basic".
Indexing, both full-text and XML. See Chapter 6, "Indexing XMLType Data" and
Chapter 12, "Full-Text Search Over XML Data".
A hierarchical index over Oracle XML DB Repository. See Chapter 21, "Accessing
Oracle XML DB Repository Data".

Use XMLType Views If Your Data Is Not XML
XMLType views provide a way for you wrap existing relational and object-relational
data in XML format. This is especially useful if, for example, your legacy data is not in
XML format but you must migrate it to XML format. Using XMLType views, you need
not alter your application code.
See Also:

Chapter 19, "XMLType Views"

To use XMLType views, you must first register an XML schema with annotations that
represent a bidirectional mapping between XML Schema data types and either SQL
data types or binary XML encoding types. You can then create an XMLType view
conforming to this mapping, by providing an underlying query that constructs
instances of the appropriate types.

Search XML Data using Oracle Text
Oracle Database enables special indexing on XML data, including Oracle Text indexes
for section searching, SQL functions to process XML data, aggregation of XML data,
and special optimization of queries involving XML data. Oracle SQL functions
hasPath and inPath are designed to optimize XML data searches where you can
search within XML text for substring matches.
See Also:
■

Chapter 12, "Full-Text Search Over XML Data"

■

"Oracle Text Indexes on XML Data" on page 6-46

■

Oracle Text Application Developer's Guide

■

Oracle Text Reference

Build Messaging Applications using Oracle Streams Advanced Queuing
Oracle Streams Advanced Queuing supports the use of:
■

XMLType as a message/payload type, including XML schema-based XMLType

■

Queuing or dequeuing of XMLType messages
See Also:
■

■

Oracle Streams Advanced Queuing User's Guide for information
about using XMLType with Oracle Streams Advanced Queuing
Chapter 37, "Exchanging XML Data using Oracle Streams AQ"

Standards Supported by Oracle XML DB
Oracle XML DB supports all major XML, SQL, Java, and Internet standards:

Introduction to Oracle XML DB 1-27

Standards Supported by Oracle XML DB

■

■

■
■

■

■

■

■

■

■

■

W3C XML Schema 1.0 Recommendation. You can register XML schemas, validate
stored XML content against XML schemas, or constrain XML stored in the server
to XML schemas.
W3C XQuery 1.0 Recommendation and W3C XPath 2.0 Recommendation. You can
search or traverse XML stored inside the database using XQuery and XPath, either
from HTTP(S) requests or from SQL.
SQL/XML.
Java Database Connectivity (JDBC) API. JDBC access to XML is available for Java
programmers.
W3C XSL 1.0 Recommendation. You can transform XML documents at the server
using XSLT.
W3C DOM Recommendation Levels 1.0 and 2.0 Core. You can retrieve XML stored
in the server as an XML DOM, for dynamic access.
Protocol support. You can store or retrieve XML data from Oracle XML DB using
Oracle Net or standard protocols such as HTTP(S), FTP, and IETF WebDAV.
Java Servlet version 2.2, (except: the servlet WAR file, web.xml, is not supported
in its entirety; only one ServletContext; one web-app are currently supported;
and stateful servlets are not supported).
Web services: SOAP 1.1. You can access XML stored in the server from SOAP
requests. You can build, publish, or find Web Services using Oracle XML DB and
Oracle9iAS, using WSDL and UDDI. You can use Oracle Streams Advanced
Queuing IDAP, the SOAP specification for queuing operations, on XML stored in
Oracle Database.
W3C XML Linking Language (Xlink) 1.0 Recommendation. You can define various
types of links between XML documents.
W3C XML Pointer Language (XPointer) Recommendation and XPointer
Framework. You can include the content of multiple XML documents or fragments
in a single infoset.
See Also:
■

■

■

■

■

■

"SQL/XML Standard Functions" on page 1-20 for more
information about the SQL/XML functions
Oracle Database SQL Language Reference for information about
Oracle support for the SQL/XML standard
Chapter 23, "Using XLink and XInclude with Oracle XML DB" for
more information about XLink and XPointer support
Chapter 28, "Accessing the Repository using Protocols" for more
information about protocol support
Chapter 32, "Writing Oracle XML DB Applications in Java" for
information about using the Java servlet
Chapter 37, "Exchanging XML Data using Oracle Streams AQ"
and Oracle Streams Advanced Queuing User's Guide for information
about using SOAP

1-28 Oracle XML DB Developer's Guide

Further Oracle XML DB Case Studies and Demonstrations

Oracle XML DB Technical Support
Besides your regular channels of support through your customer representative or
consultant, technical support for Oracle Database XML-enabled technologies is
available free through the Discussion Forums section of Oracle Technology Network
(OTN):
http://forums.oracle.com/forums/category.jspa?categoryID=51

Oracle XML DB Examples Used in This Manual
This manual contains examples that illustrate the use of Oracle XML DB and
XMLType. The examples are based on various database schemas, sample XML
documents, and sample XML schemas.
See Also: Appendix A, "Oracle-Supplied XML Schemas and
Examples"

Further Oracle XML DB Case Studies and Demonstrations
Visit OTN to view Oracle XML DB examples, white papers, case studies, and
demonstrations:
http://www.oracle.com/technetwork/database-features/xmldb/overvi
ew/index.html
Comprehensive XML classes on how to use Oracle XML DB are also available. See the
Oracle University link on OTN.
Several detailed Oracle XML DB case studies are available on OTN and include the
following:
■

■

■

■

■

Oracle XML DB Downloadable Demonstration. This detailed demonstration
illustrates how to use many Oracle XML DB features. Parts of this demonstration
are also included in Chapter 3, "Using Oracle XML DB".
SAX Loader Application. This demonstrates an efficient way to break up large files
containing multiple XML documents outside the database and insert them into the
database as a set of separate documents. This is provided as a standalone and a
Web-based application.
Oracle XML DB Utilities package. This highlights the subprograms provided with
the XDB_Utilities package. These subprograms operate on BFILE values,
CLOB values, DOM, and Oracle XML DB Resource APIs. With this package, you
can perform basic Oracle XML DB foldering operations, read and load XML files
into a database, and perform basic DOM operations through PL/SQL.
Card Payment Gateway Application. This application uses Oracle XML DB to
store all your data in XML format and enables access to the resulting XML data
using SQL. It illustrates how a credit card company can store its account and
transaction data in the database and also maintain XML fidelity.
Survey Application. This application determines what members want from Oracle
products. OTN posts the online surveys and studies the responses. This Oracle
XML DB application demonstrates how a company can create dynamic, interactive
HTML forms, deploy them to the Internet, store the responses as XML, and
analyze them using the XML enabled Oracle Database.

Introduction to Oracle XML DB 1-29

Further Oracle XML DB Case Studies and Demonstrations

1-30 Oracle XML DB Developer's Guide

2
Getting Started with Oracle XML DB
This chapter provides some preliminary design criteria for consideration when
planning your Oracle XML DB solution.
This chapter contains these topics:
■

Oracle XML DB Installation

■

Oracle XML DB Use Cases

■

Application Design Considerations for Oracle XML DB

■

Oracle XML DB Performance

Oracle XML DB Installation
Oracle XML DB is installed automatically in the following situations:
■

■

If Database Configuration Assistant (DBCA) is used to build Oracle Database
using the general-purpose template
If you use SQL script catqm to install Oracle Database

You can determine whether or not Oracle XML DB is already installed. If it is installed,
then the following are true:
■

Database schema (user account) XDB exists. To check that, run this query:
SELECT * FROM ALL_USERS;

■

View RESOURCE_VIEW exists. To check that, use this command:
DESCRIBE RESOURCE_VIEW

See Also:
■

■

Chapter 34, "Administering Oracle XML DB" for information
about installing and uninstalling Oracle XML DB manually
Oracle Database 2 Day + Security Guide for information about
database schema XDB

Oracle XML DB Use Cases
Oracle XML DB is suited for any application where some or all of the data processed
by the application is represented using XML. Oracle XML DB provides for
high-performance database ingestion, storage, processing and retrieval of XML data. It
also lets you quickly and easily generate XML from existing relational data.
Applications for which Oracle XML DB is particularly suited include the following:
Getting Started with Oracle XML DB

2-1

Application Design Considerations for Oracle XML DB

■

Business-to-business (B2B) and application-to-application (A2A) integration

■

Internet

■

Content-management

■

Messaging

■

Web Services

A typical Oracle XML DB application has one or more of the following characteristics:
■

Large numbers of XML documents must be ingested or generated

■

Large XML documents must be processed or generated

■

High-performance searching is needed, both within a document and across large
collections of documents

■

High levels of security are needed

■

Fine-grained security is needed

■

■

■

Data processing must use XML documents, and data must be stored in relational
tables
Programming must support open standards such as SQL, XML, XQuery, XPath,
and XSL
Information must be accessed using standard Internet protocols such as FTP,
HTTP(S)/WebDAV, and Java Database Connectivity (JDBC)

■

XML data must be queried from SQL

■

Analytic capabilities must be applied to XML data

■

XML documents must be validated against an XML schema

Oracle XML DB lets you fine-tune how XML documents are stored and processed in
Oracle Database. Depending on the nature of the application, XML storage must have
at least one of the following features
■

High performance ingestion and retrieval of XML documents

■

High performance indexing and searching of XML documents

■

Ability to update sections of an XML document

■

Management of structured or unstructured XML documents

Application Design Considerations for Oracle XML DB
This section mentions some preliminary design criteria that you can consider when
planning your Oracle XML DB application.

Structure of Your Data
Is your data be highly structured (mostly XML), semi-structured, or mostly
unstructured? If highly structured, are your tables XML schema-based or
non-schema-based?
If your XML data is not XML schema-based, then, regardless of how structured it is,
you can store it in an XMLType table or view as binary XML or as a CLOB instance, or
you can store it as a file in an Oracle XML DB Repository folder.

2-2 Oracle XML DB Developer's Guide

Application Design Considerations for Oracle XML DB

If your XML data is XML schema-based then you can use unstructured, structured
(object-relational), or binary XML storage for its structured parts. For the unstructured
parts, you have the same options as for data that is not XML schema-based.
See Also:

Chapter 3, "Using Oracle XML DB"

Oracle XML DB Repository Access
This section pertains to data that is stored as resources in Oracle XML DB Repository.
How do other applications and users need to access your XML and other data? How
secure must the access be? Do you need versioning?
There are two main repository access methods:
■

■

Navigation-based access or path-based access. This is suitable for both
content/document and data oriented applications. Oracle XML DB provides the
following languages and access APIs:
–

SQL access through resource and path views. See Chapter 25, "Accessing the
Repository using RESOURCE_VIEW and PATH_VIEW".

–

PL/SQL access through DBMS_XDB. See Chapter 26, "Accessing the Repository
using PL/SQL".

–

Protocol-based access using HTTP(S)/WebDAV or FTP, most suited to
content-oriented applications. See Chapter 28, "Accessing the Repository using
Protocols".

Query-based access. This can be most suited to data oriented applications. Oracle
XML DB provides access using SQL queries through the following APIs:
–

Java access (through JDBC). See Java DOM API for XMLType.

–

PL/SQL access. See Chapter 13, "PL/SQL APIs for XMLType".

These options for accessing repository data are also discussed in Chapter 21,
"Accessing Oracle XML DB Repository Data".
You can also consider the following access criteria:
■
■

■

What levels of security do you need? See Chapter 27, "Repository Access Control".
What kind of indexing best suits your application? Do you need to use Oracle Text
indexing and querying? See Chapter 4, "XMLType Operations", Chapter 6,
"Indexing XMLType Data", and Chapter 12, "Full-Text Search Over XML Data".
Do you need to version the data? If yes, see Chapter 24, "Managing Resource
Versions".

Application Language
In which languages do you program your application?
You can program your Oracle XML DB applications in the following languages:
■

Java (JDBC, Java Servlets)
See Also:

■

■

Chapter 15, "Java DOM API for XMLType"

■

Chapter 32, "Writing Oracle XML DB Applications in Java"

PL/SQL
Getting Started with Oracle XML DB

2-3

Application Design Considerations for Oracle XML DB

See Also:
■

Chapter 13, "PL/SQL APIs for XMLType"

■

Chapter 26, "Accessing the Repository using PL/SQL"

■

"APIs for XML" on page 1-4

Processing
Do you need to generate XML data? See Chapter 18, "Generating XML Data from the
Database".
How often are XML documents accessed, updated, and manipulated? Do you need to
update fragments or whole documents?
Do you need to transform XML data to HTML, WML, or other languages? If so, how
does your application do this? See Chapter 11, "Transforming and Validating XMLType
Data".
Must your application be primarily database-resident or must it work in both the
database and middle tier?
Is your application data-centric, document-centric (content-centric), or both?
The following processing options are available and should be considered when
designing your Oracle XML DB application:
■

■

■

■

XSLT. Do you need to transform the XML data to HTML, WML, or other
languages, and, if so, how does your application transform the XML data? While
storing XML documents in Oracle XML DB, you can optionally ensure that their
structure complies with (validates against) specific XML schemas. See Chapter 11,
"Transforming and Validating XMLType Data".
DOM fidelity, document fidelity. Use unstructured storage to preserve document
fidelity. Use binary XML or structured storage for XML schema-based data to
preserve DOM fidelity. See Chapter 13, "PL/SQL APIs for XMLType" and "DOM
Fidelity" on page 7-16.
XPath searching. You can use XPath syntax embedded in a SQL statement or as
part of an HTTP(S) request to query XML content in the database. See Chapter 4,
"XMLType Operations", Chapter 12, "Full-Text Search Over XML Data",
Chapter 21, "Accessing Oracle XML DB Repository Data", and Chapter 25,
"Accessing the Repository using RESOURCE_VIEW and PATH_VIEW".
XML Generation and XMLType views. Do you need to generate or regenerate XML
data? If yes, see Chapter 18, "Generating XML Data from the Database".

How often are XML documents accessed, updated, and manipulated? See Chapter 4,
"XMLType Operations" and Chapter 25, "Accessing the Repository using RESOURCE_
VIEW and PATH_VIEW".
Do you need to update fragments or whole documents? You can use XPath
expressions to specify individual elements and attributes of your document during
updates, without rewriting the entire document. This is more efficient, especially for
large XML documents. Chapter 7, "XML Schema Storage and Query: Basic".
Is your application data-centric, document- and content-centric, or integrated (is both
data- and document-centric)? See Chapter 3, "Using Oracle XML DB".

2-4 Oracle XML DB Developer's Guide

Application Design Considerations for Oracle XML DB

Messaging
Does your application exchange XML data with other applications across gateways?
Do you need Oracle Streams Advanced Queuing (AQ) or SOAP compliance? See
Chapter 37, "Exchanging XML Data using Oracle Streams AQ".
Advanced Queuing (AQ) supports XML and XMLType applications. You can create
queues with payloads that contain XMLType attributes. These can be used for
transmitting and storing messages that contain XML documents. By defining Oracle
Database objects with XMLType attributes, you can do the following:
■

■

■

■

Store more than one type of XML document in the same queue. The documents
are stored internally as CLOB values.
Selectively dequeue messages with XMLType attributes using an XPath or XQuery
expression.
Define rule-based subscribers that query message content using an XPath or
XQuery expression.
Define transformations to convert Oracle Database objects to XMLType.
See Also:
■

Chapter 37, "Exchanging XML Data using Oracle Streams AQ"

■

Oracle Streams Advanced Queuing User's Guide

Storage
How and where do you store your relational data, XML data, XML schemas, and so
on?
The choices you make for data structure, access, language,
and processing are typically interdependent, but they are not
dependent on the storage model you choose.

Note:

Figure 2–1 shows the Oracle XML DB storage options for XMLType tables and views.

Getting Started with Oracle XML DB

2-5

Oracle XML DB Performance

Figure 2–1 Oracle XML DB Storage Options for XML Data
Oracle XML DB Data
Storage Options
Your Storage Option Affects Performance
and Data Fidelity
XMLType
Tables

XMLType
Views

If you have existing
relational data use
XMLType Views

Can define the
views using:
Binary
XML
Storage

Unstructured
Storage

Structured
Storage

Hybrid
Storage

SQL / XML
Operators

Object
Types

Relational
Tables
Object
Tables

Object
Views

Object
Constructors
Relational
Tables

If you have existing relational data, you can access it as XML data by creating
XMLType views over it. You can use the following to define the XMLType views:
■

■

SQL/XML functions. See Chapter 18, "Generating XML Data from the Database"
and Chapter 5, "Using XQuery with Oracle XML DB".
Object types: object tables, object constructors, and object views.

Regardless of which storage options you choose for your application, Oracle XML DB
provides the same functionality. Though the storage model you use can affect your
application performance and XML data fidelity, it is totally independent of all of the
following:
■
■

■

How, and how often, you query or update your data.
How you access your data. This is determined only by your application processing
requirements.
What language(s) your application uses. This is determined only by your
application processing requirements.
See Also:
■

"XMLType Storage Models" on page 1-14

■

"DOM Fidelity" on page 7-16

Oracle XML DB Performance
One objection to using XML to represent data is that it generates higher overhead than
other representations. Oracle XML DB incorporates several features specifically
designed to address this issue by significantly improving the performance of XML
processing. These are described in the following sections:
■

XML Storage Requirements

2-6 Oracle XML DB Developer's Guide

Oracle XML DB Performance

■

XML Memory Management

■

XML Parsing Optimizations

■

Node-Searching Optimizations

■

XML Schema Optimizations

■

Load Balancing Through Cached XML Schema

■

Reduced Bottlenecks From Code That Is Not Native

■

Reduced Java Type Conversion Bottlenecks

XML Storage Requirements
Data represented in XML and stored in a text file averages three times the size of the
same data in a Java object or in relational tables. There are two main reasons for this:
■

■

Tag names (metadata describing the data) and white space (formatting characters)
take up a significant amount of space in the document, particularly for highly
structured, data-centric XML.
All data in an XML file is represented in human readable (string) format.

The string representation of a numeric value needs about twice as many bytes as the
native (binary) representation. When XML documents are stored in Oracle XML DB
using structured or binary XML storage, the storage process discards all tags and
white space in the document.
The amount of space saved by this optimization depends on the ratio of tag names to
data, and the number of collections in the document. For highly-structured,
data-centric XML data, the savings can be significant. When a document is printed, or
when node-based operations such as XPath evaluation take place, Oracle XML DB
uses the information contained in the associated XML schema to dynamically
reconstruct any necessary tag information.

XML Memory Management
Document Object Model (DOM) is the dominant programming model for XML
documents. DOM APIs are easy to use but the DOM Tree that underpins them is
expensive to generate, in terms of memory. A typical DOM implementation maintains
approximately 80 to 120 bytes of system overhead for each node in the DOM tree. For
highly structured data, the DOM tree can require 10 to 20 times more memory than the
document on which it is based.
A conventional DOM implementation requires the entire contents of an XML
document to be loaded into the DOM tree before any operations can take place. If an
application only needs to process a small percentage of the nodes in the document, this
is extremely inefficient in terms of memory and processing overhead. The alternative
Simple API for XML (SAX) approach reduces the amount of memory required to
process an XML document, but its disadvantage is that it only allows linear processing
of nodes in the XML document.
See Also:
■

http://www.w3.org/DOM/ for information about DOM

■

http://www.saxproject.org/ for information about SAX

Getting Started with Oracle XML DB

2-7

Oracle XML DB Performance

Use of XOBs Reduces Memory Overhead for XML Schema-Based Documents
Oracle XML DB reduces memory overhead associated with DOM programming by
managing XML schema-based XML documents using an internal structure in dynamic
memory called an XML Object (XOB). A XOB is much smaller than the equivalent
DOM since it does not duplicate information like tag names and node types, that can
easily be obtained from the associated XML schema. Oracle XML DB automatically
uses a XOB whenever an application works with the contents of a schema-based
XMLType. The use of the XOB is transparent to you. It is hidden behind the XMLType
data type and the C, PL/SQL, and Java APIs.

XOB Uses a Lazily-Loaded Virtual DOM
The XOB can also reduce the amount of memory required to work with an XML
document using the Lazily-Loaded Virtual DOM feature. This lets Oracle XML DB
defer loading the dynamic memory representation of nodes that are part of
sub-elements or collection until code attempts to operate on a node in that object.
Consequently, if an application only operates on a few nodes in a document, only
those nodes and their immediate siblings are loaded into memory.
The XOB can only used when an XML document is based on an XML schema. If the
contents of the XML document are not based on an XML schema, a traditional DOM is
used instead of the XOB.

XML Parsing Optimizations
To populate a DOM tree the application must parse the XML document. The process of
creating a DOM tree from an XML file is very CPU- intensive. In a typical DOM-based
application, where the XML documents are stored as text, every document has to be
parsed and loaded into the DOM tree before the application can work with it. If the
contents of the DOM tree are updated the entire tree must be serialized back into a text
format and written out to disk.
Oracle XML DB eliminates the need to parse documents over and over again. No
parsing is needed when an XML document is loaded from disk into memory, if the
document is stored as structured or binary XML storage. Oracle XML DB maps
directly between the format on disk and the format in dynamic memory using
information derived from the associated XML schema. When changes are made to
XML schema-based data, Oracle XML DB is able to write just the updated data back to
disk. When XML data is not based on an XML schema, a traditional DOM is used
instead.

Node-Searching Optimizations
Most DOM implementations use string comparisons when searching for a particular
node in the DOM tree. Even a simple search of a DOM tree can require hundreds or
thousands of instruction cycles. Searching for a node in a XOB is much more efficient
than searching for a node in a DOM. A XOB is based on a computed offset model,
similar to a C/C++ object, and uses dynamic hashtables rather than string
comparisons to perform node searches.

XML Schema Optimizations
Making use of the powerful features associated with XML schema in a conventional
XML application can generate significant amounts of additional overhead. For
example, before an XML document can be validated against an XML schema, the
schema itself must be located, parsed, and validated.

2-8 Oracle XML DB Developer's Guide

Oracle XML DB Performance

Oracle XML DB minimizes the overhead associated with using XML schema. When an
XML schema is registered with the database, it is loaded in the Oracle XML DB schema
cache, together with all of the metadata required to map between the textual, XOB and
on- disk representations of the data. After the XML schema has been registered with
the database no additional parsing or validation of the XML schema is required before
it can be used. The schema cache is shared by all users of the database. Whenever an
Oracle XML DB operation requires information contained in the XML schema, it can
access the required information directly from the cache.

Load Balancing Through Cached XML Schema
Some operations, such as performing a full schema validation, or serializing an XML
document back into text form, can still require significant memory and CPU resources.
Oracle XML DB let these operations be off-loaded to the client or middle tier processor.
Both Oracle Call Interface (OCI) interface and the OCI driver for JDBC allow the XOB
to be managed by the client.
The cached representation of the XML schema can also be downloaded to the client.
This lets operations such as XML printing, and XML schema validation be performed
using client or middle tier resources, rather than server resources.

Reduced Bottlenecks From Code That Is Not Native
Another bottleneck for XML-based Java applications happens when parsing an XML
file. Even natively compiled or JIT compiled Java performs XML parsing operations
twice as slowly compared to using native C language. One of the major performance
bottlenecks in implementing XML applications is the cost of transforming data in an
XML document between text, Java, and native server representations. The cost of
performing these transformations is proportional to the size and complexity of the
XML file and becomes severe even in moderately sized files.
Oracle XML DB addresses these issues by implementing all of the Java and PL/SQL
interfaces as thin facades over a native implementation in the C language. Java, C,
PL/SQL, and SQL all use the same underlying implementation. This provides for
language-neutral XML support and higher performance XML parsing and DOM
processing.

Reduced Java Type Conversion Bottlenecks
One of the biggest bottlenecks when using Java and XML is with type conversions.
Internally Java uses UCS-2 to represent character data. Most XML files and databases
do not contain UCS-2 encoded data. All data contained in an XML file must be
converted from 8-Bit or UTF-8 encoding to UCS-2 encoding before it can be
manipulated in a Java program.
Oracle XML DB addresses these problems with lazy type conversions. With lazy type
conversions, the content of a node is not converted into the format required by Java
until the application attempts to access the contents of the node. Data remains in the
internal representation till the last moment. Avoiding unnecessary type conversions
can result in significant performance improvements when an application only needs to
access a few nodes in an XML document.
Consider a JSP that loads a name from the Oracle Database and prints it out in the
generated HTML output. Typical JSP implementations read the name from the
database (that probably contains data in the ASCII or ISO8859 character sets), convert
the data to UCS-2, and return it to Java as a string. The JSP would not look at the string
content, but only print it out after printing the enclosing HTML, probably converting

Getting Started with Oracle XML DB

2-9

Oracle XML DB Performance

back to the same ASCII or ISO8859 for the client browser. Oracle XML DB provides a
write interface on XMLType so that any element can write itself directly to a stream
(such as a ServletOutputStream) without conversion through Java character sets.
Figure 2–2 shows the Oracle XML DB Application Program Interface (API) stack.
Figure 2–2 Oracle XML DB Application Program Interface (API) Stack
OCI-Based Application
C
XMLType
and DOM

Server-Based Application

Java
XMLType
and DOM

Java
XMLType
and DOM

PL/SQL
XMLType
and DOM

In Memory
Format
Schema-Based
XML
(XOB)

Non-Schema-Based
XML
(DOM)

On Disk
Format
XML
Schema
Cache

Structured
Storage

2-10 Oracle XML DB Developer's Guide

Binary
XML
Storage

Unstructured
Storage

3
Using Oracle XML DB
This chapter is an overview of how to use Oracle XML DB. The examples presented
here illustrate techniques for accessing and managing XML content in purchase-order
documents. Purchase orders are highly structured documents, but you can use the
techniques shown here to also work with XML documents that have little structure.
This chapter contains these topics:
■

Storing XML Data as XMLType

■

Creating XMLType Tables and Columns

■

Partitioning or Constraining Binary XML Data using Virtual Columns

■

Loading XML Content into Oracle XML DB

■

Character Sets of XML Documents

■

Overview of the W3C XML Schema Recommendation

■

Using XML Schema with Oracle XML DB

■

Identifying XML Schema Instance Documents

■

Enforcing XML Data Integrity using the Database

■

DML Operations on XML Content using Oracle XML DB

■

Querying XML Content Stored in Oracle XML DB

■

Accessing XML Data in Oracle XML DB using Relational Views

■

Updating XML Content Stored in Oracle XML DB

■

Namespace Support in Oracle XML DB

■

How Oracle XML DB Processes XMLType Methods and SQL Functions

■

Generating XML Data from Relational Data

■

XSL Transformation and Oracle XML DB

■

Using Oracle XML DB Repository

■

Viewing Relational Data as XML From a Browser

■

XSL Transformation using DBUri Servlet

Storing XML Data as XMLType
Before the introduction of Oracle XML DB, there were two ways to store XML content
in Oracle Database:

Using Oracle XML DB

3-1

Storing XML Data as XMLType

■

■

Use Oracle XML Developer's Kit (XDK) to parse the XML document outside
Oracle Database, and store the extracted XML data as rows in one or more tables
in the database.
Store the XML document in Oracle Database using a Character Large Object
(CLOB), Binary Large Object (BLOB), Binary File (BFILE), or VARCHAR column.

In both cases, Oracle Database is unaware that it is managing XML content.
Oracle XML DB and the XMLType abstract data type make Oracle Database
XML-aware. Storing XML data as an XMLType column or table lets the database
perform XML-specific operations on the content. This includes XML validation and
optimization. XMLType storage allows highly efficient processing of XML content in
the database.

What is XMLType?
XMLType is an abstract data type for native handling of XML data in the database.
■

XMLType has built-in methods to create, extract, and index database XML data.

■

XMLType provides SQL access to XML data.

■

XMLType functionality is also available through a set of Application Program
Interfaces (APIs) provided in PL/SQL and Java. XMLType can be used in PL/SQL
stored procedures for parameters, return values, and variables.

Using XMLType, SQL developers can leverage the power of the relational database
while working in the context of XML. XML developers can leverage the power of XML
standards while working in the context of a relational database.
XMLType can be used as the data type of columns in tables and views. XMLType
variables can be used in PL/SQL stored procedures as parameters and return values.
You can also use XMLType in SQL, PL/SQL, C, Java (through JDBC), and Oracle Data
Provider for .NET (ODP.NET).
The XMLType API provides several useful methods that operate on XML content. For
example, method extract() extracts one or more nodes from an XMLType instance.
Oracle XML DB functionality is based on the Oracle XML Developer's Kit C
implementations of the relevant XML standards such as XML Parser, XML DOM, and
XML Schema Validator.
See Also:
■
■

"XMLType Data Type" on page 1-12
"XMLType Storage Models" on page 1-14 for the available
XMLType storage options and their relative advantages

Benefits of XMLType Data Type and API
The XMLType data type and application programming interface (API) enable SQL
operations on XML content and XML operations on SQL content:
■

■

Versatile API – XMLType has a versatile API for application development that
includes built-in functions, indexing, and navigation support.
XMLType and SQL – You can use XMLType in SQL statements, combined with
other data types. For example, you can query XMLType columns and join the
result of the extraction with a relational column. Oracle Database determines an
optimal way to run such queries.

3-2 Oracle XML DB Developer's Guide

Partitioning or Constraining Binary XML Data using Virtual Columns

■

Indexing – You can created several kinds of indexes to improve the performance of
queries on XML data.
–

For structured storage of XMLType data, you can create B-tree indexes and
function-based indexes on the object-relational tables that underlie XMLType
tables and columns. Create function-based indexes only on scalar data, that is,
columns that represent singleton elements or attributes.

–

For unstructured and binary XML storage of XMLType data, you can create an
XMLIndex index, which specifically targets the XML structure of a document.

–

You can index the textual content of XML data with an Oracle Text CONTEXT
index, for use in full-text search. This applies to all XMLType storage models.

Creating XMLType Tables and Columns
XMLType is an abstract data type, so it is straightforward to create an XMLType table
or column. The basic CREATE TABLE statement, specifying no storage options and no
XML schema, stores XMLType data as binary XML.1
Example 3–1 creates an XMLType column, and Example 3–2 creates an XMLType table.
Example 3–1 Creating a Table with an XMLType Column
CREATE TABLE mytable1 (key_column VARCHAR2(10) PRIMARY KEY, xml_column XMLType);
Example 3–2 Creating a Table of XMLType
CREATE TABLE mytable2 OF XMLType;

See Also: "Creating XMLType Tables and Columns Based on XML
Schemas" on page 7-27

To create an XMLType table in a different database schema
from your own, you must have not only privilege CREATE ANY
TABLE but also privilege CREATE ANY INDEX. This is because a
unique index is created on column OBJECT_ID when you create the
table. Column OBJECT_ID stores a system-generated object identifier.

Note:

Partitioning or Constraining Binary XML Data using Virtual Columns
XML data has its own structure, which, except for object-relational storage of
XMLType, is not reflected directly in database data structure. That is, individual XML
elements and attributes are not mapped to individual database columns or tables.
Therefore, to constrain or partition XML data according to the values of individual
elements or attributes, the standard approach for relational data does not apply.
Instead, you must create virtual columns that represent the XML data of interest, and
then use those virtual columns to define the constraints or partitions that you need.
This approach applies only to XML data that is stored as binary XML. For XML data
that uses unstructured storage, the database has no knowledge of the XML
structure—the data is treated as flat text, but for binary XML storage that structure is

1

The XMLType storage model for XML schema-based data is whatever was specified during
registration of the referenced XML schema. If no storage model was specified during
registration, then binary XML storage is used.

Using Oracle XML DB

3-3

Partitioning or Constraining Binary XML Data using Virtual Columns

known. You can exploit this structural knowledge to create virtual columns, which the
database can then use with constraints or partitions.
The technique is as follows:
1.

Define virtual columns that correspond to the XML data that you are interested in.

2.

Use those columns to partition or constrain the XMLType data as a whole.

You create virtual columns on XMLType data as you would create virtual columns
using any other type of data, but using a slightly different syntax. In particular, you
cannot specify any constraints in association with the column definition.
Because XMLType is an abstract data type, if you create virtual columns on an
XMLType table then those columns are hidden. They do not show up in DESCRIBE
statements, for example. This hiding enables tools that use operations such as
DESCRIBE to function normally and not be misled by the virtual columns.
Note:
■

■
■

Partitioning of binary XML tables is supported starting with 11g
Release 2 (11.2). It is supported only if the database compatibility
(parameter compatible in file init.ora) is 11.2 or higher.
Range, hash, and list partitioning are supported.
You can partition an XMLType table using a virtual column. You
cannot partition a relational table that has an XMLType column,
using that column to define virtual columns of XML data.

You create a virtual column based on an XML element or attribute by defining it in
terms of a SQL expression that involves that element or attribute. The column is thus
function-based. You use SQL/XML functions XMLCast and XMLQuery to do this, as
shown in Example 3–3. The XQuery expression argument to function XMLQuery must
be a simple XPath expression that uses only the child and attribute axes.
Example 3–3 Partitioning a Binary XML Table using Virtual Columns
CREATE TABLE po_binaryxml OF XMLType
XMLTYPE STORE AS BINARY XML
VIRTUAL COLUMNS
(DATE_COL AS (XMLCast(XMLQuery('/PurchaseOrder/@orderDate'
PASSING OBJECT_VALUE RETURNING CONTENT)
AS DATE)))
PARTITION BY RANGE (DATE_COL)
(PARTITION orders2001 VALUES LESS THAN (to_date('01-JAN-2002')),
PARTITION orders2002 VALUES LESS THAN (MAXVALUE));

Example 3–3 partitions an XMLType table using a virtual column, DATE_COL, which
targets the orderDate element in a purchase-order document.
To use a virtual column for partitioning, its data type must be constant. In the case
where the XMLType data in the column or table is mixed, some documents being
encoded using an XML schema and others being encoded without using any schema,
you must cast the functional expression, to ensure that the same data type is used for
all rows in the virtual column.

3-4 Oracle XML DB Developer's Guide

Loading XML Content into Oracle XML DB

For best performance, choose, as the partitioning key, an XPath
expression whose target occurs within 32 K bytes of the beginning of
the XML document.

Note:

You define constraints on binary XML data similarly. See Example 3–20 on page 3-35.
See Also:
■
■

■

"XMLIndex Partitioning and Parallelism" on page 6-34
"Enforcing Referential Integrity using SQL Constraints" on
page 3-34
Oracle Database SQL Language Reference for information about
creating tables with virtual columns

Loading XML Content into Oracle XML DB
You can load XML content into Oracle XML DB using these techniques:
■

■

Table-based loading:
■

Loading XML Content using SQL or PL/SQL

■

Loading XML Content using Java

■

Loading XML Content using C

■

Loading Large XML Files that Contain Small XML Documents

■

Loading Large XML Files using SQL*Loader

Path-based repository loading techniques:
■

Loading XML Documents into the Repository using DBMS_XDB

■

Loading Documents into the Repository using Protocols

Loading XML Content using SQL or PL/SQL
You can use a simple INSERT operation in SQL or PL/SQL to load an XML document
into the database. Before the document can be stored as an XMLType column or table,
you must convert it into an XMLType instance using one of the XMLType constructors.
See Also:
■

Chapter 4, "XMLType Operations"

■

"APIs for XML" on page 1-4

■

Oracle Database PL/SQL Packages and Types Reference for a
description of the XMLType constructors

XMLType constructors allow an XMLType instance to be created from different
sources, including VARCHAR, CLOB, and BFILE values. The constructors accept
additional arguments that reduce the amount of processing associated with XMLType
creation. For example, if you are sure that a given source XML document is valid, you
can provide an argument to the constructor that disables the type-checking that is
otherwise performed.

Using Oracle XML DB

3-5

Loading XML Content into Oracle XML DB

In addition, if the source data is not encoded in the database character set, an XMLType
instance can be constructed using a BFILE or BLOB value. The encoding of the source
data is specified through the character set id (csid) argument of the constructor.
Example 3–5 shows how to insert XML content into an XMLType table. Before making
this insertion, you must create a database directory object that points to the directory
containing the file to be processed. To do this, you must have the CREATE ANY
DIRECTORY privilege.
See Also: Oracle Database SQL Language Reference, Chapter 18,
under GRANT
Example 3–4 Creating a Database Directory
CREATE DIRECTORY xmldir AS path_to_folder_containing_XML_file;
Example 3–5 Inserting XML Content into an XMLType Table
INSERT INTO mytable2 VALUES (XMLType(bfilename('XMLDIR', 'purchaseOrder.xml'),
nls_charset_id('AL32UTF8')));

The value passed to nls_charset_id indicates that the encoding for the file to be
read is UTF-8.
When you use SQL INSERT to insert a large document containing collections into
XMLType tables (but not into XMLType columns), Oracle XML DB optimizes load time
and memory usage.
See Also: "Loading and Retrieving Large Documents with
Collections" on page 9-28

Loading XML Content using Java
Example 3–6 shows how to load XML content into Oracle XML DB by first creating an
XMLType instance in Java, given a Document Object Model (DOM).
Example 3–6 Inserting Content into an XMLType Table using Java
public void doInsert(Connection conn, Document doc)
throws Exception
{
String SQLTEXT = "INSERT INTO purchaseorder VALUES (?)";
XMLType xml = null;
xml = XMLType.createXML(conn,doc);
OraclePreparedStatement sqlStatement = null;
sqlStatement = (OraclePreparedStatement) conn.prepareStatement(SQLTEXT);
sqlStatement.setObject(1,xml);
sqlStatement.execute();
}

A simple bulk loader application is available on the Oracle Technology Network
(OTN) site at
http://www.oracle.com/technetwork/database-features/xmldb/overvi
ew/index.html. It shows how to load a directory of XML files into Oracle XML DB
using Java Database Connectivity (JDBC). JDBC is a set of Java interfaces to Oracle
Database.

3-6 Oracle XML DB Developer's Guide

Loading XML Content into Oracle XML DB

Loading XML Content using C
Example 3–7 shows how to insert XML content into an XMLType table using C code,
by creating an XMLType instance given a DOM.
Example 3–7 Inserting Content into an XMLType Table using C
#include "stdio.h"
#include 
#include 
#include 
#include 
OCIEnv *envhp;
OCIError *errhp;
OCISvcCtx *svchp;
OCIStmt *stmthp;
OCIServer *srvhp;
OCIDuration dur;
OCISession *sesshp;
oratext *username = "QUINE";
oratext *password = "************";
/* Replace with the real password. */
oratext *filename = "AMCEWEN-20021009123336171PDT.xml";
oratext *schemaloc = "http://localhost:8080/source/schemas/poSource/xsd/purchaseOrder.xsd";
/*--------------------------------------------------------*/
/* Execute a SQL statement that binds XML data
*/
/*--------------------------------------------------------*/
sword exec_bind_xml(OCISvcCtx *svchp, OCIError *errhp, OCIStmt *stmthp,
void *xml,
OCIType *xmltdo, OraText *sqlstmt)
{
OCIBind *bndhp1 = (OCIBind *) 0;
sword status = 0;
OCIInd ind = OCI_IND_NOTNULL;
OCIInd *indp = &ind;
if(status = OCIStmtPrepare(stmthp, errhp, (OraText *)sqlstmt,
(ub4)strlen((const char *)sqlstmt),
(ub4) OCI_NTV_SYNTAX, (ub4) OCI_DEFAULT))
return OCI_ERROR;
if(status = OCIBindByPos(stmthp, &bndhp1, errhp, (ub4) 1, (dvoid *) 0,
(sb4) 0, SQLT_NTY, (dvoid *) 0, (ub2 *)0,
(ub2 *)0, (ub4) 0, (ub4 *) 0, (ub4) OCI_DEFAULT))
return OCI_ERROR;
if(status = OCIBindObject(bndhp1, errhp, (CONST OCIType *) xmltdo,
(dvoid **) &xml, (ub4 *) 0,
(dvoid **) &indp, (ub4 *) 0))
return OCI_ERROR;
if(status = OCIStmtExecute(svchp, stmthp, errhp, (ub4) 1, (ub4) 0,
(CONST OCISnapshot*) 0, (OCISnapshot*) 0,
(ub4) OCI_DEFAULT))
return OCI_ERROR;
return OCI_SUCCESS;
}
/*--------------------------------------------------------*/
/* Initialize OCI handles, and connect
*/
/*--------------------------------------------------------*/
sword init_oci_connect()
{

. . .
}
/*--------------------------------------------------------*/
/* Free OCI handles, and disconnect
*/
/*--------------------------------------------------------*/

Using Oracle XML DB

3-7

Loading XML Content into Oracle XML DB

void free_oci()
{
. . .
}
void main()
{
OCIType *xmltdo;
xmldocnode *doc;
ocixmldbparam params[1];
xmlerr
err;
xmlctx *xctx;
oratext *ins_stmt;
sword
status;
xmlnode *root;
oratext buf[10000];
/* Initialize envhp, svchp, errhp, dur, stmthp */
init_oci_connect();
/* Get an XML context */
params[0].name_ocixmldbparam = XCTXINIT_OCIDUR;
params[0].value_ocixmldbparam = &dur;
xctx = OCIXmlDbInitXmlCtx(envhp, svchp, errhp, params, 1);
if (!(doc = XmlLoadDom(xctx, &err, "file", filename,
"schema_location", schemaloc, NULL)))
{
printf("Parse failed.\n");
return;
}
else
printf("Parse succeeded.\n");
root = XmlDomGetDocElem(xctx, doc);
printf("The xml document is :\n");
XmlSaveDom(xctx, &err, (xmlnode *)doc, "buffer", buf, "buffer_length", 10000, NULL);
printf("%s\n", buf);
/* Insert the document into my_table */
ins_stmt = (oratext *)"insert into purchaseorder values (:1)";
status = OCITypeByName(envhp, errhp, svchp, (const text *) "SYS",
(ub4) strlen((const char *)"SYS"), (const text *) "XMLTYPE",
(ub4) strlen((const char *)"XMLTYPE"), (CONST text *) 0,
(ub4) 0, OCI_DURATION_SESSION, OCI_TYPEGET_HEADER,
(OCIType **) &xmltdo);
if (status == OCI_SUCCESS)
{
status = exec_bind_xml(svchp, errhp, stmthp, (void *)doc,
xmltdo, ins_stmt);
}
if (status == OCI_SUCCESS)
printf ("Insert successful\n");
else
printf ("Insert failed\n");
/* Free XML instances */
if (doc)
XmlFreeDocument((xmlctx *)xctx, (xmldocnode *)doc);
/* Free XML CTX */
OCIXmlDbFreeXmlCtx(xctx);
free_oci();
}

3-8 Oracle XML DB Developer's Guide

Loading XML Content into Oracle XML DB

For simplicity in demonstrating this feature, this example does
not perform the password management techniques that a deployed
system normally uses. In a production environment, follow the Oracle
Database password management guidelines, and disable any sample
accounts. See Oracle Database Security Guide for password management
guidelines and other security recommendations.

Note:

See Also: Appendix A, "Oracle-Supplied XML Schemas and
Examples" for a complete listing of this example

Loading Large XML Files that Contain Small XML Documents
When loading large XML files consisting of a collection of smaller XML documents, it
is often more efficient to use Simple API for XML (SAX) parsing to break the file into a
set of smaller documents, and then insert those documents. SAX is an XML standard
interface provided by XML parsers for event-based applications.
You can use SAX to load a database table from very large XML files in the order of 30
MB or larger, by creating individual documents from a collection of nodes. You can
also bulk load XML files.
See Also:
■
■

http://www.saxproject.org/ for information about SAX
http://www.oracle.com/technetwork/database-features
/xmldb/overview/index.html, for an application example
that loads large files using SAX

Loading Large XML Files using SQL*Loader
Use SQL*Loader to load large amounts of XML data into Oracle Database.
SQL*Loader loads in one of two modes, conventional or direct path. Table 3–1
compares these modes.
Table 3–1

SQL*Loader – Conventional and Direct-Path Load Modes

Conventional Load Mode

Direct-Path Load Mode

Uses SQL to load data into Oracle Database. This
is the default mode.

Bypasses SQL and streams the data
directly into Oracle Database.

Advantage: Follows SQL semantics. For example
triggers are fired and constraints are checked.

Advantage: This loads data much faster
than the conventional load mode.

Disadvantage: This loads data slower than with the Disadvantage: SQL semantics is not obeyed.
direct load mode.
For example triggers are not fired and
constraints are not checked.

When loading LOBs with SQL*Loader direct-path load, much memory can be used. If
the message SQL*Loader 700 (out of memory) appears, then it is likely that
more rows are being included in each load call than can be handled by your operating
system and process memory. Workaround: use the ROWS option to read a smaller
number of rows in each data save.
See Also:

Chapter 35, "Loading XML Data using SQL*Loader"

Using Oracle XML DB

3-9

Loading XML Content into Oracle XML DB

Loading XML Documents into the Repository using DBMS_XDB
You can also store XML documents in Oracle XML DB Repository, and access these
documents using path-based rather than table-based techniques. To load an XML
document into the repository under a given path, use PL/SQL function DBMS_
XDB.createResource. Example 3–8 illustrates this.
Example 3–8 Inserting XML Content into the Repository using CREATERESOURCE
DECLARE
res BOOLEAN;
BEGIN
res := DBMS_XDB.createResource('/home/QUINE/purchaseOrder.xml',
bfilename('XMLDIR', 'purchaseOrder.xml'),
nls_charset_id('AL32UTF8'));
END;
/

Many operations for configuring and using Oracle XML DB are based on processing
one or more XML documents. Examples include registering an XML schema and
performing an XSL transformation. The easiest way to make these XML documents
available to Oracle Database is to load them into Oracle XML DB Repository.

Loading Documents into the Repository using Protocols
Oracle XML DB Repository can store XML documents that are either XML
schema-based or non-schema-based. It can also store content that is not XML data,
such as HTML files, image files, and Microsoft Word documents.
You can load XML documents from a local file system into Oracle XML DB Repository
using protocols such as WebDAV, from Windows Explorer or other tools that support
WebDAV. Figure 3–1 shows a simple drag and drop operation for copying the contents
of the SCOTT folder from the local hard drive to folder poSource in the Oracle
XML DB Repository.
Figure 3–1 Loading Content into the Repository using Windows Explorer

The copied folder might contain, for example, an XML schema document, an HTML
page, and some XSLT style sheets.

3-10 Oracle XML DB Developer's Guide

Character Sets of XML Documents

Character Sets of XML Documents
This section describes how character sets of XML documents are determined.

AL32UTF8 is the Oracle Database character set that is
appropriate for XMLType data. It is equivalent to the IANA registered
standard UTF-8 encoding, which supports all valid XML characters.

Caution:

Do not confuse Oracle Database database character set UTF8 (no
hyphen) with database character set AL32UTF8 or with character
encoding UTF-8. Database character set UTF8 has been superseded by
AL32UTF8. Do not use UTF8 for XML data. Character set UTF8
supports only Unicode version 3.1 and earlier. It does not support all
valid XML characters. AL32UTF8 has no such limitation.
Using database character set UTF8 for XML data could potentially stop
a system or affect security negatively. If a character that is not supported
by the database character set appears in an input-document element
name, a replacement character (usually "?") is substituted for it. This
terminates parsing and raises an exception. It can cause an
irrecoverable error.

XML Encoding Declaration
Each XML document is composed of units called entities. Each entity in an XML
document may use a different encoding for its characters. Entities that are stored in an
encoding other than UTF-8 or UTF-16 must begin with an XML declaration containing
an encoding specification indicating the character encoding in use. For example:


Entities encoded in UTF-16 must begin with the Byte Order Mark (BOM), as described
in Appendix F of the XML 1.0 Reference. For example, on big-endian platforms, the
BOM required of a UTF-16 data stream is #xFEFF.
In the absence of both the encoding declaration and the BOM, the XML entity is
assumed to be encoded in UTF-8. Because ASCII is a subset of UTF-8, ASCII entities
do not require an encoding declaration.
In many cases, external sources of information are available, besides the XML data, to
provide the character encoding in use. For example, the encoding of the data can be
obtained from the charset parameter of the Content-Type field in an HTTP(S)
request as follows:
Content-Type: text/xml; charset=ISO-8859-4

Character-Set Determination When Loading XML Documents into the Database
In releases prior to Oracle Database 10g release 1, all XML documents were assumed to
be in the database character set, regardless of the document encoding declaration.
Starting with Oracle Database 10g release 1, the document encoding is detected from
the encoding declaration when the document is loaded into the database.
However, if the XML data is obtained from a CLOB or VARCHAR value, then the
encoding declaration is ignored, because these two data types are always encoded in
the database character set.

Using Oracle XML DB 3-11

Character Sets of XML Documents

In addition, when loading data into Oracle XML DB, either through programmatic
APIs or transfer protocols, you can provide external encoding to override the
document encoding declaration. An error is raised if you try to load a schema-based
XML document that contains characters that are not legal in the determined encoding.
The following examples show different ways to specify external encoding:
■

Using PL/SQL function DBMS_XDB.createResource to create a file resource
from a BFILE, you can specify the file encoding with the CSID argument. If a zero
CSID is specified then the file encoding is auto-detected from the document
encoding declaration.
CREATE DIRECTORY xmldir AS '/private/xmldir';
CREATE OR REPLACE PROCEDURE loadXML(filename VARCHAR2, file_csid NUMBER) IS
xbfile BFILE;
RET
BOOLEAN;
BEGIN
xbfile := bfilename('XMLDIR', filename);
ret := DBMS_XDB.createResource('/public/mypurchaseorder.xml',
xbfile,
file_csid);
END;
/

■

Use the FTP protocol to load documents into Oracle XML DB. Use the quote
set_charset FTP command to indicate the encoding of the files to be loaded.
ftp> quote set_charset Shift_JIS
ftp> put mypurchaseorder.xml

■

Use the HTTP(S) protocol to load documents into Oracle XML DB. Specify the
encoding of the data to be transmitted to Oracle XML DB in the request header.
Content-Type: text/xml; charset= EUC-JP

Character-Set Determination When Retrieving XML Documents from the Database
XML documents stored in Oracle XML DB can be retrieved using a SQL client,
programmatic APIs, or transfer protocols. You can specify the encoding of the
retrieved data (except in Oracle Database releases prior to 10g, where XML data is
retrieved only in the database character set).
When XML data is stored as a CLOB or VARCHAR2 value, the encoding declaration, if
present, is always ignored for retrieval, just as for storage. The encoding of a retrieved
document can thus be different from the encoding explicitly declared in that
document.
The character set for an XML document retrieved from the database is determined in
the following ways:
■

SQL client – If a SQL client (such as SQL*Plus) is used to retrieve XML data, then
the character set is determined by the client-side environment variable NLS_LANG.
In particular, this setting overrides any explicit character-set declarations in the
XML data itself.
For example, if you set the client side NLS_LANG variable to AMERICAN_
AMERICA.AL32UTF8 and then retrieve an XML document with encoding EUC_JP
provided by declaration , the
character set of the retrieved document is AL32UTF8, not EUC_JP.

3-12 Oracle XML DB Developer's Guide

Overview of the W3C XML Schema Recommendation

See Also: Oracle Database Globalization Support Guide for information
about NLS_LANG
■

PL/SQL and APIs – Using PL/SQL or programmatic APIs, you can retrieve XML
data into VARCHAR, CLOB, or XMLType data types. As for SQL clients, you can
control the encoding of the retrieved data by setting NLS_LANG.
You can also retrieve XML data into a BLOB value using XMLType and URIType
methods. These let you specify the character set of the returned BLOB value. Here
is an example:
CREATE OR REPLACE FUNCTION getXML(pathname VARCHAR2, charset VARCHAR2)
RETURN BLOB IS
xblob BLOB;
BEGIN
SELECT XMLSERIALIZE(DOCUMENT e.RES AS BLOB ENCODING charset) INTO xblob
FROM RESOURCE_VIEW e WHERE equals_path(e.RES, pathname) = 1;
RETURN xblob;
END;
/

■

FTP – You can use the FTP quote set_nls_locale command to set the
character set:
ftp> quote set_nls_locale EUC-JP
ftp> get mypurchaseorder.xml

See Also:
■

FTP Quote Methods on page 28-10

HTTP(S) – You can use the Accept-Charset parameter in an HTTP(S) request:
/httptest/mypurchaseorder.xml 1.1 HTTP/Host: localhost:2345
Accept: text/*
Accept-Charset: iso-8859-1, utf-8

See Also:

Controlling Character Sets for HTTP(S) on page 28-20

Overview of the W3C XML Schema Recommendation
The W3C XML Schema Recommendation defines a standardized language for
specifying the structure, content, and certain semantics of a set of XML documents. An
XML schema can be considered the metadata that describes a class of XML documents.
The XML Schema Recommendation is described at:
http://www.w3.org/TR/xmlschema-0/

XML Instance Documents
Documents conforming to a given XML schema can be considered as members or
instances of the class defined by that XML schema. Consequently the term instance
document is often used to describe an XML document that conforms to a given XML
schema. The most common use of an XML schema is to validate that a given instance
document conforms to the rules defined by the XML schema.

Using Oracle XML DB 3-13

Overview of the W3C XML Schema Recommendation

XML Schema for Schemas
The W3C Schema working group publishes an XML schema, often referred to as the
"Schema for Schemas". This XML schema provides the definition, or vocabulary, of the
XML Schema language. All valid XML schemas can be considered to be members of
the class defined by this XML schema. An XML schema is thus an XML document that
conforms to the class defined by the XML schema published at
http://www.w3.org/2001/XMLSchema.

Editing XML Schemas
XML schemas can be authored and edited using any of the following:
■
■

■

A simple text editor, such as emacs or vi
An XML schema-aware editor, such as the XML editor included with Oracle
JDeveloper
An explicit XML schema-authoring tool, such as XMLSpy from Altova
Corporation

XML Schema Features
The XML Schema language defines 47 scalar data types. This provides for strong
typing of elements and attributes. The W3C XML Schema Recommendation also
supports object-oriented techniques such as inheritance and extension, hence you can
design XML schema with complex objects from base data types defined by the XML
Schema language. The vocabulary includes constructs for defining and ordering,
default values, mandatory content, nesting, repeated sets, and redefines. Oracle
XML DB supports all the constructs, except for redefines.

Text Representation of the Purchase Order XML Schema
Example 3–9 shows the purchase order XML schema as an XML file,
purchaseOrder.xsd.
Example 3–9 Purchase-Order XML Schema, purchaseOrder.xsd























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Overview of the W3C XML Schema Recommendation






























































Using Oracle XML DB 3-15

Overview of the W3C XML Schema Recommendation






























































3-16 Oracle XML DB Developer's Guide

Overview of the W3C XML Schema Recommendation










See Also: Example 3–10, "Annotated Purchase-Order XML
Schema, purchaseOrder.xsd" on page 3-20

Graphical Representation of the Purchase-Order XML Schema
Figure 3–2 shows the purchase-order XML schema displayed using XMLSpy. XMLSpy
is a graphical and user-friendly tool from Altova Corporation for creating and editing
XML schema and XML documents. See http://www.altova.com for details.
XMLSpy also supports WebDAV and FTP protocols hence can directly access and edit
content stored in Oracle XML DB Repository.
Figure 3–2 XMLSpy Graphical Representation of the PurchaseOrder XML Schema

The purchase order XML schema demonstrates some key features of a typical XML
document:
■

Global element PurchaseOrder is an instance of the complexType
PurchaseOrderType

Using Oracle XML DB 3-17

Using XML Schema with Oracle XML DB

■

PurchaseOrderType defines the set of nodes that make up a PurchaseOrder
element

■

LineItems element consists of a collection of LineItem elements

■

Each LineItem element consists of two elements: Description and Part

■

Part element has attributes Id, Quantity, and UnitPrice

Using XML Schema with Oracle XML DB
This section describes the use of XML Schema with Oracle XML DB.

Why Use XML Schema with Oracle XML DB?
The following paragraphs describe the main reasons for using XML schema with
Oracle XML DB.

Validating Instance Documents with XML Schema
The most common usage of XML Schema is as a mechanism for validating that
instance documents conform to a given XML schema. The XMLType methods
isSchemaValid() and schemaValidate() validate the contents of an instance
document stored as XMLType.

Constraining Instance Documents for Business Rules or Format Compliance
An XML schema can also be used as a constraint when creating tables or columns of
XMLType. For example, the XMLType is constrained to storing XML documents
compliant with one of the global elements defined by the XML schema.

Defining How XMLType Contents Must be Stored in the Database
Oracle XML DB also uses XML Schema as a mechanism for defining how the contents
of an XMLType instance should be stored inside the database. All storage models
support the use of XML Schema: binary XML, structured, unstructured, and hybrid (a
combination of structured and unstructured). See "XMLType Storage Models" on
page 1-14 for information on the available storage models for XMLType.

Structured Storage of XML Documents
Structured storage of XML documents is based on decomposing the content of the
document into a set of SQL objects. These SQL objects are based on the SQL 1999 Type
framework. When an XML schema is registered with Oracle XML DB, the required
SQL type definitions are automatically generated from the XML schema.
A SQL type definition is generated from each complexType defined by the XML
schema. Each element or attribute defined by the complexType becomes a SQL
attribute in the corresponding SQL type. Oracle XML DB automatically maps the 47
scalar data types defined by the XML Schema Recommendation to the 19 scalar data
types supported by SQL. A varray type is generated for each element and this can
occur multiple times.
The generated SQL types allow XML content, compliant with the XML schema, to be
decomposed and stored in the database as a set of objects without any loss of
information. When the document is ingested the constructs defined by the XML
schema are mapped directly to the equivalent SQL types.

3-18 Oracle XML DB Developer's Guide

Using XML Schema with Oracle XML DB

This lets Oracle XML DB leverage the full power of Oracle Database when managing
XML and can lead to significant reductions in the amount of space required to store
the document. It can also reduce the amount of memory required to query and update
XML content.

Annotating an XML Schema to Control Naming, Mapping, and Storage
The W3C XML Schema Recommendation defines an annotation mechanism that lets
vendor-specific information be added to an XML schema. Oracle XML DB uses this
mechanism to control the mapping between the XML schema and database features.
You can use XML schema annotations to do the following:
■
■

■

Specify which database tables are used to store the XML data.
Override the default mapping between XML Schema data types and SQL data
types, for structured storage.
Name the database objects and attributes that are created to store XML data (for
structured storage).

Controlling How Collections Are Stored for Object-Relational XMLType Storage
When you register an XML schema for data that is stored object-relationally and you
set registration parameter GENTABLES to TRUE, default tables are created
automatically to store the associated XML instance documents.
Order is preserved among XML collection elements when they are stored. The result is
an ordered collection.2 You can store data in an ordered collection in these ways:
■

■

Varray in a table. Each element in the collection is mapped to a SQL object. The
collection of SQL objects is stored as a set of rows in a table, called an ordered
collection table (OCT). By default, all collections are stored in OCTs. This default
behavior corresponds to the XML schema annotation
xdb:storeVarrayAsTable = "true" (default value).
Varray in a LOB. Each element in the collection is mapped to a SQL object. The
entire collection of SQL objects is serialized as a varray and stored in a LOB
column. To store a given collection as a varray in a LOB, use XML schema
annotation xdb:storeVarrayAsTable = "false".

You can also use out-of-line storage for an ordered collection. This corresponds to XML
schema annotation SQLInline = "false", and it means that a varray of REFs in
the collection table or LOB tracks the collection content, which is stored out of line.
There is no requirement to annotate an XML schema before using it. Oracle XML DB
uses a set of default assumptions when processing an XML schema that contains no
annotations.
If you do not supply any of the annotations mentioned in this section, then Oracle
XML DB stores a collection as a heap-based OCT. You can force OCTs to be stored as
index-organized tables (IOTs) instead, by passing REGISTER_NT_AS_IOT in the
OPTIONS parameter of DBMS_XMLSCHEMA.registerSchema.

2

If you use XML schema annotation maintainOrder = "false", then an unordered
collection is used instead of an ordered collection. Oracle recommends that you use ordered
collections (maintainOrder = "true") for XML data, to preserve document order. By
default, attribute maintainOrder is true.

Using Oracle XML DB 3-19

Using XML Schema with Oracle XML DB

Note: Use heap-based OCTs, not IOTs, unless you are explicitly
advised by Oracle to use IOTs. IOT storage has these significant
limitations:
■
■

It disables partitioning of the collection tables (IOTs).
It supports only document-level Oracle Text indexes. It disables
indexes that are element-specific or attribute-specific.

See also: Chapter 12, "Full-Text Search Over XML Data" for
information about using Oracle Text with XML data.

Note:

In releases prior to Oracle Database 11g Release 1:

■

OCTs were stored as IOTs by default.

■

The default value for xdb:storeVarrayAsTable was false.

See Also:
■

■
■

■

"Structured Storage of XML Schema-Based Data" on page 7-32
for information about collection storage when you create
XMLType tables and columns manually using structured
storage
Chapter 7, "XML Schema Storage and Query: Basic"
"Setting Annotation Attribute SQLInline to false for
Out-Of-Line Storage" on page 9-4
Partitioning XMLType Tables and Columns Stored
Object-Relationally on page 9-10

Declaring the Oracle XML DB Namespace
Before annotating an XML schema you must first declare the Oracle XML DB
namespace. The Oracle XML DB namespace is defined as:
http://xmlns.oracle.com/xdb
The namespace is declared in the XML schema by adding a namespace declaration
such as the following to the root element of the XML schema:
xmlns:xdb="http://xmlns.oracle.com/xdb"
Note the use of a namespace prefix (xdb). This makes it possible to abbreviate the
namespace to xdb when adding annotations.
Example 3–10 shows the beginning of the PurchaseOrder XML schema with
annotations. See Example A–1 on page A-30 for the complete schema listing.
Example 3–10

Annotated Purchase-Order XML Schema, purchaseOrder.xsd







3-20 Oracle XML DB Developer's Guide

Using XML Schema with Oracle XML DB


name="Reject" type="RejectionType" minOccurs="0" xdb:SQLName="REJECTION"/>
name="Requestor" type="RequestorType" xdb:SQLName="REQUESTOR"/>
name="User" type="UserType" minOccurs="1" xdb:SQLName="USERID"/>
name="CostCenter" type="CostCenterType" xdb:SQLName="COST_CENTER"/>
name="ShippingInstructions" type="ShippingInstructionsType"
xdb:SQLName="SHIPPING_INSTRUCTIONS"/>
























































Using Oracle XML DB 3-21

Using XML Schema with Oracle XML DB




































































3-22 Oracle XML DB Developer's Guide

Using XML Schema with Oracle XML DB




















The PurchaseOrder XML schema defines the following two namespaces:
■

■

http://www.w3c.org/2001/XMLSchema. This is reserved by W3C for the
Schema for Schemas.
http://xmlns.oracle.com/xdb. This is reserved by Oracle for the Oracle
XML DB schema annotations.

The PurchaseOrder schema uses several annotations, including the following:
■

■

defaultTable annotation in the PurchaseOrder element. This specifies that
XML documents, compliant with this XML schema are stored in a database table
called purchaseorder.
SQLType annotation.
The first occurrence of SQLType specifies that the name of the SQL type generated
from complexType element PurchaseOrderType is purchaseorder_t.
The second occurrence of SQLType specifies that the name of the SQL type
generated from the complexType element LineItemType is lineitem_t and
the SQL type that manages the collection of LineItem elements is lineitem_v.

■

SQLName annotation. This provides an explicit name for each SQL attribute of
purchaseorder_t.

Figure 3–3 shows the XMLSpy Oracle tab, which facilitates adding Oracle XML DB
schema annotations to an XML schema while working in the graphical editor.

Using Oracle XML DB 3-23

Using XML Schema with Oracle XML DB

Figure 3–3 XMLSpy Showing Support for Oracle XML DB Schema Annotations

Registering an XML Schema with Oracle XML DB
For an XML schema to be useful to Oracle XML DB you must first register it with
Oracle XML DB. After it has been registered, it can be used for validating XML
documents and for creating XMLType tables and columns bound to the XML schema.
Two items are required to register an XML schema with Oracle XML DB:
■
■

The XML schema document
A string that can be used as a unique identifier for the XML schema, after it is
registered with Oracle Database. Instance documents use this unique identifier to
identify themselves as members of the class defined by the XML schema. The
identifier is typically in the form of a URL, and is often referred to as the schema
location hint or document location hint.

You register an XML schema using PL/SQL procedure DBMS_
XMLSCHEMA.registerSchema. Example 3–11 illustrates this. By default, when an
XML schema is registered, Oracle XML DB automatically generates all of the SQL
object types and XMLType tables required to manage the instance documents. An XML
schema can be registered as global or local.

3-24 Oracle XML DB Developer's Guide

Using XML Schema with Oracle XML DB

See Also:
■

■
■

Example 3–11

"Delete and Reload Documents Before Registering Their XML
Schema" on page 7-8 for considerations to keep in mind when
you register an XML schema
"Local and Global XML Schemas" on page 7-14
Oracle Database PL/SQL Packages and Types Reference for
information about DBMS_XMLSCHEMA.registerSchema

Registering an XML Schema using DBMS_XMLSCHEMA.REGISTERSCHEMA

BEGIN
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'http://localhost:8080/source/schemas/poSource/xsd/purchaseOrder.xsd',
SCHEMADOC => XDBURIType('/source/schemas/poSource/xsd/purchaseOrder.xsd').getCLOB(),
LOCAL
=> TRUE,
GENTYPES => TRUE,
GENTABLES => TRUE);
END;
/

In Example 3–11, the unique identifier for the XML schema is:
http://localhost:8080/source/schemas/poSource/xsd/purchaseOrder.xsd

The XML schema document was previously loaded into Oracle XML DB Repository at
this path: /source/schemas/poSource/xsd/purchaseOrder.xsd.
During XML schema registration, an XDBURIType accesses the content of the XML
schema document, based on its location in the repository. Options passed to procedure
registerSchema specify that the schema in Example 3–11 is to be registered as a
local XML schema, and that SQL objects, and that tables are to be generated during the
registration process.
PL/SQL procedure DBMS_XMLSCHEMA.registerSchema performs the following
operations:
■

Parses and validates the XML schema.

■

Creates a set of entries in Oracle Data Dictionary that describe the XML schema.

■

■

Creates a set of SQL object definitions, based on complexType elements defined
in the XML schema.
Creates an XMLType table for each global element defined by the XML schema.
See Also:

"Local and Global XML Schemas" on page 7-14

SQL Types and Tables Created During XML Schema Registration
Example 3–12 illustrates the creation of object types during XML schema registration
with Oracle XML DB.
Example 3–12

Objects Created During XML Schema Registration

DESCRIBE purchaseorder_t
purchaseorder_t is NOT FINAL
Name
Null?
----------------------------------------- -------SYS_XDBPD$
REFERENCE
ACTIONS

Type
---------------------------XDB.XDB$RAW_LIST_T
VARCHAR2(30 CHAR)
ACTIONS_T

Using Oracle XML DB 3-25

Using XML Schema with Oracle XML DB

REJECTION
REQUESTOR
USERID
COST_CENTER
SHIPPING_INSTRUCTIONS
SPECIAL_INSTRUCTIONS
LINEITEMS

REJECTION_T
VARCHAR2(128 CHAR)
VARCHAR2(10 CHAR)
VARCHAR2(4 CHAR)
SHIPPING_INSTRUCTIONS_T
VARCHAR2(2048 CHAR)
LINEITEMS_T

DESCRIBE lineitems_t
lineitems_t is NOT FINAL
Name
Null?
----------------------------------------- -------SYS_XDBPD$
LINEITEM

Type
---------------------------XDB.XDB$RAW_LIST_T
LINEITEM_V

DESCRIBE lineitem_v
lineitem_v VARRAY(2147483647) OF LINEITEM_T
LINEITEM_T is NOT FINAL
Name
Null?
----------------------------------------- -------SYS_XDBPD$
ITEMNUMBER
DESCRIPTION
PART

Type
---------------------------XDB.XDB$RAW_LIST_T
NUMBER(38)
VARCHAR2(256 CHAR)
PART_T

This example shows that SQL type definitions were created when the XML schema
was registered with Oracle XML DB. These SQL type definitions include:
■

■

purchaseorder_t. This type is used to persist the SQL objects generated from a
PurchaseOrder element. When an XML document containing a
PurchaseOrder element is stored in Oracle XML DB the document is broken up,
and the contents of the document are stored as an instance of purchaseorder_t.
lineitems_t, lineitem_v, and lineitem_t. These types manage the
collection of LineItem elements that may be present in a PurchaseOrder
document. Type lineitems_t consists of a single attribute lineitem, defined as
an instance of type lineitem_v. Type lineitem_v is defined as a varray of
linteitem_t objects. There is one instance of the lineitem_t object for each
LineItem element in the document.

Working with Large XML Schemas
Several issues can arise when working with large, complex XML schemas.
Sometimes, you encounter one of these errors when you register an XML schema or
you create a table that is based on a global element defined by an XML schema:
■

ORA-01792: maximum number of columns in a table or view is
1000

■

ORA-04031: unable to allocate string bytes of shared memory
("string","string","string","string")

These errors are raised when an attempt is made to create an XMLType table or column
based on a global element and the global element is defined as a complexType that
contains a very large number of element and attribute definitions.
The errors are raised only when creating an XMLType table or column that uses
object-relational storage. In this case, the table or column is persisted using a SQL type,
and each object attribute defined by the SQL type counts as one column in the
underlying table. If the SQL type contains object attributes that are based on other SQL
types, then the attributes defined by those types also count as columns in the
underlying table.

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Using XML Schema with Oracle XML DB

If the total number of object attributes in all of the SQL types exceeds the Oracle
Database limit of 1000 columns in a table, then the storage table cannot be created.
When the total number of elements and attributes defined by a complexType reaches
1000, it is not possible to create a single table that can manage the SQL objects that are
generated when an instance of that type is stored in the database.
Tip: You can use the following query to determine the number of
columns for a given XMLType table stored object-relationally:
SELECT count(*) FROM USER_TAB_COLS WHERE TABLE_NAME = ''

where  is the table you want to check.
Error ORA-01792 reports that the 1000-column limit has been exceeded. Error
ORA-04031 reports that memory is insufficient during the processing of a large
number of element and attribute definitions.
To resolve this problem of having too many element and attribute definitions, you
must reduce the total number of object attributes in the SQL types that are used to
create the storage tables.
There are two ways to achieve this reduction:
■

■

Use a top-down technique, with multiple XMLType tables that manage the XML
documents. This reduces the number of SQL attributes in the SQL type hierarchy
for a given storage table. As long as none of the tables need to manage more than
1000 object attributes, the problem is resolved.
Use a bottom-up technique, which reduces the number of SQL attributes in the
SQL type hierarchy, collapsing some elements and attributes defined by the XML
schema so that they are stored as a single CLOB value.

Both techniques rely on annotating the XML schema to define how a particular
complexType is stored in the database.
For the top-down technique, annotations SQLInline = "false" and
defaultTable force some subelements in the XML document to be stored as rows in
a separate XMLType table. Oracle XML DB maintains the relationship between the two
tables using a REF of XMLType. Good candidates for this approach are XML schemas
that do either of the following:
■

■

Define a choice, where each element within the choice is defined as a
complexType
Define an element based on a complexType that contains a large number of element
and attribute definitions

The bottom-up technique involves reducing the total number of attributes in the SQL
object types by choosing to store some of the lower-level complexType elements as
CLOB values, rather than as objects. This is achieved by annotating the complexType
or the usage of the complexType with SQLType = "CLOB".
Which technique you use depends on the application and the type of queries and
updates to be performed against the data.

Working with Global Elements
By default, when an XML schema is registered with the database, Oracle XML DB
generates a default table for each global element defined by the XML schema.
You can use attribute xdb:defaultTable to specify the name of the default table for
a given global element. Each xdb:defaultTable attribute value you provide must

Using Oracle XML DB 3-27

Using XML Schema with Oracle XML DB

be unique among all schemas registered by a given database user. If you do not supply a
nonempty default table name for some element, then a unique name is provided
automatically.
In practice, however, you do not want to create a default table for most global
elements. Elements that never serve as the root element for an XML instance document
do not need default tables—such tables are never used. Creating default tables for all
global elements can lead to significant overhead in processor time and space used,
especially if an XML schema contains a large number of global element definitions.
As a general rule, then, you want to prevent the creation of a default table for any
global element (or any local element stored out of line) that you are sure will not be
used as a root element in any document. You can do this in one of the following ways:
■

■

Add the annotation xdb:defaultTable = "" (empty string) to the definition of
each global element that will not appear as the root element of an XML instance
document. Using this approach, you allow automatic default-table creation, in
general, and you prohibit it explicitly where needed, using xdb:defaultTable
= "".
Set parameter GENTABLES to FALSE when registering the XML schema, and then
manually create the default table for each global element that can legally appear as
the root element of an instance document. Using this approach, you inhibit
automatic default-table creation, and you create only the tables that are needed, by
hand.

Creating XML Schema-Based XMLType Columns and Tables
After an XML schema has been registered with Oracle XML DB, it can be referenced
when defining tables that contain XMLType columns or creating XMLType tables.
If you specify no storage model when creating an XMLType table or column for XML
schema-based data, then the storage model used is that specified during registration of
the referenced XML schema. If no storage model was specified for the XML schema
registration, then object-relational storage is used.
Example 3–13 shows how to manually create table purchaseorder, the default table
for PurchaseOrder elements.
Example 3–13

Creating an XMLType Table that Conforms to an XML Schema

CREATE TABLE purchaseorder OF XMLType
XMLSCHEMA "http://localhost:8080/source/schemas/poSource/xsd/purchaseOrder.xsd"
ELEMENT "PurchaseOrder"
VARRAY "XMLDATA"."ACTIONS"."ACTION"
STORE AS TABLE action_table
((PRIMARY KEY (NESTED_TABLE_ID, SYS_NC_ARRAY_INDEX$)))
VARRAY "XMLDATA"."LINEITEMS"."LINEITEM"
STORE AS TABLE lineitem_table
((PRIMARY KEY (NESTED_TABLE_ID, SYS_NC_ARRAY_INDEX$)));

Each member of the varray that manages the collection of Action elements is stored
in the ordered collection table action_table. Each member of the varray that
manages the collection of LineItem elements is stored as a row in ordered collection
table lineitem_table. The ordered collection tables are heap-based. Because of the
PRIMARY KEY specification, they automatically contain pseudocolumn NESTED_
TABLE_ID and column SYS_NC_ARRAY_INDEX$, which are required to link them
back to the parent column.

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This CREATE TABLE statement is equivalent to the CREATE TABLE statement that is
generated automatically by Oracle XML DB when you set parameter GENTABLES to
TRUE during XML schema registration. By default, the value of XML schema
annotation storeVarrayAsTable is true, which automatically generates ordered
collection tables (OCTs) for collections during XML schema registration. These OCTs
are given system-generated names, which can be difficult to work with. You can give
them more meaningful names using the SQL statement RENAME TABLE.
The CREATE TABLE statement in Example 3–13 corresponds to a purchase-order
document with a single level of nesting: The varray that manages the collection of
LineItem elements is ordered collection table lineitem_table.
What if you had a different XML schema that had, say, a collection of Shipment
elements inside a Shipments element that was, in turn, inside a LineItem element?
In that case, you could create the table manually as shown in Example 3–14.
Example 3–14

Creating an XMLType Table for Nested Collections

CREATE TABLE purchaseorder OF XMLType
XMLSCHEMA "http://localhost:8080/source/schemas/poSource/xsd/purchaseOrder.xsd"
ELEMENT "PurchaseOrder"
VARRAY "XMLDATA"."ACTIONS"."ACTION"
STORE AS TABLE action_table
((PRIMARY KEY (NESTED_TABLE_ID, SYS_NC_ARRAY_INDEX$)))
VARRAY "XMLDATA"."LINEITEMS"."LINEITEM"
STORE AS TABLE lineitem_table
((PRIMARY KEY (NESTED_TABLE_ID, SYS_NC_ARRAY_INDEX$))
VARRAY "SHIPMENTS"."SHIPMENT"
STORE AS TABLE shipments_table
((PRIMARY KEY (NESTED_TABLE_ID,
SYS_NC_ARRAY_INDEX$))));

A SQL*Plus DESCRIBE statement can be used to view information about an XMLType
table, as shown in Example 3–15.
Example 3–15

Using DESCRIBE with an XML Schema-Based XMLType Table

DESCRIBE purchaseorder
Name
Null?
Type
----------------------------------------- -------- ---------------------------TABLE of SYS.XMLTYPE(XMLSchema
"http://localhost:8080/source/schemas/poSource/xsd/purchaseOrder.xsd"
Element "PurchaseOrder") STORAGE Object-relational TYPE "PURCHASEORDER_T"

The output of the DESCRIBE statement of Example 3–15 shows the following
information about table purchaseorder:
■
■

The table is an XMLType table
The table is constrained to storing PurchaseOrder documents as defined by the
PurchaseOrder XML schema

■

Rows in this table are stored as a set of objects in the database

■

SQL type purchaseorder_t is the base object for this table

Default Tables
The XML schema in Example 3–13 specifies that the PurchaseOrder table is the
default table for PurchaseOrder elements. When an XML document compliant with
the XML schema is inserted into Oracle XML DB Repository using protocols or
Using Oracle XML DB 3-29

Identifying XML Schema Instance Documents

PL/SQL, the content of the XML document is stored as a row in the purchaseorder
table.
When an XML schema is registered as a global schema, you must grant the
appropriate access rights on the default table to all other users of the database, before
they can work with instance documents that conform to the globally registered XML
schema.
See Also:

"Local and Global XML Schemas" on page 7-14

Identifying XML Schema Instance Documents
Before an XML document can be inserted into an XML schema-based XMLType table
or column the document must identify the associated XML schema. There are two
ways to do this:
■

■

Explicitly identify the XML schema when creating the XMLType. This can be done
by passing the name of the XML schema to the XMLType constructor, or by
invoking XMLType method createSchemaBasedXML().
Use the XMLSchema-instance mechanism to explicitly provide the required
information in the XML document. This option can be used when working with
Oracle XML DB.

The advantage of the XMLSchema-instance mechanism is that it lets the Oracle
XML DB protocol servers recognize that an XML document inserted into Oracle
XML DB Repository is an instance of a registered XML schema. The content of the
instance document is automatically stored in the default table specified by that XML
schema.
The XMLSchema-instance mechanism is defined by the W3C XML Schema working
group. It is based on adding attributes that identify the target XML schema to the root
element of the instance document. These attributes are defined by the
XMLSchema-instance namespace.
To identify an instance document as a member of the class defined by a particular
XML schema you must declare the XMLSchema-instance namespace by adding a
namespace declaration to the root element of the instance document. For example:
xmlns:xsi = http://www.w3.org/2001/XMLSchema-instance
Once the XMLSchema-instance namespace has been declared and given a
namespace prefix, attributes that identify the XML schema can be added to the root
element of the instance document. In the preceding example, the namespace prefix for
the XMLSchema-instance namespace was defined as xsi. This prefix can then be
used when adding the XMLSchema-instance attributes to the root element of the
instance document.
Which attributes must be added depends on several factors. There are two
possibilities, noNamespaceSchemaLocation and schemaLocation. Depending on
the XML schema, one or both of these attributes is required to identify the XML
schemas that the instance document is associated with.

Attributes noNamespaceSchemaLocation and schemaLocation
If the target XML schema does not declare a target namespace, the
noNamespaceSchemaLocation attribute is used to identify the XML schema. The
value of the attribute is the schema location hint. This is the unique identifier passed to
PL/SQL procedure DBMS_XMLSCHEMA.registerSchema when the XML schema is
registered with the database.
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For XML schema purchaseOrder.xsd, the correct definition of the root element of
the instance document would read as follows:


If the target XML schema declares a target namespace, then the schemaLocation
attribute is used to identify the XML schema. The value of this attribute is a pair of
values separated by a space:
■
■

the value of the target namespace declared in the XML schema
the schema location hint, the unique identifier passed to procedure DBMS_
XMLSCHEMA.registerSchema when the schema is registered with the database

For example, assume that the PurchaseOrder XML schema includes a target
namespace declaration. The root element of the schema would look like this:



In this case, the correct form of the root element of the instance document would read
as follows:


Dealing with Multiple Namespaces
When the XML schema includes elements defined in multiple namespaces, an entry
must occur in the schemaLocation attribute for each of the XML schemas. Each
entry consists of the namespace declaration and the schema location hint. The entries are
separated from each other by one or more whitespace characters. If the primary XML
schema does not declare a target namespace, then the instance document also needs to
include a noNamespaceSchemaLocation attribute that provides the schema location
hint for the primary XML schema.

Enforcing XML Data Integrity using the Database
One advantage of using Oracle XML DB to manage XML content is that SQL can be
used to supplement the functionality provided by XML schema. Combining the power
of SQL and XML with the ability of the database to enforce rules makes the database a
powerful framework for managing XML content.
Only well-formed XML documents can be stored in XMLType tables or columns. A
well-formed XML document is one that conforms to the syntax of the XML version
declared in its XML declaration. This includes having a single root element, properly
nested tags, and so forth. Additionally, if the XMLType table or column is constrained
to an XML schema, only documents that conform to that XML schema can be stored in
that table or column. Any attempt to store or insert any other kind of XML document
Using Oracle XML DB 3-31

Enforcing XML Data Integrity using the Database

in an XML schema-based XMLType raises an error. Example 3–16 illustrates this.
Example 3–16

Error From Attempting to Insert an Incorrect XML Document

INSERT INTO purchaseorder
VALUES (XMLType(bfilename('XMLDIR', 'Invoice.xml'), nls_charset_id('AL32UTF8')))
VALUES (XMLType(bfilename('XMLDIR', 'Invoice.xml'), nls_charset_id('AL32UTF8')))
*
ERROR at line 2:
ORA-19007: Schema - does not match expected
http://localhost:8080/source/schemas/poSource/xsd/purchaseOrder.xsd.

Such an error only occurs when content is inserted directly into an XMLType table. It
indicates that Oracle XML DB did not recognize the document as a member of the
class defined by the XML schema. For a document to be recognized as a member of the
class defined by the schema, the following conditions must be true:
■

■

The name of the XML document root element must match the name of global
element used to define the XMLType table or column.
The XML document must include the appropriate attributes from the
XMLSchema-instance namespace, or the XML document must be explicitly
associated with the XML schema using the XMLType constructor or XMLType
method createSchemaBasedXML().

If the constraining XML schema declares a targetNamespace, then the instance
documents must contain the appropriate namespace declarations to place the root
element of the document in the targetNamespace defined by the XML schema.
XML constraints are enforced only within individual XML
documents. Database (SQL) constraints are enforced across sets of
XML documents.

Note:

Comparing Partial to Full XML Schema Validation
This section describes the differences between partial and full XML schema validation
used when inserting XML documents into the database.

Partial Validation
For binary XML storage, Oracle XML DB performs a full validation whenever an XML
document is inserted into an XML schema-based XMLType table or column. For all
other models of XML storage, Oracle XML DB performs only a partial validation of the
document. This is because, except for binary XML storage, complete XML schema
validation is quite costly, in terms of performance.
Partial validation ensures only that all of the mandatory elements and attributes are
present, and that there are no unexpected elements or attributes in the document. That
is, it ensures only that the structure of the XML document conforms to the SQL data
type definitions that were derived from the XML schema. Partial validation does not
ensure that the instance document is fully compliant with the XML schema.
Example 3–17 provides an example of failing partial validation while inserting an
XML document into table PurchaseOrder, which is stored object-relationally.
Example 3–17

Error When Inserting Incorrect XML Document (Partial Validation)

INSERT INTO purchaseorder
VALUES(XMLType(bfilename('XMLDIR', 'InvalidElement.xml'),

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Enforcing XML Data Integrity using the Database

nls_charset_id('AL32UTF8')));
VALUES(XMLType(bfilename('XMLDIR', 'InvalidElement.xml'),
*
ERROR at line 2:
ORA-30937: No schema definition for 'UserName' (namespace '##local') in parent
'/PurchaseOrder'

Full Validation
Loading XML data into XML schema-based binary XML storage causes full validation
against the target XML schemas. Otherwise, regardless of storage model, you can force
full validation of XML instance documents against an XML schema at any time, using
either of the following:
■

Table level CHECK constraint

■

PL/SQL BEFORE INSERT trigger

Both approaches ensure that only valid XML documents can be stored in the XMLType
table.
The advantage of a TABLE CHECK constraint is that it is easy to code. The
disadvantage is that it is based on Oracle SQL function XMLisValid, so it can only
indicate whether or not the XML document is valid. If an XML document is invalid, a
TABLE CHECK constraint cannot provide any information as to why it is invalid.
A BEFORE INSERT trigger requires slightly more code. The trigger validates the XML
document by invoking XMLType method schemaValidate(). The advantage of
using schemaValidate() is that the exception raised provides additional
information about what was wrong with the instance document. Using a BEFORE
INSERT trigger also makes it possible to attempt corrective action when an invalid
document is encountered.
Full XML Schema Validation Costs Processing Time and Memory Usage Unless you are using
binary XML storage, full XML schema validation costs processing time and memory.
You should thus perform full XML schema validation only when necessary. If you can
rely on your application to validate an XML document, you can obtain higher overall
throughput with non-binary XML storage, by avoiding the overhead associated with
full validation. If you cannot be sure about the validity of incoming XML documents,
you can rely on the database to ensure that an XMLType table or column contains only
schema-valid XML documents.
Example 3–18 shows how to force a full XML schema validation by adding a CHECK
constraint to an XMLType table. In Example 3–18, the XML document
InvalidReference is a not valid with respect to the XML schema. The XML schema
defines a minimum length of 18 characters for the text node associated with the
Reference element. In this document, the node contains the value
SBELL-20021009, which is only 14 characters long. Partial validation would not
catch this error. Unless the constraint or trigger is present, attempts to insert this
document into the database would succeed.
Example 3–18

Forcing Full XML Schema Validation using a CHECK Constraint

ALTER TABLE purchaseorder
ADD CONSTRAINT validate_purchaseorder
CHECK (XMLIsValid(OBJECT_VALUE) = 1);
Table altered.
INSERT INTO purchaseorder

Using Oracle XML DB 3-33

Enforcing XML Data Integrity using the Database

VALUES (XMLType(bfilename('XMLDIR', 'InvalidReference.xml'),
nls_charset_id('AL32UTF8')));
INSERT INTO purchaseorder
*
ERROR at line 1:
ORA-02290: check constraint (QUINE.VALIDATE_PURCHASEORDER) violated

Pseudocolumn OBJECT_VALUE can be used to access the content of an XMLType table
from within a trigger. Example 3–19 illustrates this, showing how to use a BEFORE
INSERT trigger to validate that the data being inserted into the XMLType table
conforms to the specified XML schema.
Example 3–19

Enforcing Full XML Schema Validation using a BEFORE INSERT Trigger

CREATE OR REPLACE TRIGGER validate_purchaseorder
BEFORE INSERT ON purchaseorder
FOR EACH ROW
BEGIN
IF (:new.OBJECT_VALUE IS NOT NULL) THEN :new.OBJECT_VALUE.schemavalidate();
END IF;
END;
/
INSERT INTO purchaseorder
VALUES (XMLType(bfilename('XMLDIR', 'InvalidReference.xml'),
nls_charset_id('AL32UTF8')));
VALUES (XMLType( bfilename('XMLDIR', 'InvalidReference.xml'),
*
ERROR at line 2:
ORA-31154: invalid XML document
ORA-19202: Error occurred in XML processing
LSX-00221: "SBELL-20021009" is too short (minimum length is 18)
ORA-06512: at "SYS.XMLTYPE", line 354
ORA-06512: at "QUINE.VALIDATE_PURCHASEORDER", line 3
ORA-04088: error during execution of trigger 'QUINE.VALIDATE_PURCHASEORDER'

Enforcing Referential Integrity using SQL Constraints
The W3C XML Schema Recommendation defines a powerful language for defining the
contents of an XML document. However, there are some simple data management
concepts that are not currently addressed by the W3C XML Schema Recommendation.
These include the ability to ensure that the value of an element or attribute has either
of these properties:
■
■

It is unique across a set of XML documents (a UNIQUE constraint).
It exists in a particular data source that is outside of the current document
(FOREIGN KEY constraint).

With Oracle XML DB, however, you can enforce such constraints. The mechanisms
that you use to enforce integrity on XML data are the same mechanisms that you use
to enforce integrity on relational data. Simple rules, such as uniqueness and
foreign-key relationships, can be enforced by specifying constraints. More complex
rules can be enforced by specifying database triggers.
Oracle XML DB lets you use the database to enforce business rules on XML content, in
addition to enforcing rules that can be specified using XML Schema constructs. The
database enforces these business rules regardless of whether XML is inserted directly

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into a table or uploaded using one of the protocols supported by Oracle XML DB
Repository.
Example 3–20, Example 3–21, and Example 3–22 illustrate how you can use SQL
constraints to enforce referential integrity. Example 3–20 defines a uniqueness
constraint on an XMLType table that is stored as binary XML. It defines a virtual
column, using the Reference element in a purchase-order document. The uniqueness
constraint reference_is_unique ensures that the value of node
/PurchaseOrder/Reference/text() is unique across all documents that are
stored in the table.
"Partitioning or Constraining Binary XML Data using
Virtual Columns" on page 3-3

See Also:

Example 3–20

Constraining a Binary XML Table using a Virtual Column

CREATE TABLE po_binaryxml OF XMLType
XMLTYPE STORE AS BINARY XML
VIRTUAL COLUMNS
(c_reference AS (XMLCast(XMLQuery('/PurchaseOrder/Reference'
PASSING OBJECT_VALUE RETURNING CONTENT)
AS VARCHAR2(32))));
INSERT INTO po_binaryxml SELECT OBJECT_VALUE FROM OE.purchaseorder;
132 rows created.
ALTER TABLE po_binaryxml ADD CONSTRAINT reference_is_unique UNIQUE (c_reference);
INSERT INTO po_binaryxml
VALUES (XMLType(bfilename('XMLDIR', 'DuplicateReference.xml'),
nls_charset_id('AL32UTF8')));
INSERT INTO po_binaryxml
*
ERROR at line 1:
ORA-00001: unique constraint (OE.REFERENCE_IS_UNIQUE) violated

Example 3–21 defines a uniqueness constraint similar to that of Example 3–20, but on
XMLType table purchaseorder in standard database schema OE. In addition, it
defines a foreign-key constraint that requires the User element of each purchase-order
document to be the e-mail address of an employee that is in standard database table
HR.employees. For XML data that is stored object-relationally, such as that in table
OE.purchaseorder, constraints must be specified in terms of object attributes of the
SQL data types that are used to manage the XML content.
Example 3–21 Integrity Constraints and Triggers for an XMLType Table Stored
Object-Relationally
ALTER TABLE purchaseorder
ADD CONSTRAINT reference_is_unique
UNIQUE (XMLDATA."REFERENCE");
ALTER TABLE purchaseorder
ADD CONSTRAINT user_is_valid
FOREIGN KEY (XMLDATA."USERID") REFERENCES hr.employees(email);
INSERT INTO purchaseorder
VALUES (XMLType(bfilename('XMLDIR', 'purchaseOrder.xml'),
nls_charset_id('AL32UTF8')));

Using Oracle XML DB 3-35

Enforcing XML Data Integrity using the Database

INSERT INTO purchaseorder
VALUES (XMLType(bfilename('XMLDIR', 'DuplicateReference.xml'),
nls_charset_id('AL32UTF8')));
INSERT INTO purchaseorder
*
ERROR at line 1:
ORA-00001: unique constraint (QUINE.REFERENCE_IS_UNIQUE) violated
INSERT INTO purchaseorder
VALUES (XMLType(bfilename('XMLDIR', 'InvalidUser.xml'),
nls_charset_id('AL32UTF8')));
INSERT INTO purchaseorder
*
ERROR at line 1:
ORA-02291: integrity constraint (QUINE.USER_IS_VALID) violated - parent key not
found

Just as for Example 3–20, the uniqueness constraint reference_is_unique of
Example 3–21 ensures the uniqueness of the purchase-order Reference element
across all documents stored in the table. The foreign key constraint user_is_valid
here ensures that the value of element User corresponds to a value in column email
of table employees.
The text node associated with the Reference element in the XML document
DuplicateRefernce.xml contains the same value as the corresponding node in
XML document PurchaseOrder.xml. Attempting to store both documents in Oracle
XML DB thus violates the constraint reference_is_unique.
The text node associated with the User element in XML document
InvalidUser.xml contains the value HACKER. There is no entry in the employees
table where the value of column email is HACKER. Attempting to store this document
in Oracle XML DB violates the constraint user_is_valid.
Integrity rules defined using constraints and triggers are also enforced when XML
schema-based XML content is loaded into Oracle XML DB Repository. Example 3–22
illustrates this. It shows that database integrity is also enforced when a protocol, such
as FTP, is used to upload XML schema-based XML content into Oracle XML DB
Repository.
Example 3–22

Enforcing Database Integrity When Loading XML using FTP

$ ftp localhost 2100
Connected to localhost.
220 mdrake-sun FTP Server (Oracle XML DB/Oracle Database 10g Enterprise Edition
Release 10.1.0.0.0 - Beta) ready.
Name (localhost:oracle10): QUINE
331 Password required for QUINE
Password: password
230 QUINE logged in
ftp> cd /source/schemas
250 CWD Command successful
ftp> put InvalidReference.xml
200 PORT Command successful
150 ASCII Data Connection
550- Error Response
ORA-00604: error occurred at recursive SQL level 1
ORA-31154: invalid XML document
ORA-19202: Error occurred in XML processing

3-36 Oracle XML DB Developer's Guide

DML Operations on XML Content using Oracle XML DB

LSX-00221: "SBELL-20021009" is too short (minimum length is 18)
ORA-06512: at "SYS.XMLTYPE", line 333
ORA-06512: at "QUINE.VALIDATE_PURCHASEORDER", line 3
ORA-04088: error during execution of trigger 'QUINE.VALIDATE_PURCHASEORDER'
550 End Error Response
ftp> put InvalidElement.xml
200 PORT Command successful
150 ASCII Data Connection
550- Error Response
ORA-30937: No schema definition for 'UserName' (namespace '##local') in parent
'PurchaseOrder'
550 End Error Response
ftp> put DuplicateReference.xml
200 PORT Command successful
150 ASCII Data Connection
550- Error Response
ORA-00604: error occurred at recursive SQL level 1
ORA-00001: unique constraint (QUINE.REFERENCE_IS_UNIQUE) violated
550 End Error Response
ftp> put InvalidUser.xml
200 PORT Command successful
150 ASCII Data Connection
550- Error Response
ORA-00604: error occurred at recursive SQL level 1
ORA-02291: integrity constraint (QUINE.USER_IS_VALID) violated - parent key not
found
550 End Error Response

When an error occurs while a document is being uploaded with a protocol, Oracle
XML DB provides the client with the full SQL error trace. How the error is interpreted
and reported to you is determined by the error-handling built into the client
application. Some clients, such as the command line FTP tool, reports the error
returned by Oracle XML DB, while others, such as Microsoft Windows Explorer, report
a generic error message.
See also:
■

■

"Specifying Relational Constraints on XMLType Tables and Columns"
on page 7-34
Oracle Database Error Messages

DML Operations on XML Content using Oracle XML DB
Another major advantage of using Oracle XML DB to manage XML content is that it
leverages the power of Oracle Database to deliver powerful, flexible capabilities for
querying and updating XML content, including the following:
■

Retrieving nodes and fragments within an XML document

■

Updating nodes and fragments within an XML document

■

Creating indexes on specific nodes within an XML document

■

Indexing the entire content of an XML document

■

Determining whether an XML document contains a particular node

XPath and Oracle XML
Oracle XML DB includes XMLType methods and XML-specific SQL functions. With
these, you can query and update XML content stored in Oracle Database. They use the
Using Oracle XML DB 3-37

Querying XML Content Stored in Oracle XML DB

W3C XPath Recommendation to identify the required node or nodes. Each node in an
XML document can be uniquely identified by an XPath expression.
An XPath expression consists of a slash-separated list of element names, attributes
names, and XPath functions. XPath expressions can contain positions and conditions
that determine which branch of the tree is traversed in determining the target nodes.
By supporting XPath-based methods and functions, Oracle XML DB makes it possible
for XML programmers to query and update XML documents in a familiar,
standards-compliant manner.
Oracle SQL functions and XMLType methods respect the W3C
XPath recommendation, which states that if an XPath expression
targets no nodes when applied to XML data, then an empty sequence
must be returned. An error must not be raised in this case.

Note:

The specific semantics of an Oracle SQL function or XMLType method
that applies an XPath expression to XML data determines what is
returned. For example, SQL/XML function XMLQuery returns NULL if
its XPath-expression argument targets no nodes, and the updating
SQL functions, such as deleteXML, return the input XML data
unchanged. An error is never raised if no nodes are targeted, but
updating SQL functions can raise an error if an XPath-expression
argument targets inappropriate nodes, such as attribute nodes or text
nodes.

Querying XML Content Stored in Oracle XML DB
This section describes techniques for querying Oracle XML DB and retrieving XML
content. This section contains these topics:
■
■

PurchaseOrder XML Document
Retrieving the Content of an XML Document using Pseudocolumn OBJECT_
VALUE

■

Accessing Fragments or Nodes of an XML Document using XMLQUERY

■

Accessing Text Nodes and Attribute Values using XMLCAST and XMLQUERY

■

Searching an XML Document using XMLEXISTS, XMLCast, and XMLQuery

■

Performing SQL Operations on XMLType Fragments using XMLTABLE

PurchaseOrder XML Document
Examples in this section are based on the PurchaseOrder XML document shown in
Example 3–23.
Example 3–23

PurchaseOrder XML Instance Document


SBELL-2002100912333601PDT


SVOLLMAN


3-38 Oracle XML DB Developer's Guide

Querying XML Content Stored in Oracle XML DB



Sarah J. Bell
SBELL
S30

Sarah J. Bell
400 Oracle Parkway
Redwood Shores
CA
94065
USA
650 506 7400

Air Mail


A Night to Remember



The Unbearable Lightness Of Being



Sisters





Retrieving the Content of an XML Document using Pseudocolumn OBJECT_VALUE
Pseudocolumn OBJECT_VALUE can be used as an alias for the value of an object table.
For an XMLType table that consists of a single column of XMLType, the entire XML
document is retrieved. (OBJECT_VALUE replaces the value(x) and SYS_NC_
ROWINFO$ aliases used in releases prior to Oracle Database10g Release 1.)
In Example 3–24, the SQL*Plus settings PAGESIZE and LONG are used to ensure that
the entire document is printed correctly, without line breaks. (The output has been
formatted for readability.)
Example 3–24

Retrieving an Entire XML Document using OBJECT_VALUE

SET LONG 10000
SET PAGESIZE 100
SELECT OBJECT_VALUE FROM purchaseorder;
OBJECT_VALUE
----------------------------------------------------------------------
SBELL-2002100912333601PDT


SVOLLMAN



Using Oracle XML DB 3-39

Querying XML Content Stored in Oracle XML DB


Sarah J. Bell
SBELL
S30

Sarah J. Bell
400 Oracle Parkway
Redwood Shores
CA
94065
USA
650 506 7400

Air Mail


A Night to Remember



The Unbearable Lightness Of Being



Sisters




1 row selected.

Accessing Fragments or Nodes of an XML Document using XMLQUERY
You can use SQL/XML function XMLQuery to extract the nodes that match an XPath
expression. The result is returned as an instance of XMLType. Example 3–25 illustrates
this with several queries.
Example 3–25

Accessing XML Fragments using XMLQUERY

The following query returns an XMLType instance containing the Reference element
that matches the XPath expression.
SELECT XMLQuery('/PurchaseOrder/Reference' PASSING OBJECT_VALUE RETURNING CONTENT)
FROM purchaseorder;
XMLQUERY('/PURCHASEORDER/REFERENCE'PASSINGOBJECT_
------------------------------------------------SBELL-2002100912333601PDT
1 row selected.

The following query returns an XMLType instance containing the first LineItem
element in the LineItems collection:
SELECT XMLQuery('/PurchaseOrder/LineItems/LineItem[1]'
PASSING OBJECT_VALUE RETURNING CONTENT)
FROM purchaseorder;
XMLQUERY('/PURCHASEORDER/LINEITEMS/LINEITEM[1]'PASSINGOBJECT_

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Querying XML Content Stored in Oracle XML DB

------------------------------------------------------------
A Night to Remember


1 row selected.

The following query returns an XMLType instance that contains the three
Description elements that match the XPath expression. These elements are returned
as nodes in a single XMLType instance. The XMLType instance does not have a single
root node; it is an XML fragment.
SELECT XMLQuery('/PurchaseOrder/LineItems/LineItem/Description'
PASSING OBJECT_VALUE RETURNING CONTENT)
FROM purchaseorder;
XMLQUERY('/PURCHASEORDER/LINEITEMS/LINEITEM/DESCRIPTION'PASSINGOBJECT_
---------------------------------------------------------------------A Night to Remember
The Unbearable Lightness Of Being
Sisters
1 row selected.

See Also: "Performing SQL Operations on XMLType Fragments
using XMLTABLE" on page 3-45

Accessing Text Nodes and Attribute Values using XMLCAST and XMLQUERY
You can access text node and attribute values using SQL/XML standard functions
XMLQuery and XMLCast. To do this, the XPath expression passed to XMLQuery must
uniquely identify a single text node or attribute value within the document – that is, a
leaf node. Example 3–26 illustrates this using several queries.
Example 3–26

Accessing a Text Node Value using XMLCAST and XMLQuery

The following query returns the value of the text node associated with the Reference
element that matches the target XPath expression. The value is returned as a
VARCHAR2 value.
SELECT

XMLCast(XMLQuery('$p/PurchaseOrder/Reference/text()'
PASSING OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(30))
FROM purchaseorder;

XMLCAST(XMLQUERY('$P/PURCHASEO
-----------------------------SBELL-2002100912333601PDT
1 row selected.

The following query returns the value of the text node associated with a
Description element contained in a LineItem element. The particular LineItem
element is specified by its Id attribute value. The predicate that identifies the
LineItem element is [Part/@Id="715515011020"]. The at-sign character (@)
specifies that Id is an attribute rather than an element. The value is returned as a
VARCHAR2 value.
SELECT XMLCast(

Using Oracle XML DB 3-41

Querying XML Content Stored in Oracle XML DB

XMLQuery('$p/PurchaseOrder/LineItems/LineItem[Part/@Id="715515011020"]/Description/text()'
PASSING OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(30))
FROM purchaseorder;
XMLCAST(XMLQUERY('$P/PURCHASEO
-----------------------------Sisters
1 row selected.

The following query returns the value of the text node associated with the
Description element contained in the first LineItem element. The first LineItem
element is indicated by the position predicate[1].
SELECT XMLCast(XMLQuery('$p/PurchaseOrder/LineItems/LineItem[1]/Description'
PASSING OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(4000))
FROM purchaseorder;
XMLCAST(XMLQUERY('$P/PURCHASEORDER/LINEITEMS/LINEITEM[1]/DESCRIPTION'PASSINGOBJECT_VALUEAS"P"
--------------------------------------------------------------------------------------------A Night to Remember
1 row selected.

See Also:
■

■

"Querying XMLType Data using SQL/XML Functions XMLExists
and XMLCast" on page 4-2 for information on SQL/XML function
XMLCast
Chapter 5, "Using XQuery with Oracle XML DB" for information
on SQL/XML function XMLQuery

Searching an XML Document using XMLEXISTS, XMLCast, and XMLQuery
SQL/XML standard function XMLExists evaluates whether or not a given document
contains a node that matches a W3C XPath expression. Function XMLExists returns a
Boolean value of true if the document contains the node specified by the XPath
expression supplied to the function and a value of false if it does not. Since XPath
expressions can contain predicates, XMLExists can determine whether or not a given
node exists in the document, and whether or not a node with the specified value exists
in the document.
Similarly, you can use SQL/XML functions XMLCast and XMLQuery in a SQL WHERE
clause to limit the query results to documents that satisfy some property.
Example 3–27 illustrates the use of XMLExists, XMLCast, and XMLQuery to search
for documents.
Example 3–27

Searching XML Content using XMLExists, XMLCast, and XMLQuery

The following query uses XMLExists to check if the XML document contains an
element named Reference that is a child of the root element PurchaseOrder:
SELECT count(*) FROM purchaseorder
WHERE XMLExists('$p/PurchaseOrder/Reference' PASSING OBJECT_VALUE AS "p");
COUNT(*)
---------132

3-42 Oracle XML DB Developer's Guide

Querying XML Content Stored in Oracle XML DB

1 row selected.

The following query checks if the value of the text node associated with the
Reference element is SBELL-2002100912333601PDT:
SELECT count(*) FROM purchaseorder
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
COUNT(*)
---------1
1 row selected.

This query checks whether the value of the text node associated with the Reference
element is SBELL-XXXXXXXXXXXXXXXXXX:
SELECT count(*) FROM purchaseorder
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-XXXXXXXXXXXXXXXXXX"]'
PASSING OBJECT_VALUE AS "p");
COUNT(*)
---------0
1 row selected.

This query checks whether the XML document contains a root element
PurchaseOrder that contains a LineItems element that contains a LineItem
element that contains a Part element with an Id attribute.
SELECT count(*) FROM purchaseorder
WHERE XMLExists('$p/PurchaseOrder/LineItems/LineItem/Part/@Id'
PASSING OBJECT_VALUE AS "p");
COUNT(*)
---------132
1 row selected.

The following query checks whether the XML document contains a root element
PurchaseOrder that contains a LineItems element that contains a LineItem
element that contains a Part element with Id attribute value 715515009058.
SELECT count(*) FROM purchaseorder
WHERE XMLExists('$p/PurchaseOrder/LineItems/LineItem/Part[@Id="715515009058"]'
PASSING OBJECT_VALUE AS "p");
COUNT(*)
---------21

The following query checks whether the XML document contains a root element
PurchaseOrder that contains a LineItems element whose third LineItem element
contains a Part element with Id attribute value 715515009058.
SELECT count(*) FROM purchaseorder
WHERE XMLExists(
'$p/PurchaseOrder/LineItems/LineItem[3]/Part[@Id="715515009058"]'

Using Oracle XML DB 3-43

Querying XML Content Stored in Oracle XML DB

PASSING OBJECT_VALUE AS "p");
COUNT(*)
---------1
1 row selected.

The following query limits the results of the SELECT statement to rows where the text
node associated with element User starts with the letter S. XQuery does not include
support for LIKE-based queries.
SELECT XMLCast(XMLQuery('$p/PurchaseOrder/Reference' PASSING OBJECT_VALUE AS "p"
RETURNING CONTENT)
AS VARCHAR2(30))
FROM purchaseorder
WHERE XMLCast(XMLQuery('$p/PurchaseOrder/User' PASSING OBJECT_VALUE AS "p"
RETURNING CONTENT)
AS VARCHAR2(30))
LIKE 'S%';
XMLCAST(XMLQUERY('$P/PURCHASEORDER
---------------------------------SBELL-20021009123336231PDT
SBELL-20021009123336331PDT
SKING-20021009123336321PDT
...
36 rows selected.

The following query performs a join based on the values of a node in an XML
document and data in another table.
SELECT XMLCast(XMLQuery('$p/PurchaseOrder/Reference' PASSING OBJECT_VALUE AS "p"
RETURNING CONTENT)
AS VARCHAR2(30))
FROM purchaseorder p, hr.employees e
WHERE XMLCast(XMLQuery('$p/PurchaseOrder/User' PASSING OBJECT_VALUE AS "p"
RETURNING CONTENT)
AS VARCHAR2(30)) = e.email
AND e.employee_id = 100;
XMLCAST(XMLQUERY('$P/PURCHASEOREDER
----------------------------------SKING-20021009123336321PDT
SKING-20021009123337153PDT
SKING-20021009123335560PDT
SKING-20021009123336952PDT
SKING-20021009123336622PDT
SKING-20021009123336822PDT
SKING-20021009123336131PDT
SKING-20021009123336392PDT
SKING-20021009123337974PDT
SKING-20021009123338294PDT
SKING-20021009123337703PDT
SKING-20021009123337383PDT
SKING-20021009123337503PDT
13 rows selected.

The following query uses XMLExists to limit the results of a SELECT statement to
rows where the text node of element User contains the value SBELL.

3-44 Oracle XML DB Developer's Guide

Querying XML Content Stored in Oracle XML DB

SELECT XMLCast(XMLQuery('$p/PurchaseOrder/Reference' PASSING OBJECT_VALUE AS "p"
RETURNING CONTENT)
AS VARCHAR2(30)) "Reference"
FROM purchaseorder
WHERE XMLExists('$p/PurchaseOrder[User="SBELL"]' PASSING OBJECT_VALUE AS "p");
Reference
-----------------------------SBELL-20021009123336231PDT
SBELL-20021009123336331PDT
SBELL-20021009123337353PDT
SBELL-20021009123338304PDT
SBELL-20021009123338505PDT
SBELL-20021009123335771PDT
SBELL-20021009123335280PDT
SBELL-2002100912333763PDT
SBELL-2002100912333601PDT
SBELL-20021009123336362PDT
SBELL-20021009123336532PDT
SBELL-20021009123338204PDT
SBELL-20021009123337673PDT
13 rows selected.

Example 3–28 uses SQL/XML functions XMLQuery and XMLExists to find the
Reference element for any PurchaseOrder element whose first LineItem element
contains an order for the item with Id 715515009058. Function XMLExists is used
in the WHERE clause to determine which rows are selected, and XMLQuery is used in
the SELECT list to control which part of the selected documents appears in the result.
Example 3–28

Finding the Reference for a Purchase Order using XMLQuery and XMLExists

SELECT XMLCast(XMLQuery('$p/PurchaseOrder/Reference' PASSING OBJECT_VALUE AS "p"
RETURNING CONTENT)
AS VARCHAR2(30)) "Reference"
FROM purchaseorder
WHERE XMLExists('$p/PurchaseOrder/LineItems/LineItem[1]/Part[@Id="715515009058"]'
PASSING OBJECT_VALUE AS "p");
Reference
------------------------SBELL-2002100912333601PDT
1 row selected.

See Also:
■

■

"Querying XMLType Data using SQL/XML Functions XMLExists
and XMLCast" on page 4-2 for information on SQL/XML
functions XMLCast and XMLExists
Chapter 5, "Using XQuery with Oracle XML DB" for information
on SQL/XML function XMLQuery

Performing SQL Operations on XMLType Fragments using XMLTABLE
Example 3–25 demonstrates how to extract an XMLType instance that contains the
node or nodes that match an XPath expression. When the document contains multiple
nodes that match the supplied XPath expression, such a query returns an XML

Using Oracle XML DB 3-45

Querying XML Content Stored in Oracle XML DB

fragment that contains all of the matching nodes. Unlike an XML document, an XML
fragment has no single element that is the root element.
This kind of result is common in these cases:
■

■

When you retrieve the set of elements contained in a collection, in which case all
nodes in the fragment are of the same type – see Example 3–29
When the target XPath expression ends in a wildcard, in which case the nodes in
the fragment can be of different types – see Example 3–31

You can use SQL/XML function XMLTable to break up an XML fragment contained in
an XMLType instance, inserting the collection-element data into a new, virtual table,
which you can then query using SQL—in a join expression, for example. In particular,
converting an XML fragment into a virtual table makes it easier to process the result of
evaluating an XMLQuery expression that returns multiple nodes.
Example 3–29 shows how to access the text nodes for each Description element in
the PurchaseOrder document. It breaks up the single XML Fragment output from
Example 3–25 into multiple text nodes.
Example 3–29

Accessing Description Nodes using XMLTABLE

SELECT des.COLUMN_VALUE
FROM purchaseorder p,
XMLTable('/PurchaseOrder/LineItems/LineItem/Description'
PASSING p.OBJECT_VALUE) des
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
COLUMN_VALUE
-----------A Night to Remember
The Unbearable Lightness Of Being
Sisters
3 rows selected.

To use SQL to process the contents of the text nodes, Example 3–29 converts the
collection of Description nodes into a virtual table, using SQL/XML function
XMLTable. The virtual table has three rows, each of which contains a single XMLType
instance with a single Description element.
The XPath expression targets the Description elements. The PASSING clause says to
use the contents (OBJECT_VALUE) of XMLType table purchaseorder as the context
for evaluating the XPath expression.
The XMLTable expression thus depends on the purchaseorder table. This is a left
lateral join. This correlated join ensures a one-to-many (1:N) relationship between the
purchaseorder row accessed and the rows generated from it by XMLTable. Because
of this correlated join, the purchaseorder table must appear before the XMLTable
expression in the FROM list. This is a general requirement in any situation where the
PASSING clause refers to a column of the table.
Each XMLType instance in the virtual table contains a single Description element.
You can use the COLUMNS clause of XMLTable to break up the data targeted by the
XPath expression 'Description' into a column named description of SQL data
type VARCHAR2(256). The 'Description' expression that defines this column is
relative to the context XPath expression,
'/PurchaseOrder/LineItems/LineItem'.

3-46 Oracle XML DB Developer's Guide

Querying XML Content Stored in Oracle XML DB

SELECT des.description
FROM purchaseorder p,
XMLTable('/PurchaseOrder/LineItems/LineItem' PASSING p.OBJECT_VALUE
COLUMNS description VARCHAR2(256) PATH 'Description') des
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
DESCRIPTION
--------------------------------A Night to Remember
The Unbearable Lightness Of Being
Sisters
3 rows selected.

The COLUMNS clause lets you specify precise SQL data types, which can make static
type-checking more helpful. This example uses only a single column (description).
To expose data that is contained at multiple levels in an XMLType table as individual
rows in a relational view, apply XMLTable to each document level to be broken up
and stored in relational columns. See Example 3–33 for an example.
Example 3–30 counts the number of elements in a collection. It also shows how SQL
keywords such as ORDER BY and GROUP BY can be applied to the virtual table data
created by SQL/XML function XMLTable.
Example 3–30

Counting the Number of Elements in a Collection using XMLTABLE

SELECT reference, count(*)
FROM purchaseorder,
XMLTable('/PurchaseOrder' PASSING OBJECT_VALUE
COLUMNS reference VARCHAR2(32) PATH 'Reference',
lineitem XMLType
PATH 'LineItems/LineItem'),
XMLTable('LineItem' PASSING lineitem)
WHERE XMLExists('$p/PurchaseOrder[User="SBELL"]'
PASSING OBJECT_VALUE AS "p")
GROUP BY reference
ORDER BY reference;
REFERENCE
-------------------------SBELL-20021009123335280PDT
SBELL-20021009123335771PDT
SBELL-2002100912333601PDT
SBELL-20021009123336231PDT
SBELL-20021009123336331PDT
SBELL-20021009123336362PDT
SBELL-20021009123336532PDT
SBELL-20021009123337353PDT
SBELL-2002100912333763PDT
SBELL-20021009123337673PDT
SBELL-20021009123338204PDT
SBELL-20021009123338304PDT
SBELL-20021009123338505PDT

COUNT(*)
-------20
21
3
25
10
15
14
10
21
10
14
24
20

13 rows selected.

The query in Example 3–30 locates the set of XML documents that match the XPath
expression to SQL/XML function XMLExists. It generates a virtual table with two
columns:

Using Oracle XML DB 3-47

Accessing XML Data in Oracle XML DB using Relational Views

■

reference, containing the Reference node for each document selected

■

lineitem, containing the set of LineItem nodes for each document selected

It counts the number of LineItem nodes for each document. A correlated join ensures
that the GROUP BY correctly determines which LineItem elements belong to which
PurchaseOrder element.
Example 3–31 shows how to use SQL/XML function XMLTable to count the number
of child elements of a given element. The XPath expression passed to XMLTable
contains a wildcard (*) that matches all elements that are direct descendants of a
PurchaseOrder element. Each row of the virtual table created by XMLTable contains
a node that matches the XPath expression. Counting the number of rows in the virtual
table provides the number of element children of element PurchaseOrder.
Example 3–31

Counting the Number of Child Elements in an Element using XMLTABLE

SELECT count(*)
FROM purchaseorder p, XMLTable('/PurchaseOrder/*' PASSING p.OBJECT_VALUE)
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
COUNT(*)
---------9
1 row selected.

Accessing XML Data in Oracle XML DB using Relational Views
You can use the XML-specific functions and methods provided by Oracle XML DB to
create conventional relational views that provide relational access to XML content. This
lets programmers, tools, and applications that understand Oracle Database, but not
XML, to work with XML content stored in the database.
The relational views can use XPath expressions and SQL/XML query and access
functions such as XMLTable to define a mapping between columns in the view and
nodes in the XML document. For performance reasons, this approach is recommended
only when XML documents are stored using structured (object-relational) or binary
XML storage, not when stored as CLOB instances.
See Also:
■

■

■

■

Chapter 4, "XMLType Operations" for a description of XMLType
data type and functions
http://www.w3.org/TR/xpath for information about
XPath 1.0
http://www.w3.org/TR/xpath20/ for information about
XPath 2.0
http://www.w3.org/TR/2002/NOTE-unicode-xml-200202
18/ for information about using Unicode in XML

Breaking Up a Single Level of XML Data
When you need to expose each document in an XMLType table as a row in a relational
view, you can use this technique:

3-48 Oracle XML DB Developer's Guide

Accessing XML Data in Oracle XML DB using Relational Views

1.

Define the set of columns that make up the view, using CREATE OR REPLACE
VIEW.

2.

Map the nodes in the XML document to the columns defined by the view. You do
this by extracting the nodes using SQL/XML function XMLTable with
appropriate XPath expressions.

This technique can be used whenever there is a one-to-one (1:1) relationship between
documents in the XMLType table and the rows in the view.
Example 3–32 shows how to create a simple relational view, purchaseorder_
master_view, that exposes XML content. There is one row in the view for each row
in XMLType table purchaseorder.
Example 3–32

Creating a Relational View of XML Content

CREATE OR REPLACE VIEW purchaseorder_master_view AS
SELECT po.*
FROM purchaseorder pur,
XMLTable(
'$p/PurchaseOrder' PASSING pur.OBJECT_VALUE as "p"
COLUMNS
reference
VARCHAR2(30)
PATH 'Reference',
requestor
VARCHAR2(128) PATH 'Requestor',
userid
VARCHAR2(10)
PATH 'User',
costcenter
VARCHAR2(4)
PATH 'CostCenter',
ship_to_name
VARCHAR2(20)
PATH 'ShippingInstructions/name',
ship_to_address VARCHAR2(256) PATH 'ShippingInstructions/address',
ship_to_phone
VARCHAR2(24)
PATH 'ShippingInstructions/telephone',
instructions
VARCHAR2(2048) PATH 'SpecialInstructions') po;
View created.
DESCRIBE purchaseorder_master_view
Name
Null?
Type
-------------------------------------------REFERENCE
VARCHAR2(30)
REQUESTOR
VARCHAR2(128)
USERID
VARCHAR2(10)
COSTCENTER
VARCHAR2(4)
SHIP_TO_NAME
VARCHAR2(20)
SHIP_TO_ADDRESS
VARCHAR2(256)
SHIP_TO_PHONE
VARCHAR2(24)
INSTRUCTIONS
VARCHAR2(2048)

Breaking Up Multiple Levels of XML Data
When you need to expose data contained at multiple levels in an XMLType table as
individual rows in a relational view, you use the same general approach as for
breaking up a single level: 1) define the columns making up the view, and 2) map the
XML nodes to the columns. However, in this case you apply XMLTable, to each
document level that is to be broken up and stored in relational columns.
This technique can be used whenever there is a one-to-many (1:N) relationship
between documents in the XMLType table and the rows in the view.
For example, each PurchaseOrder element contains a LineItems element, which in
turn contains one or more LineItem elements. Each LineItem element has child
elements, such as Description, and an ItemNumber attribute. To make such
Using Oracle XML DB 3-49

Accessing XML Data in Oracle XML DB using Relational Views

lower-level data accessible as a relational value, you must break up both the
PurchaseOrder element and the LineItem collection. Each such decomposition is
done with XMLTable. When element PurchaseOrder is broken up, the LineItem
element is mapped to a relational column of type XMLType, which contains an XML
fragment. That column is then passed to the second call to XMLType, to be broken into
its various parts as multiple rows of relational values.
Example 3–33 illustrates this. It shows how to use SQL/XML function XMLTable for a
one-to-many (1:N) relationship between the documents in XMLType table
purchaseorder and the view rows. The view provides access to the individual
members of a collection, and exposes the collection members as a set of rows.
Example 3–33

Accessing Individual Members of a Collection using a View

CREATE OR REPLACE VIEW purchaseorder_detail_view AS
SELECT po.reference, li.*
FROM purchaseorder p,
XMLTable('/PurchaseOrder' PASSING p.OBJECT_VALUE
COLUMNS
reference VARCHAR2(30) PATH 'Reference',
lineitem XMLType
PATH 'LineItems/LineItem') po,
XMLTable('/LineItem' PASSING po.lineitem
COLUMNS
itemno
NUMBER(38)
PATH '@ItemNumber',
description VARCHAR2(256) PATH 'Description',
partno
VARCHAR2(14) PATH 'Part/@Id',
quantity
NUMBER(12, 2) PATH 'Part/@Quantity',
unitprice
NUMBER(8, 4) PATH 'Part/@UnitPrice') li;
View created.
DESCRIBE purchaseorder_detail_view
Name
Null?
Type
---------------------------REFERENCE
VARCHAR2(30)
ITEMNO
NUMBER(38)
DESCRIPTION
VARCHAR2(256)
PARTNO
VARCHAR2(14)
QUANTITY
NUMBER(12,2)
UNITPRICE
NUMBER(8,4)

In Example 3–33, there is one row in view purchaseorder_detail_view for each
LineItem element in the XML documents stored in XMLType table purchaseorder.
The CREATE OR REPLACE VIEW statement defines the set of columns that make up
the view. The SELECT statement passes the purchaseorder table as context to
function XMLTable, to create the virtual table p, which has columns reference and
lineitem. These columns contain the Reference and LineItem elements of the
purchase-order documents, respectively.
Column lineitem contains a collection of LineItem elements, as an XMLType
instance—one row for each LineItem element. These rows are in turn passed to a
second XMLTable expression, to serve as its context. This second XMLTable
expression creates a virtual table of line-item rows, with columns corresponding to
various descendant nodes of element LineItem. Most of these descendants are
attributes (ItemNumber, Part/@Id, and so on). One of the descendants is the
Description child element.
The Reference element is included in view purchaseorder_detail_view as
column reference. It provides a foreign key that can be used to joins rows in view
3-50 Oracle XML DB Developer's Guide

Accessing XML Data in Oracle XML DB using Relational Views

purchaseorder_detail_view to the corresponding row in view
purchaseorder_master_view. The correlated join in the CREATE VIEW statement
ensures that the one-to-many (1:N) relationship between the Reference element and
the associated LineItem elements is maintained whenever the view is accessed.

Querying XML Content As Relational Data
The examples in this section show relational queries of XML data. They point out some
of the benefits provided by creating relational views over XMLType tables and
columns.
Example 3–34 shows how to query master and detail relational views of XML data.
Example 3–34

Querying XML Data using Views

The following simple query against a master view uses a conventional SELECT
statement to return the rows where the userid column starts with S.
SELECT reference, costcenter, ship_to_name
FROM purchaseorder_master_view
WHERE userid LIKE 'S%';
REFERENCE
-----------------------------SBELL-20021009123336231PDT
SBELL-20021009123336331PDT
SKING-20021009123336321PDT
...
36 rows selected.

COST
---S30
S30
A10

SHIP_TO_NAME
-------------Sarah J. Bell
Sarah J. Bell
Steven A. King

The following query is based on a join between the master view and the detail view. A
conventional SELECT statement finds the purchaseorder_detail_view rows
where the value of column itemno is 1 and the corresponding purchaseorder_
master_view row contains a userid column with the value SBELL.
SELECT d.reference, d.itemno, d.partno, d.description
FROM purchaseorder_detail_view d, purchaseorder_master_view m
WHERE m.reference = d.reference
AND m.userid = 'SBELL'
AND d.itemno = 1;
REFERENCE
ITEMNO PARTNO
DESCRIPTION
------------------------------ -----------------------------------------------SBELL-20021009123336231PDT
1 37429165829
Juliet of the Spirits
SBELL-20021009123336331PDT
1 715515009225
Salo
SBELL-20021009123337353PDT
1 37429141625
The Third Man
SBELL-20021009123338304PDT
1 715515009829
Nanook of the North
SBELL-20021009123338505PDT
1 37429122228
The 400 Blows
SBELL-20021009123335771PDT
1 37429139028
And the Ship Sails on
SBELL-20021009123335280PDT
1 715515011426
All That Heaven Allows
SBELL-2002100912333763PDT
1 715515010320
Life of Brian - Python
SBELL-2002100912333601PDT
1 715515009058
A Night to Remember
SBELL-20021009123336362PDT
1 715515012928
In the Mood for Love
SBELL-20021009123336532PDT
1 37429162422
Wild Strawberries
SBELL-20021009123338204PDT
1 37429168820
Red Beard
SBELL-20021009123337673PDT
1 37429156322
Cries and Whispers
13 rows selected.

Using Oracle XML DB 3-51

Updating XML Content Stored in Oracle XML DB

The views in Example 3–34 look and act like standard relational views. They can be
queried using standard relational syntax. No XML-specific syntax is required in either
the query or the generated result set.
By exposing XML content as relational data, Oracle XML DB lets you apply advanced
database features, such as business intelligence and analytic capabilities, to XML
content, even if such features themselves are not XML-aware.
Example 3–35 shows how to use relational views over XML content to perform
business-intelligence queries on XML documents. The example query selects
PurchaseOrder documents that contain orders for titles identified by UPC codes
715515009058 and 715515009126.
Example 3–35

Business-Intelligence Query of XML Data using a View

SELECT partno, count(*) "No of Orders", quantity "No of Copies"
FROM purchaseorder_detail_view
WHERE partno IN (715515009126, 715515009058)
GROUP BY rollup(partno, quantity);
PARTNO
No of Orders No of Copies
-------------- ------------ -----------715515009058
7
1
715515009058
9
2
715515009058
5
3
715515009058
2
4
715515009058
23
715515009126
4
1
715515009126
7
3
715515009126
11
34
9 rows selected.

The query in Example 3–35 determines the number of copies of each title that are
ordered in each PurchaseOrder document. For part number 715515009126, there
are four PurchaseOrder documents where one copy of the item is ordered and seven
PurchaseOrder documents where three copies of the item are ordered.

Updating XML Content Stored in Oracle XML DB
Oracle XML DB lets update operations take place on XML content. Update operations
can either replace the entire contents of a document or parts of a document. The ability
to perform partial updates on XML documents is very powerful, particularly when
you make small changes to large documents, as it can significantly reduce the amount
of network traffic and disk input-output required to perform the update.
SQL function updateXML enables partial update of an XML document stored as an
XMLType instance. It lets multiple changes be made to the document in a single
operation. Each change consists of an XPath expression that identifies a node to be
updated, and the new value for the node.
Example 3–36 uses SQL function updateXML to update the text node associated with
element User.
Example 3–36

Updating XML Content using UPDATEXML

SELECT XMLCast(XMLQuery('$p/PurchaseOrder/User' PASSING OBJECT_VALUE AS "p"
RETURNING CONTENT)
AS VARCHAR2(60))
FROM purchaseorder
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Updating XML Content Stored in Oracle XML DB

WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
XMLCAST(XMLQUERY('$P/PURCHAS
---------------------------SBELL
1 row selected.
UPDATE purchaseorder
SET OBJECT_VALUE =
updateXML(OBJECT_VALUE, '/PurchaseOrder/User/text()', 'SKING')
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
1 row updated.
SELECT XMLCast(XMLQuery('$p/PurchaseOrder/User' PASSING OBJECT_VALUE AS "p"
RETURNING CONTENT)
AS VARCHAR2(60))
FROM purchaseorder
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
XMLCAST(XMLQUERY('$P/PURCHAS
---------------------------SKING
1 row selected.

Example 3–37 uses SQL function updateXML to replace an entire element within an
XML document. The XPath expression references the element, and the replacement
value is passed as an XMLType object.
Example 3–37

Replacing an Entire Element using UPDATEXML

SELECT XMLQuery('$p/PurchaseOrder/LineItems/LineItem[1]'
PASSING OBJECT_VALUE AS "p" RETURNING CONTENT)
FROM purchaseorder
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
XMLQUERY('$P/PURCHAS
-------------------
A Night to Remember


1 row selected.
UPDATE purchaseorder
SET OBJECT_VALUE =
updateXML(
OBJECT_VALUE,
'/PurchaseOrder/LineItems/LineItem[1]',
XMLType('
The Lady Vanishes

'))

Using Oracle XML DB 3-53

Updating XML Content Stored in Oracle XML DB

WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
1 row updated.
SELECT XMLQuery('$p/PurchaseOrder/LineItems/LineItem[1]'
PASSING OBJECT_VALUE AS "p" RETURNING CONTENT)
FROM purchaseorder
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
XMLQUERY('$P/PURCHAS
-------------------
The Lady Vanishes


1 row selected.

Example 3–38 illustrates the common mistake of using SQL function updateXML to
update a node that occurs multiple times in a collection. The UPDATE statement sets the
value of the text node of a Description element to The Wizard of Oz, where the
current value of the text node is Sisters. The statement includes an XMLExists
expression in the WHERE clause that identifies the set of nodes to be updated.
Example 3–38

Incorrectly Updating a Node That Occurs Multiple Times in a Collection

SELECT XMLCast(des.COLUMN_VALUE AS VARCHAR2(256))
FROM purchaseorder,
XMLTable('$p/PurchaseOrder/LineItems/LineItem/Description'
PASSING OBJECT_VALUE AS "p") des
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
XMLCAST(DES.COLUMN_VALUEASVARCHAR2(256))
---------------------------------------The Lady Vanishes
The Unbearable Lightness Of Being
Sisters
3 rows selected.
UPDATE purchaseorder p
SET p.OBJECT_VALUE =
updateXML(p.OBJECT_VALUE,
'/PurchaseOrder/LineItems/LineItem/Description/text()',
'The Wizard of Oz')
WHERE XMLExists('$p/PurchaseOrder/LineItems/LineItem[Description="Sisters"]'
PASSING OBJECT_VALUE AS "p")
AND XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
1 row updated.
SELECT XMLCast(des.COLUMN_VALUE AS VARCHAR2(256))
FROM purchaseorder,
XMLTable('$p/PurchaseOrder/LineItems/LineItem/Description'
PASSING OBJECT_VALUE AS "p") des
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'

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Updating XML Content Stored in Oracle XML DB

PASSING OBJECT_VALUE AS "p");
XMLCAST(DES.COLUMN_VALUEASVARCHAR2(256))
---------------------------------------The Wizard of Oz
The Wizard of Oz
The Wizard of Oz
3 rows selected.

In Example 3–38, instead of updating only the intended node, SQL function
updateXML updates the values of all text nodes that belong to the Description
element. This is the correct updateXML behavior, but it is not what was intended.
A WHERE clause can be used only to identify which documents must be updated, not which
nodes within a document must be updated.
After the document has been selected, the XPath expression passed to updateXML
determines which nodes within the document must be updated. In this case, the XPath
expression identifies all three Description nodes, so all three of the associated text
nodes were updated.
To correctly use SQL function updateXML to update a node that occurs multiple times
within a collection, use the XPath expression passed to updateXML to identify which
nodes in the XML document to update. By introducing the appropriate predicate into
the XPath expression, you can limit which nodes in the document are updated.
Example 3–39 illustrates the correct way to update one node within a collection.
Example 3–39

Correctly Updating a Node That Occurs Multiple Times in a Collection

SELECT XMLCast(des.COLUMN_VALUE AS VARCHAR2(256))
FROM purchaseorder,
XMLTable('$p/PurchaseOrder/LineItems/LineItem/Description'
PASSING OBJECT_VALUE AS "p") des
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
XMLCAST(DES.COLUMN_VALUEASVARCHAR2(256))
---------------------------------------A Night to Remember
The Unbearable Lightness Of Being
Sisters
3 rows selected.
UPDATE purchaseorder p
SET p.OBJECT_VALUE =
updateXML(
p.OBJECT_VALUE,
'/PurchaseOrder/LineItems/LineItem/Description[text()="Sisters"]/text()',
'The Wizard of Oz')
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
1 row updated.
SELECT XMLCast(des.COLUMN_VALUE AS VARCHAR2(256))
FROM purchaseorder,
XMLTable('$p/PurchaseOrder/LineItems/LineItem/Description'
PASSING OBJECT_VALUE AS "p") des
Using Oracle XML DB 3-55

Updating XML Content Stored in Oracle XML DB

WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
XMLCAST(DES.COLUMN_VALUEASVARCHAR2(256))
---------------------------------------A Night to Remember
The Unbearable Lightness Of Being
The Wizard of Oz
3 rows selected.

SQL function updateXML lets multiple changes be made to the document in one
statement. Example 3–40 shows how to change the values of text nodes belonging to
the User and SpecialInstructions elements in one statement.
Example 3–40

Changing Text Node Values using UPDATEXML

SELECT XMLCast(XMLQuery('$p/PurchaseOrder/CostCenter'
PASSING OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(4)) "Cost Center",
XMLCast(XMLQuery('$p/PurchaseOrder/SpecialInstructions'
PASSING OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(2048)) "Instructions"
FROM purchaseorder
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
Cost Center Instructions
------------ -----------S30
Air Mail
1 row selected.

The following single UPDATE SQL statement changes the User and
SpecialInstructions element text node values:
UPDATE purchaseorder
SET OBJECT_VALUE =
updateXML(OBJECT_VALUE,
'/PurchaseOrder/CostCenter/text()',
'B40',
'/PurchaseOrder/SpecialInstructions/text()',
'Priority Overnight Service')
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
1 row updated.
SELECT XMLCast(XMLQuery('$p/PurchaseOrder/CostCenter'
PASSING OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(4)) "Cost Center",
XMLCast(XMLQuery('$p/PurchaseOrder/SpecialInstructions'
PASSING OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(2048)) "Instructions"
FROM purchaseorder
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
Cost Center Instructions
------------ --------------------------

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Namespace Support in Oracle XML DB

B40

Priority Overnight Service

1 row selected.

Updating XML Schema-Based and Non-Schema-Based XML Documents
The way SQL functions such as updateXML modify an XML document depends on
how the XML document is stored and whether it is based on an XML schema:
■

■

■

XML documents stored in CLOB values – When a SQL function such as
updateXML modifies an XML document stored as a CLOB (whether or not it is
XML schema-based), Oracle XML DB performs the update by creating a
Document Object Model (DOM) from the document and using DOM API methods
to modify the appropriate XML data. After modification, the updated DOM is
returned back to the underlying CLOB value.
XML documents stored object-relationally – When a SQL function such as
updateXML modifies an XML schema-based document that is stored
object-relationally, Oracle XML DB can use XPath rewrite to modify the
underlying objects in place. This is a partial update, which translates the XPath
argument to the SQL function into an equivalent SQL operation. The SQL
operation then directly modifies the attributes of underlying objects. Such a partial
update can be much quicker than a DOM-based update. This can improve
performance significantly when executing SQL code that applies a SQL function
such as updateXML to a large number of documents.
XML documents stored as binary XML – When a SQL function such as
updateXML is used on a binary XML column, Oracle XML DB often need not
build a DOM. The exact portion of the document that must be updated is
calculated using query evaluation techniques such as streaming and XMLIndex.
The updated data is written to disk starting only where the first change
occurs—anything before that is unchanged. In addition, if SecureFile LOBs are
used for storing the data (the default behavior), then the change is applied in a
sliding manner, without causing the rest of the LOB to be rewritten. That is, with
SecureFile LOB storage of binary XML data, only the data that is actually changed
is updated. This can significantly improve performance relative to unstructured
storage. These optimizations apply to both non-schema-based and XML
schema-based data.
See Also:

Chapter 8, "XPath Rewrite for Structured Storage"

Namespace Support in Oracle XML DB
Namespace support is a key feature of the W3C XML Recommendations. Oracle
XML DB fully supports the W3C Namespace Recommendation. All XMLType methods
and XML-specific SQL functions work with XPath expressions that include namespace
prefixes. All methods and functions accept an optional namespace argument that
provides the namespace declarations for correctly resolving namespace prefixes used
in XPath expressions.
The namespace parameter is required whenever the provided XPath expression
contains namespace prefixes. When parameter namespace is provided, it must
provide an explicit declaration for the default namespace in addition to the prefixed
namespaces, unless the default namespace is the noNamespace namespace. When
parameter namespace is not provided, Oracle XML DB makes the following
assumptions about the XPath expression:

Using Oracle XML DB 3-57

How Oracle XML DB Processes XMLType Methods and SQL Functions

■

■

If the content of the XMLType instance is not based on a registered XML schema,
then any term in the XPath expression that does include a namespace prefix is
assumed to be in the noNamespace namespace.
If the content of the XMLType is based on a registered XML schema, then any term
in the XPath expression that does not include a namespace prefix is assumed to be
in the targetNamespace declared by the XML schema, if any. If the XML schema
does not declare a targetnamespace, then names noNamespace is used.

Failing to correctly define the namespaces required to resolve XPath expressions
results in XPath-based operations not working as expected. When the namespace
declarations are incorrect or missing, the result of the operation is normally null, rather
than an error. To avoid confusion, whenever any namespaces other than
noNamespace are present in either the XPath expression or the target XML document,
pass the complete set of namespace declarations, including the declaration for the default
namespace.

How Oracle XML DB Processes XMLType Methods and SQL Functions
Oracle XML DB processes SQL/XML access and query functions such as XMLQuery
and XMLType methods using DOM-based or SQL-based techniques:
■

DOM-based XMLType processing – Oracle XML DB performs the required
processing by constructing a DOM from the contents of the XMLType object. It
uses methods provided by the DOM API to perform the required operation on the
DOM. If the operation involves updating the DOM tree, then the entire XML
document has to be written back to disk when the operation is completed. The
process of using DOM-based operations on XMLType data is referred to as
functional evaluation.
The advantage of functional evaluation is that it can be used regardless of the
storage model (structured, binary XML, or unstructured) used for the XMLType
instance. The disadvantage of functional evaluation is that it much more expensive
than XPath rewrite, and does not scale across large numbers of XML documents.

■

SQL-based XMLType processing – Oracle XML DB constructs a SQL statement that
performs the processing required to complete the function or method. The SQL
statement works directly against the object-relational data structures that underlie
a schema-based XMLType. This process is referred to as XPath rewrite. See
Chapter 8, "XPath Rewrite for Structured Storage".
The advantage of XPath rewrite is that it lets Oracle XML DB evaluate
XPath-based SQL functions and methods at near relational speeds. This lets these
operations scale across large numbers of XML documents. The disadvantage of XPath
rewrite is that since it relies on direct access and updating the objects used to store
the XML document, it can be used only when the XMLType instance is stored
using XML schema-based object-relational storage techniques.

■

Streaming evaluation of binary XML data – If you use binary XML as the XMLType
storage model, then XPath expressions used in SQL/XML access and query
functions such as XMLQuery are evaluated in a streaming fashion, without
recourse to building a DOM.

Generating XML Data from Relational Data
This section presents examples of using Oracle XML DB to generate XML data from
relational data.

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Generating XML Data from Relational Data

See Also:
■

Chapter 5, "Using XQuery with Oracle XML DB"

■

Chapter 18, "Generating XML Data from the Database"

Generating XML Data from Relational Data using SQL/XML Functions
You can use standard SQL/XML functions to generate one or more XML documents.
SQL/XML function XMLQuery is the most general way to do this. Other SQL/XML
functions that you can use for this are the following:
■

XMLElement creates a element

■

XMLAttributes adds attributes to an element

■

XMLForest creates forest of elements

■

XMLAgg creates a single element from a collection of elements

The query in Example 3–41 uses these functions to generate an XML document that
contains information from the tables departments, locations, countries,
employees, and jobs.
Example 3–41

Generating XML Data using SQL/XML Functions

SELECT XMLElement(
"Department",
XMLAttributes(d.Department_id AS "DepartmentId"),
XMLForest(d.department_name AS "Name"),
XMLElement(
"Location",
XMLForest(street_address AS "Address",
city AS "City",
state_province AS "State",
postal_code AS "Zip",
country_name AS "Country")),
XMLElement(
"EmployeeList",
(SELECT XMLAgg(
XMLElement(
"Employee",
XMLAttributes(e.employee_id AS "employeeNumber"),
XMLForest(
e.first_name AS "FirstName",
e.last_name AS "LastName",
e.email AS "EmailAddress",
e.phone_number AS "PHONE_NUMBER",
e.hire_date AS "StartDate",
j.job_title AS "JobTitle",
e.salary AS "Salary",
m.first_name || ' ' || m.last_name AS "Manager"),
XMLElement("Commission", e.commission_pct)))
FROM hr.employees e, hr.employees m, hr.jobs j
WHERE e.department_id = d.department_id
AND j.job_id = e.job_id
AND m.employee_id = e.manager_id)))
AS XML
FROM hr.departments d, hr.countries c, hr.locations l
WHERE department_name = 'Executive'
AND d.location_id = l.location_id
AND l.country_id = c.country_id;

Using Oracle XML DB 3-59

Generating XML Data from Relational Data

The query returns the following XML:
XML
-------------------------------------------------------------------------------Executive
2004
Charade Rd
SeattleWashingto
n98199United States of
AmericaNeenaKochharNKOCHHAR515.123.45682005-09-21Administration Vice
President17000Steven KingLexDe
HaanL
DEHAAN515.123.45692001-01-13Administration Vice Presiden
t17000Steven
King

This query generates element Department for each row in the departments table.
■

■

■

■

Each Department element contains attribute DepartmentID. The value of
DepartmentID comes from the department_id column. The Department
element contains sub-elements Name, Location, and EmployeeList.
The text node associated with the Name element comes from the name column in
the departments table.
The Location element has child elements Address, City, State, Zip, and
Country. These elements are constructed by creating a forest of named elements
from columns in the locations and countries tables. The values in the
columns become the text node for the named element.
The EmployeeList element contains an aggregation of Employee Elements. The
content of the EmployeeList element is created by a subquery that returns the
set of rows in the employees table that correspond to the current department.
Each Employee element contains information about the employee. The contents
of the elements and attributes for each Employee element is taken from tables
employees and jobs.

The output generated by SQL/XML functions is generally not pretty-printed. The only
exception is function XMLSerialize—use XMLSerialize to pretty-print. This lets
the other SQL/XML functions (1) avoid creating a full DOM when generating the
required output, and (2) reduce the size of the generated document. This lack of
pretty-printing by most SQL/XML functions does not matter to most applications.
However, it makes verifying the generated output manually more difficult.
Example 3–42

Creating XMLType Views Over Conventional Relational Tables

CREATE OR REPLACE VIEW department_xml OF XMLType
WITH OBJECT ID (substr(
XMLCast(
XMLQuery('$p/Department/Name'
PASSING OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(30)),
1,
128))
AS

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Generating XML Data from Relational Data

SELECT XMLElement(
"Department",
XMLAttributes(d.department_id AS "DepartmentId"),
XMLForest(d.department_name AS "Name"),
XMLElement("Location", XMLForest(street_address AS "Address",
city AS "City",
state_province AS "State",
postal_code AS "Zip",
country_name AS "Country")),
XMLElement(
"EmployeeList",
(SELECT XMLAgg(
XMLElement(
"Employee",
XMLAttributes(e.employee_id AS "employeeNumber"),
XMLForest(e.first_name AS "FirstName",
e.last_name AS "LastName",
e.email AS "EmailAddress",
e.phone_number AS "PHONE_NUMBER",
e.hire_date AS "StartDate",
j.job_title AS "JobTitle",
e.salary AS "Salary",
m.first_name || ' ' ||
m.last_name AS "Manager"),
XMLElement("Commission", e.commission_pct)))
FROM hr.employees e, hr.employees m, hr.jobs j
WHERE e.department_id = d.department_id
AND j.job_id = e.job_id
AND m.employee_id = e.manager_id))).extract('/*')
AS XML
FROM hr.departments d, hr.countries c, hr.locations l
WHERE d.location_id = l.location_id
AND l.country_id = c.country_id;
View created.

The XMLType view lets relational data be persisted as XML content. Rows in XMLType
views can be persisted as documents in Oracle XML DB Repository. The contents of an
XMLType view can be queried, as shown in Example 3–43.
Example 3–43 shows a simple query against an XMLType view. The XPath expression
passed to SQL/XML function XMLExists restricts the result set to the node that
contains the Executive department information. The result is shown pretty-printed
here for clarity.
Example 3–43

Querying XMLType Views

SELECT OBJECT_VALUE FROM department_xml
WHERE XMLExists('$p/Department[Name="Executive"]' PASSING OBJECT_VALUE AS "p");
OBJECT_VALUE
-----------------------------------------------
Executive

2004 Charade Rd
Seattle
Washington
98199
United States of America

Using Oracle XML DB 3-61

Generating XML Data from Relational Data




Neena
Kochhar
NKOCHHAR
515.123.4568
2005-09-21
Administration Vice President
17000
Steven King



Lex
De Haan
LDEHAAN
515.123.4569
2001-01-13
Administration Vice President
17000
Steven King




1 row selected.

As can be seen from the following execution plan output, Oracle XML DB is able to
correctly rewrite the XPath-expression argument in the XMLExists expression into a
SELECT statement on the underlying relational tables.
SELECT OBJECT_VALUE FROM department_xml
WHERE XMLExists('$p/Department[Name="Executive"]' PASSING OBJECT_VALUE AS "p");
PLAN_TABLE_OUTPUT
------------------------------------------------------------------------------------------------------Plan hash value: 2414180351
---------------------------------------------------------------------------------------------------| Id | Operation
| Name
| Rows | Bytes | Cost (%CPU)| Time
|
---------------------------------------------------------------------------------------------------|
0 | SELECT STATEMENT
|
|
1 |
80 |
3
(0)| 00:00:01 |
|
1 | SORT AGGREGATE
|
|
1 |
115 |
|
|
|* 2 |
HASH JOIN
|
|
10 | 1150 |
7 (15)| 00:00:01 |
|* 3 |
HASH JOIN
|
|
10 |
960 |
5 (20)| 00:00:01 |
|
4 |
TABLE ACCESS BY INDEX ROWID| EMPLOYEES
|
10 |
690 |
2
(0)| 00:00:01 |
|* 5 |
INDEX RANGE SCAN
| EMP_DEPARTMENT_IX |
10 |
|
1
(0)| 00:00:01 |
|
6 |
TABLE ACCESS FULL
| JOBS
|
19 |
513 |
2
(0)| 00:00:01 |
|
7 |
TABLE ACCESS FULL
| EMPLOYEES
|
107 | 2033 |
2
(0)| 00:00:01 |
|
8 | NESTED LOOPS
|
|
1 |
80 |
3
(0)| 00:00:01 |
|
9 |
NESTED LOOPS
|
|
1 |
68 |
3
(0)| 00:00:01 |
|* 10 |
TABLE ACCESS FULL
| DEPARTMENTS
|
1 |
19 |
2
(0)| 00:00:01 |
| 11 |
TABLE ACCESS BY INDEX ROWID | LOCATIONS
|
1 |
49 |
1
(0)| 00:00:01 |
|* 12 |
INDEX UNIQUE SCAN
| LOC_ID_PK
|
1 |
|
0
(0)| 00:00:01 |
|* 13 |
INDEX UNIQUE SCAN
| COUNTRY_C_ID_PK
|
1 |
12 |
0
(0)| 00:00:01 |
---------------------------------------------------------------------------------------------------Predicate Information (identified by operation id):
--------------------------------------------------2 - access("M"."EMPLOYEE_ID"="E"."MANAGER_ID")

3-62 Oracle XML DB Developer's Guide

Generating XML Data from Relational Data

3
5
10
12
13

-

access("J"."JOB_ID"="E"."JOB_ID")
access("E"."DEPARTMENT_ID"=:B1)
filter("D"."DEPARTMENT_NAME"='Executive')
access("D"."LOCATION_ID"="L"."LOCATION_ID")
access("L"."COUNTRY_ID"="C"."COUNTRY_ID")

30 rows selected.

Note: XPath rewrite on XML expressions that operate on XMLType
views is only supported when nodes referenced in the XPath
expression are not descendants of an element created using SQL
function XMLAgg.

Generating XML Data from Relational Data using DBURITYPE
You can also generate XML from relational data using SQL function DBURIType.
Function DBURIType exposes one or more rows in a given table or view as a single
XML document. The name of the root element is derived from the name of the table or
view. The root element contains a set of ROW elements. There is one ROW element for
each row in the table or view. The children of each ROW element are derived from the
columns in the table or view. Each child element contains a text node with the value of
the column for the given row.
Example 3–44 shows how to use SQL function DBURIType to access the contents of
table departments in database schema HR. It uses method getXML() to return the
resulting document as an XMLType instance.
Example 3–44
getXML()

Generating XML Data from a Relational Table using DBURIType and

SELECT DBURIType('/HR/DEPARTMENTS').getXML() FROM DUAL;
DBURITYPE('/HR/DEPARTMENTS').GETXML()
-----------------------------------------------------


10
Administration
200
1700

...

20
Marketing
201
1800



Example 3–45 shows how to use an XPath predicate to restrict the rows that are
included in an XML document generated using DBURIType. The XPath expression in
the example restricts the XML document to DEPARTMENT_ID columns with value 10.
Example 3–45

Restricting Rows using an XPath Predicate

SELECT DBURIType('/HR/DEPARTMENTS/ROW[DEPARTMENT_ID="10"]').getXML()
FROM DUAL;

Using Oracle XML DB 3-63

XSL Transformation and Oracle XML DB

DBURITYPE('/HR/DEPARTMENTS/ROW[DEPARTMENT_ID="10"]').GETXML()
-----------------------------------------------------------------

10
Administration
200
1700

1 row selected.

SQL function DBURIType provides a simple way to expose some or all rows in a
relational table as one or more XML documents. The URL passed to function
DBURIType can be extended to return a single column from the view or table, but in
that case the URL must also include predicates that identify a single row in the target
table or view.
Example 3–46 illustrates this. The predicate [DEPARTMENT_ID="10"] causes the
query to return the value of column department_name for the departments row
where column department_id has the value 10.
Example 3–46

Restricting Rows and Columns using an XPath Predicate

SELECT DBURIType(
'/HR/DEPARTMENTS/ROW[DEPARTMENT_ID="10"]/DEPARTMENT_NAME').getXML()
FROM DUAL;
DBURITYPE('/HR/DEPARTMENTS/ROW[DEPARTMENT_ID="10"]/DEPARTMENT_NAME').GETXML()
----------------------------------------------------------------------------
Administration
1 row selected.

SQL function DBURIType is less flexible than the SQL/XML functions:
■

It provides no way to control the shape of the generated document.

■

The data can come only from a single table or view.

■

■

The generated document consists of one or more ROW elements. Each ROW element
contains a child for each column in the target table.
The names of the child elements are derived from the column names.

To control the names of the XML elements, to include columns from more than one
table, or to control which columns from a table appear in the generated document,
create a relational view that exposes the desired set of columns as a single row, and
then use function DBURIType to generate an XML document from the contents of that
view.

XSL Transformation and Oracle XML DB
The W3C XSLT Recommendation defines an XML language for specifying how to
transform XML documents from one form to another. Transformation can include
mapping from one XML schema to another or mapping from XML to some other
format such as HTML or WML.

3-64 Oracle XML DB Developer's Guide

XSL Transformation and Oracle XML DB

See Also: http://www.w3.org/XML/Schema for information
about the XSLT standard

XSL transformation is typically expensive in terms of the amount of memory and
processing required. Both the source document and the style sheet must be parsed and
loaded into memory structures that allow random access to different parts of the
documents. Most XSL processors use DOM to provide the dynamic memory
representation of both documents. The XSL processor then applies the style sheet to
the source document, generating a third document.
Oracle XML DB includes an XSLT processor that lets XSL transformations be
performed inside the database. In this way, Oracle XML DB can provide XML-specific
memory optimizations that significantly reduce the memory required to perform the
transformation. It can also eliminate overhead associated with parsing the documents.
These optimizations are only available when the source for the transformation is a
schema-based XML document, however.
Oracle XML provides three ways to invoke the XSL processor:
■

SQL function XMLtransform

■

XMLType method transform()

■

PL/SQL package DBMS_XSLPROCESSOR

Each of these XML transformation methods takes as input a source XML document
and an XSL style sheet in the form of XMLType instances. For SQL function
XMLtransform and XMLType method transform(), the result of the transformation
can be an XML document or a non-XML document, such as HTML. However, for
PL/SQL package DBMS_XSLPROCESSOR, the result of the transformation is expected
to be a valid XML document. Any HTML generated by a transformation using
package DBMS_XSLPROCESSOR is XHTML, which is both valid XML and valid HTML.
Example 3–47 shows part of an XSLT style sheet, PurchaseOrder.xsl. The complete
style sheet is given in "XSL Style Sheet Example, PurchaseOrder.xsl" on page A-38.
Example 3–47

XSLT Style Sheet Example: PurchaseOrder.xsl













PurchaseOrder 











Using Oracle XML DB 3-65

XSL Transformation and Oracle XML DB
























:


:



'));
SELECT XMLSerialize(DOCUMENT XMLtransform(x.xmlcol, y.stylesheet)
AS varchar2(1000))
AS result FROM po_tab x, stylesheet_tab y WHERE y.id = 1;

This produces the following output (pretty-printed here for readability):
RESULT
--------------------------------------------------------

Example 11–3 illustrates the use of a stored style sheet to transform XMLType
instances. Unlike Example 11–2, Example 11–3 uses a scalar subquery to retrieve the
stored style sheet.

Transforming and Validating XMLType Data

11-5

XMLTRANSFORM and XMLType.transform(): Examples

Example 11–3

Retrieving a Style Sheet using XMLTRANSFORM and a Subquery

SELECT XMLSerialize(DOCUMENT
XMLtransform(
x.xmlcol,
(SELECT stylesheet FROM stylesheet_tab WHERE id = 1))
AS VARCHAR2(1000))
AS result FROM po_tab x;

Example 11–4 uses XMLType method transform() to transform an XMLType
instance using a transient style sheet.
Example 11–4

Using Method TRANSFORM() with a Transient Style Sheet

SELECT XMLSerialize(
DOCUMENT
x.xmlcol.transform(
XMLType('







:



:



'))
AS varchar2(1000))
FROM po_tab x;

11-6 Oracle XML DB Developer's Guide

Validating XMLType Instances

Validating XMLType Instances
Often, besides knowing whether a particular XML document is well-formed, you need
to know whether it conforms to a given XML schema, that is, whether it is valid with
respect to that XML schema.
XML schema-based data that is stored as binary XML it is automatically validated
fully whenever it is inserted or updated. This validation does not require building a
DOM. It is done using streaming, which is efficient and minimizes memory use.
For XMLType data that is stored object-relationally, full validation requires building a
DOM, which can be costly in terms of memory management. For this reason, Oracle
XML DB does not automatically perform full validation when you insert or update
data that is stored object-relationally.
However, in the process of decomposing XML data to store it object-relationally,
Oracle XML DB does automatically perform partial validation, to ensure that the
structure of the XML document conforms to the SQL data type definitions that were
derived from the XML schema.
If you require full validation for XMLType data stored object-relationally, then consider
validating on the client before inserting the data into the database or updating it.
You can use the following to perform full validation and manipulate the recorded
validation status of XML documents:
■

■

■

■

Oracle SQL function XMLIsValid and XMLType method IsSchemaValid() –
Run the validation process unconditionally. Do not record any validation status.
Return:
–

1 if the document is determined to be valid.

–

0 if the document is determined to be invalid or the validity of the document
cannot be determined.

XMLType method SchemaValidate() – Runs the validation process if the
validation status is 0, which it is by default. Sets the validation status to 1 if the
document is determined to be valid. (Otherwise, the status remains 0.)
XMLType method isSchemaValidated() returns the recorded validation status
of an XMLType instance.
XMLType method setSchemaValidated() sets (records) the validation status of
an XMLType instance.

Note that the validation status indicates knowledge of validity, as follows:
■
■

1 means that the document is known to be valid.
0 means that validity of the document is unknown. The document might have been
shown to be invalid during a validation check, but that invalidity is not recorded.
A recorded validation status of 0 indicates only a lack of knowledge about the
document's validity.

Transforming and Validating XMLType Data

11-7

Validating XML Data Stored as XMLType: Examples

See Also:
■
■

■

"Comparing Partial to Full XML Schema Validation" on page 3-32
Oracle Database SQL Language Reference for information about
Oracle SQL function XMLIsValid
Oracle Database PL/SQL Packages and Types Reference for
information about XMLType methods IsSchemaValid(),
IsSchemaValidated(), SchemaValidate(), and
setSchemaValidated()

Validating XML Data Stored as XMLType: Examples
The examples in this section illustrate how to use Oracle SQL function XMLIsValid
and XMLType methods isSchemaValid() and schemaValidate() to validate
XML data being stored as XMLType in Oracle XML DB.
Example 11–5 and Example 11–6 show how to validate an XML instance against an
XML schema using PL/SQL method isSchemaValid().
Example 11–5

Validating XML using Method ISSCHEMAVALID() in SQL

SELECT x.xmlcol.isSchemaValid('http://www.example.com/schemas/ipo.xsd',
'purchaseOrder')
FROM po_tab x;
Example 11–6

Validating XML using Method ISSCHEMAVALID() in PL/SQL

DECLARE
xml_instance XMLType;
BEGIN
SELECT x.xmlcol INTO xml_instance FROM po_tab x WHERE id = 1;
IF xml_instance.isSchemaValid('http://www.example.com/schemas/ipo.xsd') = 0
THEN raise_application_error(-20500, 'Invalid Instance');
ELSE DBMS_OUTPUT.put_line('Instance is valid');
END IF;
END;
/
Instance is valid
PL/SQL procedure successfully completed.

XMLType method schemaValidate() can be used within INSERT and UPDATE
triggers to ensure that all instances stored in the table are validated against the XML
schema. Example 11–7 illustrates this.
Example 11–7

Validating XML using Method SCHEMAVALIDATE() within Triggers

DROP TABLE po_tab;
CREATE TABLE po_tab OF XMLType
XMLSCHEMA "http://www.example.com/schemas/ipo.xsd" ELEMENT "purchaseOrder";
CREATE TRIGGER emp_trig BEFORE INSERT OR UPDATE ON po_tab FOR EACH ROW
DECLARE
newxml XMLType;
BEGIn
newxml := :new.OBJECT_VALUE;
XMLTYPE.schemavalidate(newxml);
END;
11-8 Oracle XML DB Developer's Guide

Validating XML Data Stored as XMLType: Examples

/

Example 11–8 uses Oracle SQL function XMLIsValid to do the following:
■

Verify that the XMLType instance conforms to the specified XML schema

■

Ensure that the incoming XML documents are valid by using CHECK constraints

Example 11–8

Checking XML Validity using XMLISVALID within CHECK Constraints

DROP TABLE po_tab;
CREATE TABLE po_tab OF XMLType
(CHECK(XMLIsValid(OBJECT_VALUE) = 1))
XMLSCHEMA "http://www.example.com/schemas/ipo.xsd" ELEMENT "purchaseOrder";

Note: The validation functions and procedures described in
section "Validating XMLType Instances" facilitate validation
checking. Of these, schemaValidate is the only one that raises
errors that indicate why validation has failed.

Transforming and Validating XMLType Data

11-9

Validating XML Data Stored as XMLType: Examples

11-10 Oracle XML DB Developer's Guide

12
Full-Text Search Over XML Data
This chapter describes full-text search over XML using Oracle. It explains how to use
Oracle SQL function contains and Oracle XPath function ora:contains. These are
the two functions used by Oracle Database to do full-text search over XML data.
See Also: Oracle Text Reference and Oracle Text Application
Developer's Guide for more information about Oracle Text

This chapter contains these topics:
■

Overview of Full-Text Search for XML

■

About the Full-Text Search Examples

■

Overview of CONTAINS and ora:contains

■

CONTAINS SQL Function

■

ora:contains XQuery Function

■

Text Path BNF Specification

■

Support for Full-Text XML Examples

Overview of Full-Text Search for XML
Oracle supports full-text search on documents that are managed by the Oracle
Database.
If your documents are XML, then you can use the XML structure of the document to
restrict the full-text search. For example, you may want to find all purchase orders that
contain the word "electric" using full-text search. If the purchase orders are in XML
form, then you can restrict the search by finding all purchase orders that contain the
word "electric" in a comment, or by finding all purchase orders that contain the word
"electric" in a comment under line items.
If your XML documents are of type XMLType, then you can project the results of your
query using the XML structure of the document. For example, after finding all
purchase orders that contain the word "electric" in a comment, you may want to return
just the comments, or just the comments that contain the word "electric".

Comparison of Full-Text Search and Other Search Types
Full-text search differs from structured search or substring search in the following
ways:

Full-Text Search Over XML Data 12-1

About the Full-Text Search Examples

■

■

■

A full-text search looks for whole words rather than substrings. A substring search
for comments that contain the string "law" can return a comment that contains "my
lawn is going wild". A full-text search for the word "law" cannot.
A full-text search supports some language-based and word-based searches that
substring searches do not. You can use a language-based search, for example, to
find all the comments that contain a word with the same linguistic stem as
"mouse", and Oracle Text finds "mouse" and "mice". You can use a word-based
search, for example, to find all the comments that contain the word "lawn" within
5 words of "wild".
A full-text search generally involves some notion of relevance. When you do a
full-text search for all the comments that contain the word "lawn", for example,
some results are more relevant than others. Relevance is often related to the
number of times the search word (or similar words) occur in the document.

Searching XML Data
XML search is different from unstructured document search. In unstructured
document search you generally search across a set of documents to return the
documents that satisfy your text predicate. In XML search you often want to use the
structure of the XML document to restrict the search. And you often want to return
just the part of the document that satisfies the search.

Searching Documents using Full-Text Search and XML Structure
There are two ways to do a search that includes full-text search and XML structure:
■

Include the structure inside the full-text predicate, using Oracle SQL function
contains:
WHERE contains(doc, 'electric INPATH (/purchaseOrder/items/item/comment)') > 0

Function contains is an extension to SQL, and can be used in any query. It
requires a CONTEXT full-text index.
■

Include the full-text predicate inside the structure, using XPath function
ora:contains:
'/purchaseOrder/items/item/comment[ora:contains(text(), "electric")>0]'

XPath function ora:contains is an extension to XPath, and can be used in a call
to SQL/XML function XMLQuery, XMLTable, or XMLExists.

About the Full-Text Search Examples
This section describes details about the examples included in this chapter.

Roles and Privileges
To run the examples, you need database roles CTXAPP, CONNECT, and RESOURCE. You
must also have EXECUTE privilege on the CTXSYS package CTX_DDL.

Schema and Data for Full-Text Search Examples
Examples in this chapter are based on "The Purchase Order Schema", W3C XML
Schema Part 0: Primer.

12-2 Oracle XML DB Developer's Guide

Overview of CONTAINS and ora:contains

See Also:

http://www.w3.org/TR/xmlschema-0/#POSchema
The data in the examples is from the document "Purchase-Order XML Document,
po001.xml" on page 12-26.
The tables used in the examples of this chapter are defined in section "CREATE TABLE
Statements""CREATE TABLE Statements". Some of the performance examples are,
however, based on a larger table (purchase_orders_xmltype_big), which is
included in the downloadable version only. See
http://www.w3.org/TR/xmlschema-0/#po.xml.
Some of the examples here use data type VARCHAR2. Others use type XMLType. All
examples that use VARCHAR2 also work with XMLType.

Overview of CONTAINS and ora:contains
This section contains these topics:
■

Overview of SQL Function CONTAINS

■

Overview of XPath Function ora:contains

■

Comparison of CONTAINS and ora:contains

Overview of SQL Function CONTAINS
Oracle SQL function contains returns a positive number for rows where
[schema.]column matches text_query. Otherwise, it returns zero. It requires an
index of type CONTEXT. If there is no CONTEXT index on the column being searched,
then contains raises an error.

CONTAINS Syntax
contains([schema.]column, text_query VARCHAR2 [,label NUMBER])
RETURN NUMBER

Example 12–1 shows a typical query that uses Oracle SQL function contains. It
returns the id for each row in table purchase_orders where the doc column
contains the word "lawn" and id is less than 25.
Example 12–1

Simple Query using Oracle SQL Function CONTAINS

SELECT id FROM purchase_orders WHERE contains(doc, 'lawn') > 0 AND id < 25;

Suppose doc is a column that contains a set of XML documents. You can do full-text
search over doc, using its XML structure to restrict the query. The query in
Example 12–2 returns id values for table purchaseorders where column doc
contains the word "lawn" in the text() node of XML element comment.
Example 12–2

Restricting a Query using CONTAINS and WITHIN

SELECT id FROM purchase_orders WHERE contains(doc, 'lawn WITHIN comment') > 0;

More complex XML structure restrictions can be applied using the INPATH operator
and an XPath expression. The query in Example 12–3 finds purchase orders that
contain the word "electric" in the text() node of a comment element that is targeted by
XPath expression/purchaseOrder/items/item/comment.

Full-Text Search Over XML Data 12-3

Overview of CONTAINS and ora:contains

Example 12–3

Restricting a Query using CONTAINS and INPATH

SELECT id FROM purchase_orders
WHERE contains(doc, 'electric INPATH (/purchaseOrder/items/item/comment)') > 0;

Overview of XPath Function ora:contains
XPath function ora:contains can be used in an XPath expression inside an XQuery
expression or in a call to SQL/XML function XMLQuery, XMLTable, or XMLExists. It
is used to restrict a structural search with a full-text predicate. It extends XPath
through a standard mechanism: it is a user-defined function in the Oracle XML DB
namespace, ora. It requires no index, but you can use an index with it to improve
performance.

ora:contains Syntax
ora:contains(input_text NODE*, text_query STRING
[,policy_name STRING]
[,policy_owner STRING])

Function ora:contains returns a positive integer when the input_text matches
text_query (the higher the number, the more relevant the match), and zero
otherwise. When used in an XQuery expression, the XQuery return type is
xs:integer(). When used in an XPath expression outside of an XQuery expression,
the XPath return type is number.
Argument input_text must evaluate to a single text node or an attribute. The syntax
and semantics of text_query in ora:contains are the same as text_query in
contains, with the following restrictions:
■

■

Argument text_query cannot include any structure operators (WITHIN,
INPATH, or HASPATH).
If the weight score-weighting operator is used, the weights are ignored.

Example 12–4 shows a call to ora:contains in the XPath parameter to XMLExists.
Notice the namespace declaration that declares prefix ora as representing the Oracle
XML DB namespace.
Example 12–4

ora:contains with an Arbitrarily Complex Text Query

SELECT id
FROM purchase_orders_xmltype
WHERE
XMLExists(
'declare namespace ora = "http://xmlns.oracle.com/xdb"; (: :)
$d/purchaseOrder/comment
[ora:contains(text(), "($lawns AND wild) OR flamingo") > 0]'
PASSING doc AS "d");

"ora:contains XQuery Function" on page 12-17 for more
on the ora:contains XPath function

See Also:

Comparison of CONTAINS and ora:contains
Both Oracle SQL function contains and Oracle XPath function ora:contains let
you combine searching on XML structure with full-text searching. These are the main
differences between them:
Oracle SQL function contains:
■

Needs a CONTEXT index to run. If there is no index, then an error is raised.

12-4 Oracle XML DB Developer's Guide

CONTAINS SQL Function

■

Does an indexed search and is generally very fast.

■

Returns a score (through Oracle SQL function score).

■

Restricts a search based on documents (rows in a table) rather than nodes.

■

Cannot be used for XML structure-based projection (extracting parts of an XML
document).

Oracle XPath function ora:contains:
■

Does not need an index to run, but you can use an index to improve performance.

■

Might do an unindexed search, so it might be resource-intensive.

■

Separates application logic from storing and indexing considerations.

■

Does not return a score.

■

Can be used for XML structure-based projection (extracting parts of an XML
document).

Use Oracle SQL function contains when you want a fast, index-based, full-text
search over XML documents, possibly with simple XML structure constraints. Use
Oracle XPath function ora:contains when you need the flexibility of full-text search
combined with XPath navigation (possibly without an index) or when you need to do
projection, and you do not need a score.

CONTAINS SQL Function
This section contains these topics:
■

Full-Text Search using SQL Function CONTAINS

■

SCORE SQL Function

■

Restricting the Scope of a CONTAINS Search

■

Projecting the CONTAINS Result

■

Indexing with a CONTEXT Index

Full-Text Search using SQL Function CONTAINS
The second argument to Oracle SQL function contains, text_query, is a string that
specifies the full-text search. text_query has its own language, based on the
SQL/MM Full-Text standard.
See Also:
■

■

ISO/IEC 13249-2:2000, Information technology - Database
languages - SQL Multimedia and Application Packages - Part 2:
Full-Text, International Organization For Standardization, 2000
Oracle Text Reference for more information about the operators
in the text_query language

The examples in the rest of this section show some of the power of full-text search.
They use only a few of the available operators. The example queries search over a
VARCHAR2 column (PURCHASE_ORDERS.doc) with a text index (index type
CTXSYS.CONTEXT).

Full-Text Search Over XML Data 12-5

CONTAINS SQL Function

Full-Text Boolean Operators AND, OR, and NOT
The text_query language supports arbitrary combinations of AND, OR, and NOT.
Precedence can be controlled using parentheses. The Boolean operators can be written
in any of the following ways:
■

AND, OR, NOT

■

and, or, not

■

&, |, ~

Note that NOT is a binary, not a unary operator here. The expression alpha
NOT(beta) is equivalent to alpha AND unary-not(beta), where unary-not stands
for unary negation.
See Also: Oracle Text Reference for complete information about the
operators you can use in contains and ora:contains
Example 12–5

CONTAINS Query with a Simple Boolean Operator

SELECT id FROM purchase_orders WHERE contains(doc, 'lawn AND wild') > 0;
Example 12–6

CONTAINS Query with Complex Boolean

SELECT id FROM purchase_orders
WHERE contains(doc, '((lawn OR garden) AND (wild OR flooded)) NOT(flamingo)')
> 0;

Full-Text Stemming: $
The text_query language supports stemmed search. Example 12–7 returns all
documents that contain some word with the same linguistic stem as "lawns", so it finds
"lawn" or "lawns". The stem operator is written as a dollar sign ($).
Example 12–7

CONTAINS Query with Stemming

SELECT id FROM purchase_orders WHERE contains(doc, '$(lawns)') > 0;

Combining Boolean and Stemming Operators
You can combine operators in the text_query language, as shown in Example 12–8.
Example 12–8

CONTAINS Query with Complex Query Expression

SELECT id FROM purchase_orders
WHERE contains(doc, '($lawns AND wild) OR flamingo') > 0;

See Also: Oracle Text Reference for a full list of text_query
operators

SCORE SQL Function
Oracle SQL function score is related to Oracle SQL function contains. Function
score can be used anywhere in a query. It is a measure of relevance, and it is
especially useful when doing full-text searches across large document sets. Function
score is typically returned as part of the query result, used in the ORDER BY clause,
or both.

SCORE Syntax
score(label NUMBER) RETURN NUMBER

12-6 Oracle XML DB Developer's Guide

CONTAINS SQL Function

In Example 12–9, score(10) returns the score for each row in the result set. Oracle
SQL function score returns the relevance of a row in the result set with respect to a
particular call to function contains. A call to score is linked to a call to contains
by a LABEL (in this case the number 10).
Example 12–9

Simple CONTAINS Query with SCORE

SELECT score(10), id FROM purchase_orders
WHERE contains(doc, 'lawn', 10) > 0 AND score(10) > 2
ORDER BY score(10) DESC;

Function score always returns 0 if, for the corresponding contains expression,
argument text_query does not match input_text, according to the matching rules
dictated by the text index. If the contains text_query matches the input_text,
then score returns a number greater than 0 and less than or equal to 100. This
number indicates the relevance of the text_query to the input_text. A higher
number means a better match.
If the contains text_query consists of only the HASPATH operator and a Text Path,
the score is either 0 or 100, because HASPATH tests for an exact match.
See Also: Oracle Text Reference for details on how the score is
calculated

Restricting the Scope of a CONTAINS Search
Oracle SQL function contains does a full-text search across the whole document, by
default. In the example heres, a search for "lawn" with no structure restriction finds all
purchase orders with the word "lawn" anywhere in them.
There are three ways to restrict contains queries using XML structure:
■

WITHIN

■

INPATH

■

HASPATH
For the purposes of this discussion, consider section to be
the same as an XML node.

Note:

WITHIN Structure Operator
The WITHIN operator restricts a query to some section within an XML document. A
search for purchase orders that contain the word "lawn" somewhere inside a comment
section might use WITHIN. Section names are case-sensitive.
Example 12–10 WITHIN
SELECT id FROM purchase_orders WHERE contains(DOC, 'lawn WITHIN comment') > 0;

Nested WITHIN You can restrict the query further by nesting WITHIN. Example 12–11
finds all documents that contain the word "lawn" within a section "comment", where
that occurrence of "lawn" is also within a section "item".
Example 12–11 Nested WITHIN
SELECT id FROM purchase_orders
WHERE contains(doc, '(lawn WITHIN comment) WITHIN item') > 0;

Full-Text Search Over XML Data 12-7

CONTAINS SQL Function

Example 12–11 returns no rows. Our sample purchase order does contain the word
"lawn" within a comment. But the only comment within an item is "Confirm this
is electric". So the nested WITHIN query returns no rows.
WITHIN Attributes You can also search within attributes. Example 12–12 finds all
purchase orders that contain the word 10 in the orderDate attribute of a
purchaseOrder element.
Example 12–12 WITHIN an Attribute
SELECT id FROM purchase_orders
WHERE contains(doc, '10 WITHIN purchaseOrder@orderDate') > 0;

By default, the minus sign ("-") is treated as a word separator: "1999-10-20" is
treated as the three words "1999", "10" and "20". So this query returns one row.
Text in an attribute is not a part of the main searchable document. A search for 10
without qualifying the text_query with WITHIN purchaseOrder@orderDate
returns no rows.
You cannot search attributes in a nested WITHIN.
WITHIN and AND Suppose you want to find purchase orders that contain two words
within a comment section: "lawn" and "electric". There can be more than one comment
section in a purchaseOrder. So there are two ways to write this query, with two
distinct results.
If you want to find purchase orders that contain both words, where each word occurs
in some comment section, you would write a query like Example 12–13.
Example 12–13 WITHIN and AND: Two Words in Some Comment Section
SELECT id FROM purchase_orders
WHERE contains(doc, '(lawn WITHIN comment) AND (electric WITHIN comment)') > 0;

If you run this query against the purchaseOrder data, then it returns 1 row. Note
that the parentheses are not needed in this example, but they make the query more
readable.
If you want to find purchase orders that contain both words, where both words occur
in the same comment, you would write a query like Example 12–14.
Example 12–14 WITHIN and AND: Two Words in the Same Comment
SELECT id FROM purchase_orders
WHERE contains(doc, '(lawn AND electric) WITHIN comment') > 0;

The query in Example 12–14 returns no rows. The query in Example 12–15, which
omits the parentheses around lawn AND electric, returns one row.
Example 12–15 WITHIN and AND: No Parentheses
SELECT id FROM purchase_orders
WHERE contains(doc, 'lawn AND electric WITHIN comment') > 0;

Operator WITHIN has a higher precedence than AND, so Example 12–15 is parsed as
Example 12–16.

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Example 12–16 WITHIN and AND: Parentheses Illustrating Operator Precedence
SELECT id FROM purchase_orders
WHERE contains(doc, 'lawn AND (electric WITHIN comment)') > 0;

Definition of Section The preceding examples have used the WITHIN operator to search
within a section. A section can be a:
■

path or zone section
This is a concatenation, in document order, of all text nodes that are descendants
of a node, with whitespace separating the text nodes. To convert from a node to a
zone section, you must serialize the node and replace all tags with whitespace.
path sections have the same scope and behavior as zone sections, except that path
sections support queries with INPATH and HASPATH structure operators.

■

field section
This is the same as a zone section, except that repeating nodes in a document are
concatenated into a single section, with whitespace as a separator.

■

attribute section

■

special section (sentence or paragraph)
See Also: Oracle Text Reference for more information about special
sections

INPATH Structure Operator
Operator WITHIN provides an easy and intuitive way to express simple structure
restrictions in the text_query. For queries that use abundant XML structure, you can
use operator INPATH plus a text path instead of nested WITHIN operators.
Operator INPATH takes a text_query on the left and a Text Path, enclosed in
parentheses, on the right. Example 12–17 finds purchaseOrders that contain the
word "electric" in the path /purchaseOrder/items/item/comment.
Example 12–17 Structure Inside Full-Text Predicate: INPATH
SELECT id FROM purchase_orders
WHERE contains(doc, 'electric INPATH (/purchaseOrder/items/item/comment)') > 0;

The scope of the search in Example 12–17 is the section indicated by the Text Path. The
query in Example 12–18 uses a broader path than the query in Example 12–17, but it
too returns one row.
Example 12–18 Structure Inside Full-Text Predicate: INPATH
SELECT id FROM purchase_orders
WHERE contains(doc, 'electric INPATH (/purchaseOrder/items)') > 0;

Text Path The syntax and semantics of Text Path are based on the w3c XPath 1.0
recommendation. Simple path expressions are supported (abbreviated syntax only),
but functions are not. The following examples are meant to give the general flavor.
See Also:
■

■

http://www.w3.org/TR/xpath for information about the
W3C XPath 1.0 recommendation
"Text Path BNF Specification" on page 12-25 for the Text Path
grammar
Full-Text Search Over XML Data 12-9

CONTAINS SQL Function

Example 12–19 finds all purchase orders that contain the word "electric" in a
comment element that is the child of an item element with a partNum attribute
whose value is "872-AA", which in turn is the child of an items element that is any
number of levels under the root node.
Example 12–19 INPATH with Complex Path Expression (1)
SELECT id FROM purchase_orders
WHERE contains(doc, 'electric INPATH (//items/item[@partNum="872-AA"]/comment)')
> 0;

Example 12–20 finds all purchase orders that contain the word "lawnmower" in a
third-level item element (or any of its descendants) that has a comment element
descendant at any level. This query returns one row. The scope of the query is not a
comment element, but the set of items elements that each have a comment element as
a descendant.
Example 12–20 INPATH with Complex Path Expression (2)
SELECT id FROM purchase_orders
WHERE contains(doc, 'lawnmower INPATH (/*/*/item[.//comment])') > 0;

Text Path Compared to XPath The Text Path language differs from the XPath language in
the following ways:
■

Not all XPath operators are included in the Text Path language.

■

XPath built-in functions are not included in the Text Path language.

■

Text Path language operators are case-insensitive.

■

If you use = inside a filter (brackets), then matching follows text-matching rules.
Rules for case-sensitivity, normalization, stopwords and whitespace depend on the
text index definition. To emphasize this difference, this kind of equality is referred
to here as text-equals.

■

Namespace support is not included in the Text Path language.
The name of an element, including a namespace prefix if it exists, is treated as a
string. So two different namespace prefixes that map to the same namespace URI
are not treated as equivalent in the Text Path language.

■

In a Text Path, the context is always the root node of the document.
So in the purchase-order data, purchaseOrder/items/item,
/purchaseOrder/items/item, and ./purchaseOrder/items/item are all
equivalent.

■

■

If you want to search within an attribute value, then the direct parent of the
attribute must be specified (wildcards cannot be used).
A Text Path may not end in a wildcard (*).
See Also: "Text Path BNF Specification" on page 12-25 for the Text
Path grammar

Nested INPATH You can nest INPATH expressions. The context for the Text Path is
always the root node. It is not changed by a nested INPATH.
Example 12–21 finds purchase orders that contain the word "electric" inside a
comment element at any level, where the occurrence of that word is also in an items
element that is a child of the top-level purchaseOrder element.
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Example 12–21 Nested INPATH
SELECT id FROM purchase_orders
WHERE contains(doc,
'(electric INPATH (//comment)) INPATH (/purchaseOrder/items)')
> 0;

This nested INPATH query could be written more concisely as shown in
Example 12–22.
Example 12–22 Nested INPATH Rewritten
SELECT id FROM purchase_orders
WHERE contains(doc, 'electric INPATH (/purchaseOrder/items//comment)') > 0;

HASPATH Structure Operator
Operator HASPATH takes only one operand: a Text Path, enclosed in parentheses, on
the right. Use HASPATH when you want to find documents that contain a particular
section in a particular path, possibly with predicate =. This is a path search rather than
a full-text search. You can check for the existence of a section, or you can match the
contents of a section, but you cannot do word searches. If your data is of type
XMLType, then consider using SQL/XML function XMLExists instead of structure
operator HASPATH.
Example 12–23 finds purchaseOrders that have some item that has a USPrice.
Example 12–23 Simple HASPATH
SELECT id FROM purchase_orders
WHERE contains(DOC, 'HASPATH (/purchaseOrder//item/USPrice)') > 0;

Example 12–24 finds purchaseOrders that have some item that has a USPrice that
text-equals "148.95".
See Also: "Text Path Compared to XPath" on page 12-10 for an
explanation of text-equals
Example 12–24 HASPATH Equality
SELECT id FROM purchase_orders
WHERE contains(doc, 'HASPATH (/purchaseOrder//item/USPrice="148.95")') > 0;

HASPATH can be combined with other contains operators such as INPATH.
Example 12–25 finds purchaseOrders that contain the word electric anywhere in
the document and have some item that has a USPrice that text-equals 148.95 and
contain 10 in the purchaseOrder attribute orderDate.
Example 12–25 HASPATH with Other Operators
SELECT id FROM purchase_orders
WHERE contains(doc,
'electric
AND HASPATH (/purchaseOrder//item/USPrice="148.95")
AND 10 INPATH (/purchaseOrder/@orderDate)')
> 0;

Full-Text Search Over XML Data 12-11

CONTAINS SQL Function

Projecting the CONTAINS Result
The result of a SQL query with a contains expression in the WHERE clause is always
a set of rows (and possibly score information), or a projection over the rows that
match the query.
If you want to return only a part of each XML document that satisfies a contains
expression, then use SQL/XML function XMLQuery. The examples in this section use
the XMLType table purchase_orders_xmltype.
Example 12–26 finds purchaseOrders that contain the word "electric" inside a
comment element that is a descendant of the top-level element purchaseOrder.
Instead of returning the ID of the row for each result, XMLQuery is used to return only
the comment element.
Example 12–26 Scoping the Results of a CONTAINS Query
SELECT XMLQuery('declare namespace ora = "http://xmlns.oracle.com/xdb"; (: :)
$d/purchaseOrder//comment'
PASSING doc AS "d" RETURNING CONTENT) "Item Comment"
FROM purchase_orders_xmltype
WHERE CONTAINS(doc, 'electric INPATH (/purchaseOrder//comment)') > 0;

The result of Example 12–26 is two instances of element comment. Function contains
indicates which rows contain the word "electric" inside a comment element (the
row with ID = 1), and function XMLQuery extracts all of the instances of element
comment in the document at that row. There are two instances of element comment
inside the purchaseOrder element, and the query returns both of them.
This might not be what you want. If you want the query to return only the instances of
element comment that satisfy the contains expression, then you must repeat that
predicate in the XQuery expression passed to XMLQuery. You do that using XPath
function ora:contains. Example 12–27 illustrates this.
Example 12–27 Projecting the Result of a CONTAINS Query using ora:contains
SELECT XMLQuery('declare namespace ora = "http://xmlns.oracle.com/xdb"; (: :)
$d/purchaseOrder/items/item/comment
[ora:contains(text(), "electric") > 0]'
PASSING doc AS "d" RETURNING CONTENT) "Item Comment"
FROM purchase_orders_xmltype
WHERE CONTAINS(doc, 'electric INPATH (/purchaseOrder/items/item/comment)') > 0;

Indexing with a CONTEXT Index
This section contains these topics:
■

Introduction to CONTEXT Indexes

■

Effect of a CONTEXT Index on CONTAINS

■

CONTEXT Index Preferences

■

Introduction to Section Groups

Introduction to CONTEXT Indexes
The general-purpose full-text index type is CONTEXT, which is owned by database
user CTXSYS. To create a default full-text index, use the regular SQL CREATE INDEX
command, and add the clause INDEXTYPE IS CTXSYS.CONTEXT, as shown in
Example 12–28.

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Example 12–28 Simple CONTEXT Index on Table PURCHASE_ORDERS
CREATE INDEX po_index ON purchase_orders(doc)
INDEXTYPE IS CTXSYS.CONTEXT;

You have many choices available when building a full-text index. These choices are
expressed as indexing preferences. To use an indexing preference, add the
PARAMETERS clause to CREATE INDEX, as shown in Example 12–29.
See Also:

"CONTEXT Index Preferences" on page 12-14

Example 12–29 Simple CONTEXT Index on XMLType Table with Path Section Group
CREATE INDEX po_index ON purchase_orders(doc)
INDEXTYPE IS CTXSYS.CONTEXT
PARAMETERS ('section group CTXSYS.PATH_SECTION_GROUP');

Oracle Text provides other index types, such as CTXCAT and CTXRULE, which are
outside the scope of this chapter.
See Also: Oracle Text Reference for more information about
CONTEXT indexes

CONTEXT Index on XMLType Table You can build a CONTEXT index on any data that
contains text. Example 12–28 creates a CONTEXT index on a VARCHAR2 column. The
syntax to create a CONTEXT index on a column of type CHAR, VARCHAR, VARCHAR2,
BLOB, CLOB, BFILE, XMLType, or URIType is the same. Example 12–30 creates a
CONTEXT index on a column of type XMLType. The section group defaults to PATH_
SECTION_GROUP.
Example 12–30 Simple CONTEXT Index on XMLType Column
CREATE INDEX po_index_xmltype ON purchase_orders_xmltype(doc)
INDEXTYPE IS CTXSYS.CONTEXT;

If you have an XMLType table, then you must use object syntax to create the CONTEXT
index, as shown in Example 12–31.
Example 12–31 Simple CONTEXT Index on XMLType Table
CREATE INDEX po_index_xmltype_table
ON purchase_orders_xmltype_table (OBJECT_VALUE)
INDEXTYPE IS CTXSYS.CONTEXT;

You can query the table as shown in Example 12–32.
Example 12–32 CONTAINS Query on XMLType Table
SELECT XMLCast(XMLQuery(
'declare namespace ora = "http://xmlns.oracle.com/xdb"; (: :)
$p/purchaseOrder/@orderDate'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS DATE) "Order Date"
FROM purchase_orders_xmltype_table po
WHERE contains(po.OBJECT_VALUE, 'electric INPATH (/purchaseOrder//comment)')
> 0;

Maintaining a CONTEXT Index The CONTEXT index, like most full-text indexes, is
asynchronous. When indexed data is changed, the CONTEXT index might not change
until you take some action, such as calling a procedure to synchronize the index.
Full-Text Search Over XML Data 12-13

CONTAINS SQL Function

The CONTEXT index can become fragmented over time. A fragmented index uses more
space and leads to slower queries. There are a number of ways to optimize
(defragment) the CONTEXT index.
See Also: Oracle Text Reference for more information about
CONTEXT index maintenance

Roles and Privileges You do not need any special privileges to create a CONTEXT index.
You need the CTXAPP role to create and delete preferences and to use the Oracle Text
PL/SQL packages. You must also have EXECUTE privilege on the CTXSYS package
CTX_DDL.

Effect of a CONTEXT Index on CONTAINS
To use Oracle SQL function contains, you must create an index of type CONTEXT. If
you call contains, and the column given in the first argument does not have an
index of type CONTEXT, then an error is raised.
The syntax and semantics of text_query depend on the choices you make when you
build the CONTEXT index. For example:
■

What counts as a word?

■

Are very common words processed?

■

What is a common word?

■

Is the text search case-sensitive?

■

Can the text search include themes (concepts) in addition to keywords?

CONTEXT Index Preferences
A preference can be considered a collection of indexing choices. Preferences include
section group, datastore, filter, wordlist, stoplist and storage. This section shows how
to set up a lexer preference to make searches case-sensitive.
You can use procedure CTX_DDL.create_preference (or CTX_DDL.create_
stoplist) to create a preference. Override default choices in that preference group by
setting attributes of the new preference, using procedure CTX_DDL.set_attribute.
Then use the preference in a CONTEXT index by including preference type
preference_name in the PARAMETERS string of CREATE INDEX.
Once a preference has been created, you can use it to build any number of indexes.
Making Search Case-Sensitive Full-text searches with contains are case-insensitive by
default. That is, when matching words in text_query against words in the
document, case is not considered. Section names and attribute names, however, are
always case-sensitive.
If you want full-text searches to be case-sensitive, then you need to make that choice
when building the CONTEXT index. Example 12–33 returns 1 row, because "HURRY" in
text_query matches "Hurry" in the purchaseOrder with the default
case-insensitive index.
Example 12–33 CONTAINS: Default Case Matching
SELECT id FROM purchase_orders
WHERE contains(doc, 'HURRY INPATH (/purchaseOrder/comment)') > 0;

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Example 12–34 creates a new lexer preference my_lexer, with the attribute mixed_
case set to TRUE. It also sets printjoin characters to "-" and "!" and ",". You can use
the same preferences for building CONTEXT indexes and for building policies.
See Also:

Oracle Text Reference for a full list of lexer attributes

Example 12–34 Create a Preference for Mixed Case
BEGIN
CTX_DDL.create_preference(PREFERENCE_NAME
OBJECT_NAME

=>
=>

'my_lexer',
'BASIC_LEXER');

CTX_DDL.set_attribute(PREFERENCE_NAME
ATTRIBUTE_NAME
ATTRIBUTE_VALUE

=>
=>
=>

'my_lexer',
'mixed_case',
'TRUE');

CTX_DDL.set_attribute(PREFERENCE_NAME
ATTRIBUTE_NAME
ATTRIBUTE_VALUE
END;
/

=>
=>
=>

'my_lexer',
'printjoins',
'-,!');

Example 12–35 builds a CONTEXT index using the new my_lexer lexer preference. It
uses preference preference-case-mixed.
Example 12–35 CONTEXT Index on PURCHASE_ORDERS Table, Mixed Case
CREATE INDEX po_index ON purchase_orders(doc)
INDEXTYPE IS CTXSYS.CONTEXT
PARAMETERS('lexer my_lexer section group CTXSYS.PATH_SECTION_GROUP');

Example 12–33 returns no rows, because "HURRY" in text_query no longer matches
"Hurry" in the purchaseOrder. Example 12–36 returns one row, because the text_
query term "Hurry" exactly matches the word "Hurry" in the purchaseOrder.
Example 12–36 CONTAINS: Mixed (Exact) Case Matching
SELECT id FROM purchase_orders
WHERE contains(doc, 'Hurry INPATH (/purchaseOrder/comment)') > 0;

Introduction to Section Groups
One of the choices you make when creating a CONTEXT index is section group. A
section group instance is based on a section group type. The section group type
specifies the kind of structure in your documents, and how to index (and therefore
search) that structure. The section group instance may specify which structure
elements are indexed. Most users either take the default section group or use a
predefined section group.
Choosing a Section Group Type The section group types useful in XML searching are:
■

PATH_SECTION_GROUP
Choose this when you want to use WITHIN, INPATH and HASPATH in queries, and
you want to be able to consider all sections to scope the query.

■

XML_SECTION_GROUP
Choose this when you want to use WITHIN, but not INPATH and HASPATH, in
queries, and you want to be able to consider only explicitly-defined sections to
scope the query. XML_SECTION_GROUP section group type supports FIELD
Full-Text Search Over XML Data 12-15

CONTAINS SQL Function

sections in addition to ZONE sections. In some cases FIELD sections offer
significantly better query performance.
■

AUTO_SECTION_GROUP
Choose this when you want to use WITHIN, but not INPATH and HASPATH, in
queries, and you want to be able to consider most sections to scope the query. By
default all sections are indexed (available for query restriction). You can specify
that some sections are not indexed (by defining STOP sections).

■

NULL_SECTION_GROUP
Choose this when defining no XML sections.

Other section group types include:
■

BASIC_SECTION_GROUP

■

HTML_SECTION_GROUP

■

NEWS_SECTION_GROUP

Oracle recommends that most users with XML full-text search requirements use
PATH_SECTION_GROUP. Some users might prefer XML_SECTION_GROUP with FIELD
sections. This choice generally gives better query performance and a smaller index, but
it is limited to documents with fielded structure (searchable nodes are all leaf nodes
that do not repeat).
See Also: Oracle Text Reference for a detailed description of the
XML_SECTION_GROUP section group type

Choosing a Section Group When choosing a section group to use with your index, you
can choose a supplied section group, take the default, or create a new section group
based on the section group type you have chosen.
There are supplied section groups for section group types PATH_SECTION_GROUP,
AUTO_SECTION_GROUP, and NULL_SECTION_GROUP. The supplied section groups
are owned by CTXSYS and have the same name as their section group types. For
example, the supplied section group of section group type PATH_SECTION_GROUP is
CTXSYS.PATH_SECTION_GROUP.
There is no supplied section group for section group type XML_SECTION_GROUP,
because a default XML_SECTION_GROUP would be empty and therefore meaningless.
If you want to use section group type XML_SECTION_GROUP, then you must create a
new section group and specify each node that you want to include as a section.
When you create a CONTEXT index on data of type XMLType, the default section group
is the supplied section group CTXSYS.PATH_SECTION_GROUP. If the data is
VARCHAR or CLOB, then the default section group is CTXSYS.NULL_SECTION_GROUP.
See Also: Oracle Text Reference for instructions on creating your
own section group

To associate a section group with an index, add section group 
 to the PARAMETERS string, as in Example 12–37.
Example 12–37 Simple CONTEXT Index on purchase_orders Table with Path Section
Group
CREATE INDEX po_index ON purchase_orders(doc)
INDEXTYPE IS CTXSYS.CONTEXT
PARAMETERS ('section group CTXSYS.PATH_SECTION_GROUP');

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ora:contains XQuery Function

ora:contains XQuery Function
Function ora:contains is an Oracle-defined XQuery (XPath) function for use in the
XQuery expression argument to SQL/XML functions XMLQuery, XMLTable, and
XMLExists.
When you use ora:contains you must also supply a namespace declaration that
maps prefix ora to the Oracle XML DB namespace,
xmlns:ora="http://xmlns.oracle.com/xdb".
Function ora:contains returns a number. It does not return a score. It returns a
positive number if the text_query matches the input_text. Otherwise it returns
zero.

Full-Text Search using XQuery Function ora:contains
The ora:contains argument text_query is a string that specifies the full-text
search. The ora:contains text_query is the same as the contains text_query,
with the following restrictions:
■

■

ora:contains text_query must not include any of the structure operators
WITHIN, INPATH, or HASPATH
ora:contains text_query can include the score weighting operator
weight(*), but weights are ignored

If you include any of the following in the ora:contains text_query, the query
cannot use a CONTEXT index:
■

Score-based operator MINUS (-) or threshold (>)

■

Selective, corpus-based expansion operator FUZZY (?) or soundex (!)
See Also:

"XPath Rewrite and CONTEXT Indexes" on page 12-23

Example 12–4 shows a full-text search using an arbitrary combination of Boolean
operators and $ (stemming).
See Also:
■

■

"Full-Text Search using SQL Function CONTAINS" on
page 12-5 for a description of full-text operators
Oracle Text Reference for a full list of the operators you can use in
contains and ora:contains

Matching rules are defined by the policy, policy_owner.policy_name. If policy_
owner is absent, then the policy owner defaults to the current user. If both policy_
name and policy_owner are absent, then the policy defaults to CTXSYS.DEFAULT_
POLICY_ORACONTAINS.

Restricting the Scope of an ora:contains Query
When you use ora:contains in an XPath expression, the scope is defined by
argument input_text. This argument is evaluated in the current XPath context. If
the result is a single text node or an attribute, then that node is the target of the
ora:contains search. If input_text does not evaluate to a single text node or an
attribute, an error is raised.

Full-Text Search Over XML Data 12-17

ora:contains XQuery Function

The policy determines the matching rules for ora:contains. The section group
associated with the default policy for ora:contains is of type NULL_SECTION_
GROUP.
ora:contains can be used anywhere in an XPath expression, and its input_text
argument can be any XPath expression that evaluates to a single text node or an
attribute.

Projecting the ora:contains Result
If you want to return only a part of each XML document, then use function XMLQuery
to project a node sequence, possibly applying XMLCast to the result to project the
scalar value of a node.
Example 12–38 returns the orderDate for each purchase order that has a comment
that contains the word "lawn".
Example 12–38 Using ora:contains with XMLQuery and XMLExists
SELECT XMLCast(XMLQuery(
'declare namespace ora = "http://xmlns.oracle.com/xdb"; (: :)
$d/purchaseOrder/@orderDate'
PASSING doc AS "d" RETURNING CONTENT)
AS DATE) "Order date"
FROM purchase_orders_xmltype
WHERE XMLExists(
'declare namespace ora = "http://xmlns.oracle.com/xdb"; (: :)
$d/purchaseOrder/comment
[ora:contains(text(), "($lawns AND wild) OR flamingo") > 0]'
PASSING doc AS "d");

Function XMLExists restricts the result to rows (documents) where the
purchaseOrder element includes some comment that contains the word "lawn".
Function XMLQuery then returns the value of attribute orderDate from those
purchaseOrder elements. Function XMLCast casts this result as a SQL DATE value.
If //comment had been extracted, then both comments from the sample document
would have been returned, not just the comment that matches the WHERE clause.
See Also: Example 12–26, "Scoping the Results of a CONTAINS
Query" on page 12-12

Policies for ora:contains Queries
The CONTEXT index on a column determines the semantics of contains queries on
that column. Because ora:contains does not rely on a supporting index, some other
means must be found to provide many of the same choices when doing
ora:contains queries. A policy is a collection of preferences that can be associated
with an ora:contains query to give the same sort of semantic control as the
indexing choices give to the contains user.

Introduction to Policies for ora:contains Queries
When using Oracle SQL function contains, indexing preferences affect the semantics
of the query. You create a preference using procedure CTX_DDL.create_
preference (or CTX_DDL.create_stoplist). You override default choices by
setting attributes of the new preference, using procedure CTX_DDL.set_attribute.
Then you use the preference in a CONTEXT index by including preference_type
preference_name in the PARAMETERS string of CREATE INDEX.

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ora:contains XQuery Function

See Also:

"CONTEXT Index Preferences" on page 12-14

Because ora:contains does not have a supporting index, a different mechanism is
needed to apply preferences to a query. That mechanism is a policy, consisting of a
collection of preferences, and it is used as a parameter to ora:contains.
Policy Example: Supplied Stoplist Example 12–39 creates a policy with an empty
stopwords list.
Example 12–39 Create a Policy to Use with ora:contains
BEGIN
CTX_DDL.create_policy(POLICY_NAME
STOPLIST
END;
/

=>
=>

'my_nostopwords_policy',
'CTXSYS.EMPTY_STOPLIST');

For simplicity, this policy consists of an empty stoplist, which is owned by user
CTXSYS. You could create a new stoplist to include in this policy, or you could reuse a
stoplist (or lexer) definition that you created for a CONTEXT index.
Refer to this policy in an ora:contains expression to search for all words, including
the most common ones (stopwords). Example 12–40 returns zero comments, because
"is" is a stopword by default and cannot be queried.
Example 12–40 Finding a Stopword using ora:contains
SELECT id FROM purchase_orders_xmltype
WHERE XMLExists(
'declare namespace ora = "http://xmlns.oracle.com/xdb"; (: :)
$d/purchaseOrder/comment[ora:contains(text(), "is") > 0]'
PASSING doc AS "d");

Example 12–41 uses the policy created in Example 12–39 to specify an empty stopword
list. This query finds "is" and returns 1 comment.
Example 12–41 Finding a Stopword using ora:contains and Policy my_nostopwords_
policy
SELECT id FROM purchase_orders_xmltype
WHERE XMLExists(
'declare namespace ora = "http://xmlns.oracle.com/xdb"; (: :)
$d/purchaseOrder/comment
[ora:contains(text(), "is", "MY_NOSTOPWORDS_POLICY") > 0]'
PASSING doc AS "d");

Example 12–41 uses policy my_nostopwords_policy. This policy was implicitly
named as all uppercase, in Example 12–39. Because XPath is case-sensitive, it must be
referred to in the XPath predicate using all uppercase: MY_NOSTOPWORDS_POLICY,
not my_nostopwords_policy.

Effect of Policies on ora:contains
The ora:contains policy affects the matching semantics of text_query. The
ora:contains policy may include a lexer, stoplist, wordlist preference, or any
combination of these. Other preferences that can be used to build a CONTEXT index are
not applicable to ora:contains. The effects of the preferences are as follows:
■

The wordlist preference tweaks the semantics of the stem operator.

Full-Text Search Over XML Data 12-19

ora:contains XQuery Function

■

■

The stoplist preference defines which words are too common to be indexed
(searchable).
The lexer preference defines how words are tokenized and matched. For example,
it defines which characters count as part of a word and whether matching is
case-sensitive.
See Also:
■

■

"Policy Example: Supplied Stoplist" on page 12-19 for an
example of building a policy with a predefined stoplist
"Policy Example: User-Defined Lexer" on page 12-20 for an
example of a case-sensitive policy

Policy Example: User-Defined Lexer When you search for a document that contains a
particular word, you usually want the search to be case-insensitive. If you do a search
that is case-sensitive, then you often miss some expected results. For example, if you
search for purchaseOrders that contain the phrase "baby monitor", then you would
not expect to miss our example document just because the phrase is written "Baby
Monitor".
Full-text searches with ora:contains are case-insensitive by default. Section names
and attribute names, however, are always case-sensitive.
If you want full-text searches to be case-sensitive, then you need to make that choice
when you create a policy. You can use this procedure:
1.

Create a preference using the procedure CTX_DDL.create_preference (or
CTX_DDL.create_stoplist).

2.

Override default choices in that preference object by setting attributes of the new
preference, using procedure CTX_DDL.set_attribute.

3.

Use the preference as a parameter to CTX_DDL.create_policy.

4.

Use the policy name as the third argument to ora:contains in a query.

Once you have created a preference, you can reuse it in other policies or in CONTEXT
index definitions. You can use any policy with any ora:contains query.
Example 12–42 returns 1 row, because "HURRY" in text_query matches "Hurry" in
the purchaseOrder with the default case-insensitive index.
Example 12–42 ora:contains, Default Case-Sensitivity
SELECT id FROM purchase_orders_xmltype
WHERE XMLExists(
'declare namespace ora = "http://xmlns.oracle.com/xdb"; (: :)
$d/purchaseOrder/comment[ora:contains(text(), "HURRY") > 0]'
PASSING doc AS "d");

Example 12–43 creates a new lexer preference my_lexer, with the attribute mixed_
case set to TRUE. It also sets printjoin characters to "-", "!" and ",". You can use
the same preferences for building CONTEXT indexes and for building policies.
See Also:

Oracle Text Reference for a full list of lexer attributes

Example 12–43 Create a Preference for Mixed Case
BEGIN
CTX_DDL.create_preference(PREFERENCE_NAME
OBJECT_NAME
12-20 Oracle XML DB Developer's Guide

=>
=>

'my_lexer',
'BASIC_LEXER');

ora:contains XQuery Function

CTX_DDL.set_attribute(PREFERENCE_NAME
ATTRIBUTE_NAME
ATTRIBUTE_VALUE
CTX_DDL.set_attribute(PREFERENCE_NAME
ATTRIBUTE_NAME
ATTRIBUTE_VALUE
END;
/

=>
=>
=>
=>
=>
=>

'MY_LEXER',
'MIXED_CASE',
'TRUE');
'my_lexer',
'printjoins',
'-,!');

Example 12–44 creates a new policy my_policy and specifies only the lexer. All other
preferences are defaulted. Example 12–44 uses preference-case-mixed.
Example 12–44 Create a Policy with Mixed Case (Case-Insensitive)
BEGIN
CTX_DDL.create_policy(POLICY_NAME
LEXER
END;
/

=> 'my_policy',
=> 'my_lexer');

Example 12–45 uses the new policy in a query. It returns no rows, because "HURRY" in
text_query no longer matches "Hurry" in the purchaseOrder.
Example 12–45 ora:contains, Case-Sensitive (1)
SELECT id FROM purchase_orders_xmltype
WHERE XMLExists(
'declare namespace ora = "http://xmlns.oracle.com/xdb"; (: :)
$d/purchaseOrder/comment
[ora:contains(text(), "HURRY", "my_policy") > 0]'
PASSING doc AS "d");

Example 12–46 returns one row, because the text_query term "Hurry" exactly
matches the text "Hurry" in the comment element.
Example 12–46 ora:contains, Case-Sensitive (2)
SELECT id FROM purchase_orders_xmltype
WHERE XMLExists(
'declare namespace ora = "http://xmlns.oracle.com/xdb"; (: :)
$d/purchaseOrder/comment[ora:contains(text(), "Hurry") > 0]'
PASSING doc AS "d");

Policy Defaults
The policy argument to ora:contains is optional. If it is omitted, then the query
uses the default policy CTXSYS.DEFAULT_POLICY_ORACONTAINS.
When you create a policy for use with ora:contains, you do not need to specify
every preference. In Example 12–44 on page 12-21, for example, only the lexer
preference was specified. For the preferences that are not specified, CREATE_POLICY
uses the default preferences:
■

CTXSYS.DEFAULT_LEXER

■

CTXSYS.DEFAULT_STOPLIST

■

CTXSYS.DEFAULT_ WORDLIST

Creating a policy follows copy semantics for preferences and their attributes, just as
creating a CONTEXT index follows copy semantics for index metadata.

Full-Text Search Over XML Data 12-21

ora:contains XQuery Function

Performance of ora:contains
The ora:contains XPath function does not depend on a supporting index.
ora:contains is very flexible. But if you use it to search across large amounts of data
without an index, then it can also be resource-intensive. This section shows how to get
the best performance from queries that include XPath expressions with XPath function
ora:contains.
Function-based indexes can also be very effective in
speeding up XML queries, but they are not generally applicable to
Text queries.

Note:

The examples in this section use table purchase_orders_xmltype_big. This has
the same table structure and XML schema as purchase_orders_xmltype, but it has
around 1,000 rows. Each row has a unique ID (in column id), and some different text
in /purchaseOrder/items/item/comment. Where an execution plan is shown, it
was produced using the SQL*Plus command AUTOTRACE. Execution plans can also be
produced using SQL commands TRACE and TKPROF. A description of commands
AUTOTRACE, trace and tkprof is outside the scope of this chapter.
This section contains these topics:
■

Use a Primary Filter in the Query

■

XPath Rewrite and CONTEXT Indexes

Use a Primary Filter in the Query
Because ora:contains is relatively costly to process, Oracle recommends that you
write queries that include a primary filter wherever possible. This minimizes the
number of rows processed by ora:contains.
Example 12–47 examines each row in a table (a full table scan), as shown by the
execution plan. In this example, ora:contains is evaluated for each row.
Example 12–47 ora:contains in Large Table
SELECT id FROM purchase_orders_xmltype_big
WHERE XMLExists(
'declare namespace ora = "http://xmlns.oracle.com/xdb"; (: :)
$d/purchaseOrder/comment[ora:contains(text(), "constitution") > 0]'
PASSING doc AS "d");
Execution Plan
-----------------------------------------------------------------------------------------------| Id | Operation
| Name
|Rows|Bytes|Cost(%CPU)| Time|
-----------------------------------------------------------------------------------------------|
0| SELECT STATEMENT
|
| 32|64480|686(38)|00:00:09|
|* 1| FILTER
|
|
|
|
|
|
|
2|TABLE ACCESS FULL
|PURCHASE_ORDERS_XMLTYPE_BIG|1161|2284K| 140(3)|00:00:02|
|* 3|COLLECTION ITERATOR PICKLER FETCH| XMLSEQUENCEFROMXMLTYPE
|
|
|
|
|
-----------------------------------------------------------------------------------------------Predicate Information (identified by operation id):
--------------------------------------------------1 - filter( EXISTS (SELECT 0 FROM TABLE() "KOKBF$" WHERE
SYS_XMLCONTAINS(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(SYS_XQEXTRACT(SYS_XQCON2SEQ(VALUE(KOKBF$)),
'/comment/text()'),1,50),50,1,0),'constitution')>0))
3 - filter(SYS_XMLCONTAINS(SYS_XQ_UPKXML2SQL(SYS_XQEXVAL(SYS_XQEXTRACT(SYS_XQCON2SEQ(VALUE(KOKBF$)),
'/comment/text()'),1,50),50,1,0),'constitution')>0)
Note

12-22 Oracle XML DB Developer's Guide

ora:contains XQuery Function

----- dynamic sampling used for this statement

If you create an index on column id, as shown in Example 12–48, and you add a
selective predicate id to the query, as shown in Example 12–49, then index id drives
the execution, as shown in the execution plan. Function ora:contains is then
executed only for the rows where id is less than 5.
Example 12–48 B-tree Index on ID
CREATE INDEX id_index ON purchase_orders_xmltype_big(id);
Example 12–49 ora:contains in Large Table, with Additional Predicate
SELECT id FROM purchase_orders_xmltype_big
WHERE XMLExists(
'declare namespace ora = "http://xmlns.oracle.com/xdb"; (: :)
$d/purchaseOrder/comment[ora:contains(text(), "constitution") > 0]'
PASSING doc AS "d")
AND id > 5;
Execution Plan
----------------------------------------------------------------------------------------------| Id | Operation
| Name
|Rows| Bytes |Cost(%CPU)| Time|
----------------------------------------------------------------------------------------------|
0 | SELECT STATEMENT
|
| 1 | 2015 |8 (13)|00:00:01|
|* 1 | TABLE ACCESS BY INDEX ROWID|PURCHASE_ORDERS_XMLTYPE_BIG| 1 | 2015 |8 (13)|00:00:01|
|* 2 |
INDEX RANGE SCAN
|ID_INDEX
| 10 |
|2
(0)|00:00:01|
----------------------------------------------------------------------------------------------Predicate Information (identified by operation id):
--------------------------------------------------1 - filter(EXISTSNODE(SYS_MAKEXML("PURCHASE_ORDERS_XMLTYPE_BIG"."SYS_NC00003$
"),'/purchaseOrder/items/item/comment[ora:contains(text(), "constitution") >
0]','xmlns:ora="http://xmlns.oracle.com/xdb"')=1)
2 - access("ID">5)
Note
----- dynamic sampling used for this statement

XPath Rewrite and CONTEXT Indexes
Oracle Database can sometimes optimize a query that makes use of an XPath
expression. This XPath rewriting is done automatically as part of query optimization.
Although Oracle XQuery function ora:contains does not rely on a supporting
index, when XPath rewrite occurs ora:contains can often make use of an existing
CONTEXT index for better performance.
See Also:
■

■

"Automatic Rewriting of XQuery and XPath Expressions" on
page 1-20 for more on the benefits of XPath rewrite
Chapter 8, "XPath Rewrite for Structured Storage" for a full
discussion of XPath rewrite for object-relational storage

Example 12–50 ora:contains Search for "electric"
SELECT id FROM purchase_orders_xmltype
WHERE XMLExists(
Full-Text Search Over XML Data 12-23

ora:contains XQuery Function

'declare namespace ora = "http://xmlns.oracle.com/xdb"; (: :)
$d/purchaseOrder/items/item/comment
[ora:contains(text(), "electric") > 0]'
PASSING doc AS "d");

A naive evaluation of the XPath expression in Example 12–50 would test each cell in
column doc to see if it matches that expression.
But if doc is XML schema-based, and the purchaseOrder documents are physically
stored in object-relational tables, then it makes sense to go straight to column comment
(if such a column exists) and test each cell there to see if it matches "electric".
If the first argument to ora:contains maps to a single relational column, then
ora:contains can be applied to that column, instead of applying the complete
XPath expression to the entire XML document. Even if there are no indexes involved,
this can significantly improve query performance.
If you are using ora:contains with a text node or an attribute that maps to a
column that has a CONTEXT index then that index can sometimes be applied to the
data in the underlying column. The following conditions must both be true, in order
for a CONTEXT index to be used with object-relational XMLType data.
■

■

The ora:contains target (input_text) must be either a single text node whose
parent node maps to a column or an attribute that maps to a column. The column
must be a single relational column (possibly in an ordered collection table).
As noted in "Policies for ora:contains Queries" on page 12-18, the indexing choices
(for contains) and policy choices (for ora:contains) affect the semantics of
queries. A simple mismatch might be that the index-based contains would do a
case-sensitive search, while ora:contains specifies a case-insensitive search. To
ensure that the ora:contains and the rewritten contains have the same
semantics, the ora:contains policy must exactly match the index choices of the
CONTEXT index.

Both the ora:contains policy and the CONTEXT index must also use the NULL_
SECTION_GROUP section group type. The default section group for an
ora:contains policy is ctxsys.NULL_SECTION_GROUP.
Finally, the CONTEXT index is generally asynchronous. If you add a new document
that contains the word "dog", but do not synchronize the CONTEXT index, then a
contains query for "dog" does not return that document. But an ora:contains
query against the same data does. To ensure that the ora:contains and the
rewritten contains always return the same results, build the CONTEXT index with
the TRANSACTIONAL keyword in the PARAMETERS string.
See Also: Oracle Text Reference for information about creating a
CONTEXT index that is transactional using ALTER INDEX with
parameter TRANSACTIONAL

A query with XMLQuery, XMLTable or XMLExists, where the XPath includes
ora:contains, can be considered for XPath rewrite if the ora:contains policy
exactly matches the index choices of the CONTEXT index and if either of these
conditions is true:
■

The XML data is stored object-relationally; the first ora:contains argument
(input_text) is either a single text node whose parent node maps to a single
relational column or an attribute that maps to a single relational column; there is a
transactional CONTEXT index on that column.

12-24 Oracle XML DB Developer's Guide

Text Path BNF Specification

■

The XML data is binary XML that is indexed by an XMLIndex index, and there is a
CONTEXT index on either the path-table VALUE column of an unstructured
XMLIndex component or a scalar-value column of a structured XMLIndex
component.
If the CONTEXT index is non-transactional then you must also use XQuery
extension-expression pragma ora:use_text_index, to force the use of the
CONTEXT index. Example 12–51 illustrates this.

Example 12–51 Using XQuery Pragma ora:use_text_index with ora:contains
CREATE INDEX po_otext_ix ON my_path_table (VALUE) INDEXTYPE IS CTXSYS.CONTEXT;
EXPLAIN PLAN FOR
SELECT DISTINCT XMLCast(XMLQuery('$p/PurchaseOrder/ShippingInstructions/address'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(256)) "Address"
FROM po_binxml po
WHERE XMLExists(
'$p/PurchaseOrder/ShippingInstructions/address
[(# ora:use_text_index #) {ora:contains(., "$(Fortieth)")} > 0]'
PASSING po.OBJECT_VALUE AS "p");
---------------------------------------------------------------------------------------------------------------| Id | Operation
| Name
| Rows | Bytes|Cost (%CPU)| Time
|
---------------------------------------------------------------------------------------------------------------|
0 | SELECT STATEMENT
|
|
1 | 3046 |
12 (17)|00:00:01|
|
1 | SORT GROUP BY
|
|
1 | 3524 |
|
|
|* 2 |
TABLE ACCESS BY INDEX ROWID BATCHED| MY_PATH_TABLE
|
2 | 7048 |
3
(0)|00:00:01|
|* 3 |
INDEX RANGE SCAN
| SYS89559_PO_XMLINDE_PIKEY_IX |
1 |
|
2
(0)|00:00:01|
|
4 | HASH UNIQUE
|
|
1 | 3046 |
12 (17)|00:00:01|
|
5 |
NESTED LOOPS
|
|
1 | 3046 |
8 (13)|00:00:01|
|
6 |
SORT UNIQUE
|
|
1 | 3034 |
6
(0)|00:00:01|
|* 7 |
TABLE ACCESS BY INDEX ROWID
| MY_PATH_TABLE
|
1 | 3034 |
6
(0)|00:00:01|
|* 8 |
DOMAIN INDEX
| PO_OTEXT_IX
|
|
|
4
(0)|00:00:01|
|
9 |
TABLE ACCESS BY USER ROWID
| PO_BINXML
|
1 |
12 |
1
(0)|00:00:01|
---------------------------------------------------------------------------------------------------------------Predicate Information (identified by operation id):
--------------------------------------------------2
3
7
8

-

filter(SYS_XMLI_LOC_ISNODE("SYS_P3"."LOCATOR")=1)
access("SYS_P3"."RID"=:B1 AND "SYS_P3"."PATHID"=HEXTORAW('6F7F'))
filter("SYS_P1"."PATHID"=HEXTORAW('6F7F') AND SYS_XMLI_LOC_ISNODE("SYS_P1"."LOCATOR")=1)
access("CTXSYS"."CONTAINS"("SYS_P1"."VALUE",'$(Fortieth)')>0)

Note
----- dynamic sampling used for this statement (level=2)
28 rows selected.

Text Path BNF Specification
HasPathArg

::=
|

InPathArg
LocationPath

::=
::=
|

AbsoluteLocationPath ::=
|
RelativeLocationPath ::=

LocationPath
EqualityExpr
LocationPath
RelativeLocationPath
AbsoluteLocationPath
("/" RelativeLocationPath)
("//" RelativeLocationPath)
Step

Full-Text Search Over XML Data 12-25

Support for Full-Text XML Examples

|
|
Step

::=
|
|
|
|

Predicate

::=

OrExpr

::=

AndExpr

::=

BooleanExpr

::=

|
|
|
|
|
|
EqualityExpr

::=
|
|
|
|
|

Literal

::=

NCName
NCNameChar

::=
::=

|

|
|
|
|
Letter
Digit
Dot
Dash
Underscore

::=
::=
::=
::=
::=

(RelativeLocationPath "/" Step)
(RelativeLocationPath "//" Step)
("@" NCName)
NCName
(NCName Predicate)
Dot
"*"
("[" OrExp "]")
("[" Digit+ "]")
AndExpr
(OrExpr "or" AndExpr)
BooleanExpr
(AndExpr "and" BooleanExpr)
RelativeLocationPath
EqualityExpr
("(" OrExpr ")")
("not" "(" OrExpr ")")
(RelativeLocationPath "=" Literal)
(Literal "=" RelativeLocationPath)
(RelativeLocationPath "=" Literal)
(Literal "!=" RelativeLocationPath)
(RelativeLocationPath "=" Literal)
(Literal "!=" RelativeLocationPath)
(DoubleQuote [~"]* DoubleQuote)
(SingleQuote [~']* SingleQuote)
(Letter | Underscore) NCNameChar*
Letter
Digit
Dot
Dash
Underscore
([a-z] | [A-Z])
[0-9]
"."
"-"
"_"

Support for Full-Text XML Examples
This section contains these topics:
■

Purchase-Order XML Document, po001.xml

■

CREATE TABLE Statements

■

Purchase-Order XML Schema for Full-Text Search Examples

Purchase-Order XML Document, po001.xml
Example 12–52 Purchase Order XML Document, po001.xml



Alice Smith
123 Maple Street
Mill Valley
CA

12-26 Oracle XML DB Developer's Guide

Support for Full-Text XML Examples

90952


Robert Smith
8 Oak Avenue
Old Town
PA
95819

Hurry, my lawn is going wild!


Lawnmower
1
148.95
Confirm this is electric


Baby Monitor
1
39.98
1999-05-21




CREATE TABLE Statements
Example 12–53 Create Table PURCHASE_ORDERS
CREATE TABLE purchase_orders (id NUMBER, doc VARCHAR2(4000));
INSERT INTO purchase_orders (id, doc)
VALUES (1,
'


Alice Smith
123 Maple Street
Mill Valley
CA
90952


Robert Smith
8 Oak Avenue
Old Town
PA
95819

Hurry, my lawn is going wild!


Lawnmower
1
148.95
Confirm this is electric

Full-Text Search Over XML Data 12-27

Support for Full-Text XML Examples



Baby Monitor
1
39.98
1999-05-21


');
COMMIT;
Example 12–54 Create Table PURCHASE_ORDERS_XMLTYPE
CREATE TABLE purchase_orders_xmltype (id

NUMBER, doc XMLType);

INSERT INTO purchase_orders_xmltype (id, doc)
VALUES (1,
XMLTYPE ('


Alice Smith
123 Maple Street
Mill Valley
CA
90952


Robert Smith
8 Oak Avenue
Old Town
PA
95819

Hurry, my lawn is going wild!


Lawnmower
1
148.95
Confirm this is electric


Baby Monitor
1
39.98
1999-05-21


'));
COMMIT;
Example 12–55 Create Table PURCHASE_ORDERS_XMLTYPE_TABLE
CREATE TABLE purchase_orders_xmltype_table OF XMLType;
INSERT INTO purchase_orders_xmltype_table
VALUES (
XMLType ('
12-28 Oracle XML DB Developer's Guide

Support for Full-Text XML Examples



Alice Smith
123 Maple Street
Mill Valley
CA
90952


Robert Smith
8 Oak Avenue
Old Town
PA
95819

Hurry, my lawn is going wild!


Lawnmower
1
148.95
Confirm this is electric


Baby Monitor
1
39.98
1999-05-21


'));
COMMIT;

Purchase-Order XML Schema for Full-Text Search Examples
Example 12–56 Purchase-Order XML Schema for Full-Text Search Examples




Purchase order schema for Example.com.
Copyright 2000 Example.com. All rights reserved.














Full-Text Search Over XML Data 12-29

Support for Full-Text XML Examples









































12-30 Oracle XML DB Developer's Guide

Part III
Using XMLType APIs
Part III of this manual introduces you to ways you can use Oracle XML DB XMLType
PL/SQL, Java, C APIs, and Oracle Data Provider for .NET (ODP.NET) to access and
manipulate XML data. It contains the following chapters:
■

Chapter 13, "PL/SQL APIs for XMLType"

■

Chapter 14, "PL/SQL Package DBMS_XMLSTORE"

■

Chapter 15, "Java DOM API for XMLType"

■

Chapter 16, "Using the C API for XML"

■

Chapter 17, "Using Oracle Data Provider for .NET with Oracle XML DB"

13
PL/SQL APIs for XMLType
This chapter describes the use of the APIs for XMLType in PL/SQL.
This chapter contains these topics:
■

Overview of PL/SQL APIs for XMLType

■

PL/SQL DOM API for XMLType (DBMS_XMLDOM)

■

PL/SQL Parser API for XMLType (DBMS_XMLPARSER)

■

PL/SQL XSLT Processor for XMLType (DBMS_XSLPROCESSOR)

■

PL/SQL Translation API for XMLType (DBMS_XMLTRANSLATIONS)

Overview of PL/SQL APIs for XMLType
This chapter describes the PL/SQL Application Program Interfaces (APIs) for
XMLType. These include the following:
■

PL/SQL Document Object Model (DOM) API for XMLType (package DBMS_
XMLDOM): For accessing XMLType objects. You can access both XML schema-based
and non-schema-based documents. Before database startup, you must specify the
read-from and write-to directories in file initialization.ORA. For example:
UTL_FILE_DIR=/mypath/insidemypath

The read-from and write-to files must be on the server file system.
A DOM is a tree-based object representation of an XML document in dynamic
memory. It enables programmatic access to its elements and attributes. The DOM
object and its interface is a W3C recommendation. It specifies the Document
Object Model of an XML document including APIs for programmatic access. DOM
views the parsed document as a tree of objects.
■

■

PL/SQL XML Parser API for XMLType (package DBMS_XMLPARSER): For
accessing the content and structure of XML documents.
PL/SQL XSLT Processor for XMLType (package DBMS_XSLPROCESSOR): For
transforming XML documents to other formats using XSLT.

API Features
The PL/SQL APIs for XMLType allow you to perform the following tasks:
■

Create XMLType tables, columns, and views

■

Construct XMLType instances from data encoded in different character sets.

PL/SQL APIs for XMLType 13-1

Overview of PL/SQL APIs for XMLType

■

Access XMLType data

■

Manipulate XMLType data
See Also:
■

"Oracle XML DB Features", for an overview of the Oracle
XML DB architecture and new features.

■

Chapter 4, "XMLType Operations"

■

Oracle Database PL/SQL Packages and Types Reference

Lazy Loading of XML Data (Lazy Manifestation)
Because XMLType provides a dynamic memory or virtual Document Object Model
(DOM), it can use a memory conserving process called lazy XML loading, also
sometimes referred to as lazy manifestation. This process optimizes memory usage by
only loading rows of data when they are requested. It throws away
previously-referenced sections of the document if memory usage grows too large. Lazy
XML loading supports highly scalable applications that have many concurrent users
needing to access large XML documents.

XMLType Data Type Supports XML Schema
The XMLType data type includes support for XML schemas. You can create an XML
schema and annotate it with mappings from XML to object-relational storage. To take
advantage of the PL/SQL DOM API, first create an XML schema and register it. Then,
when you create XMLType tables and columns, you can specify that these conform to
the registered XML schema.

XMLType Supports Data in Different Character Sets
XMLType instances can be created from data encoded in any Oracle-supported
character set by using the PL/SQL XMLType constructor or XMLType method
createXML(). The source XML data must be supplied using data type BFILE or
BLOB. The encoding of the data is specified through argument csid. When this
argument is zero (0), the encoding of the source data is determined from the XML
prolog, as specified in Appendix F of the XML 1.0 Reference.

AL32UTF8 is the Oracle Database character set that is
appropriate for XMLType data. It is equivalent to the IANA registered
standard UTF-8 encoding, which supports all valid XML characters.

Caution:

Do not confuse Oracle Database database character set UTF8 (no
hyphen) with database character set AL32UTF8 or with character
encoding UTF-8. Database character set UTF8 has been superseded by
AL32UTF8. Do not use UTF8 for XML data. Character set UTF8
supports only Unicode version 3.1 and earlier. It does not support all
valid XML characters. AL32UTF8 has no such limitation.
Using database character set UTF8 for XML data could potentially stop
a system or affect security negatively. If a character that is not supported
by the database character set appears in an input-document element
name, a replacement character (usually "?") is substituted for it. This
terminates parsing and raises an exception. It could cause an
irrecoverable error.

13-2 Oracle XML DB Developer's Guide

PL/SQL DOM API for XMLType (DBMS_XMLDOM)

PL/SQL DOM API for XMLType (DBMS_XMLDOM)
This section describes the PL/SQL DOM API for XMLType, DBMS_XMLDOM.
See Also: Oracle Database PL/SQL Packages and Types Reference for
descriptions of the individual DBMS_XMLDOM methods

Overview of the W3C Document Object Model (DOM) Recommendation
Skip this section if you are familiar with the generic DOM specifications recommended
by the World Wide Web Consortium (W3C).
The Document Object Model (DOM) recommended by the W3C is a universal API for
accessing the structure of XML documents. It was originally developed to formalize
Dynamic HTML, which is used for animation, interaction, and dynamic updating of
Web pages. DOM provides a language-neutral and platform-neutral object model for
Web pages and XML documents. DOM describes language-independent and
platform-independent interfaces to access and operate on XML components and
elements. It expresses the structure of an XML document in a universal,
content-neutral way. Applications can be written to dynamically delete, add, and edit
the content, attributes, and style of XML documents. DOM makes it possible to create
applications that work properly on all browsers, servers, and platforms.

Oracle XML Developer's Kit Extensions to the W3C DOM Standard
Oracle XML Developer's Kit (XDK) extends the W3C DOM API in various ways. All of
these extensions are supported by Oracle XML DB except those relating to client-side
operations that are not applicable in the database. This type of procedural processing
is available through the Simple API for XML (SAX) interface in the Oracle XML
Developer's Kit Java and C components.
See Also:

Oracle XML Developer's Kit Programmer's Guide

Supported W3C DOM Recommendations
All Oracle XML DB APIs for accessing and manipulating XML comply with standard
XML processing requirements as approved by the W3C. The PL/SQL DOM supports
Levels 1 and 2 from the W3C DOM specifications.
■

■

In Oracle9i release 1 (9.0.1), Oracle XML Developer's Kit for PL/SQL implemented
DOM Level 1.0 and parts of DOM Level 2.0.
In Oracle9i release 2 (9.2) and Oracle Database 10g release 1 (10.1), the PL/SQL
API for XMLType implements DOM Levels 1.0 and Level 2.0 Core, and is fully
integrated in the database through extensions to the XMLType API.

The following briefly describes each level:
■

■

DOM Level 1.0 – The first formal Level of the DOM specifications, completed in
October 1998. Level 1.0 defines support for XML 1.0 and HTML.
DOM Level 2.0 – Completed in November 2000, Level 2.0 extends Level 1.0 with
support for XML 1.0 with namespaces and adds support for Cascading Style
Sheets (CSS) and events (user-interface events and tree manipulation events), and
enhances tree manipulations (tree ranges and traversal mechanisms). CSS are a
simple mechanism for adding style (fonts, colors, spacing, and so on) to Web
documents.

PL/SQL APIs for XMLType 13-3

PL/SQL DOM API for XMLType (DBMS_XMLDOM)

Difference Between DOM and SAX
The generic APIs for XML can be classified in two main categories:
■
■

Tree-based. DOM is the primary generic tree-based API for XML.
Event-based. SAX (Simple API for XML) is the primary generic event-based
programming interface between an XML parser and an XML application.

DOM works by creating objects. These objects have child objects and properties, and
the child objects have child objects and properties, and so on. Objects are referenced
either by moving down the object hierarchy or by explicitly giving an HTML element
an ID attribute. For example:


Examples of structural manipulations are:
■

Reordering elements

■

Adding or deleting elements

■

Adding or deleting attributes

■

Renaming elements
See Also:
■

http://www.w3.org/DOM/ for information about DOM

■

http://www.saxproject.org/ for information about SAX

PL/SQL DOM API for XMLType (DBMS_XMLDOM): Features
Oracle XML DB extends the Oracle Database XML development platform beyond SQL
support for storage and retrieval of XML data. It lets you operate on XMLType
instances using DOM in PL/SQL, Java, and C.
The default action for the PL/SQL DOM API for XMLType (DBMS_XMLDOM) is to do the
following:
■

Produce a parse tree that can be accessed by DOM APIs.

■

Validate, if a DTD is found. Otherwise, do not validate.

■

Raise an application error if parsing fails.

DTD validation occurs when the object document is manifested. If lazy manifestation
is employed, then the document is validated when it is used.
The PL/SQL DOM API exploits a C-based representation of XML in the server and
operates on XML schema-based XML instances. The PL/SQL, Java, and C DOM APIs
for XMLType comply with the W3C DOM Recommendations to define and implement
structured storage of XML data in relational or object-relational columns and as
dynamic memory instances of XMLType. See "Preparing XML Data to Use the PL/SQL
DOM API for XMLType" on page 13-6, for a description of W3C DOM
Recommendations.

XML Schema Support
The PL/SQL DOM API for XMLType supports XML schema. Oracle XML DB uses
annotations within an XML schema as metadata to determine the structure of an XML
document and the mapping of the document to a database schema.

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PL/SQL DOM API for XMLType (DBMS_XMLDOM)

For backward compatibility and flexibility, the PL/SQL
DOM supports both XML schema-based documents and
non-schema-based documents.

Note:

After an XML schema is registered with Oracle XML DB, the PL/SQL DOM API for
XMLType builds a tree representation of an associated XML document in dynamic
memory as a hierarchy of node objects, each with its own specialized interfaces. Most
node object types can have child node types, which in turn implement additional,
more specialized interfaces. Nodes of some node types can have child nodes of various
types, while nodes of other node types must be leaf nodes, which do not have child
nodes.

Enhanced Performance
Oracle XML DB uses DOM to provide a standard way to translate data between XML
and multiple back-end data sources. This eliminates the need to use separate XML
translation techniques for the different data sources in your environment. Applications
needing to exchange XML data can use a single native XML database to cache XML
documents. Oracle XML DB can thus speed up application performance by acting as
an intermediate cache between your Web applications and your back-end data
sources, whether they are in relational databases or file systems.
See Also:

Chapter 15, "Java DOM API for XMLType"

Designing End-to-End Applications using Oracle XML Developer's Kit and Oracle
XML DB
When you build applications based on Oracle XML DB, you do not need the
additional components in Oracle XML Developer's Kit. However, you can use Oracle
XML Developer's Kit components with Oracle XML DB to deploy a full suite of
XML-enabled applications that run end-to-end. You can use features in Oracle XML
Developer's Kit for:
■

■

Simple API for XML (SAX) interface processing. SAX is an XML standard interface
provided by XML parsers and used by procedural and event-based applications.
DOM interface processing, for structural and recursive object-based processing.

Oracle XML Developer's Kit contain the basic building blocks for creating applications
that run on a client, in a browser or a plug-in. Such applications typically read,
manipulate, transform and view XML documents. To provide a broad variety of
deployment options, Oracle XML Developer's Kit is available for Java, C, and C++.
Oracle XML Developer's Kit is fully supported and comes with a commercial
redistribution license.
Oracle XML Developer's Kit for Java consists of these components:
■

■

■

■

XML Parsers – Creates and parses XML using industry standard DOM and SAX
interfaces. Supports Java, C, C++, and the Java API for XML Processing (JAXP).
XSL Processor – Transforms or renders XML into other text-based formats such as
HTML. Supports Java, C, and C++.
XML Schema Processor – Uses XML simple and complex data types. Supports
Java, C, and C++.
XML Class Generator, Oracle JAXB Class Generator – Automatically generate
C++ and Java classes, respectively, from DTDs and XML schemas, to send XML

PL/SQL APIs for XMLType 13-5

PL/SQL DOM API for XMLType (DBMS_XMLDOM)

data from Web forms or applications. Class generators accept an input file and
create a set of output classes that have corresponding functionality. For the XML
Class Generator, the input file is a DTD, and the output is a series of classes that
can be used to create XML documents conforming with the DTD.
■

■

■
■

■

XML SQL Utility – Generates XML documents, DTDs, and XML schemas from
SQL queries. Supports Java.
TransX Utility – Loads data encapsulated in XML into the database. Has
additional functionality useful for installations.
XML Pipeline Processor – Invokes Java processes through XML control files.
XSLT VM and Compiler – Provides a high-performance C-based XSLT
transformation engine that uses compiled style sheets.
XML Java Beans – Parses, transforms, compares, retrieves, and compresses XML
documents using Java components.
See Also:

Oracle XML Developer's Kit Programmer's Guide

Preparing XML Data to Use the PL/SQL DOM API for XMLType
To prepare data for using PL/SQL DOM APIs in Oracle XML DB:
1.

Create a standard XML schema.

2.

Annotate the XML schema with definitions for the SQL objects you use.

3.

Register the XML schema, to generate the necessary database mappings.

You can then do any of the following:
■

■
■

Use XMLType views to wrap existing relational or object-relational data in XML
formats, making it available to your applications in XML form. See "Wrapping
Existing Data into XML with XMLType Views" on page 13-7.
Insert XML data into XMLType columns.
Use Oracle XML DB PL/SQL and Java DOM APIs to manipulate XML data stored
in XMLType columns and tables.

Defining an XML Schema Mapping to SQL Object Types
An XML schema must be registered before it can be referenced by an XML document.
When you register an XML schema, elements and attributes it declares are mapped to
attributes of corresponding SQL object types within the database.
After XML schema registration, XML documents that conform to the XML schema and
reference it can be managed by Oracle XML DB. Tables and columns for storing the
conforming documents can be created for root elements defined by the XML schema.
See Also:

Chapter 7, "XML Schema Storage and Query: Basic"

An XML schema is registered by using PL/SQL package DBMS_XMLSCHEMA and by
specifying the schema document and its schema-location URL. This URL is a name that
uniquely identifies the registered schema within the databas. It need not correspond to
any real location—in particular, it need not indicate where the schema document is
located.
The target namespace of the schema is another URL used in the XML schema. It
specifies a namespace for the XML-schema elements and types. An XML document

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PL/SQL DOM API for XMLType (DBMS_XMLDOM)

should specify both the namespace of the root element and the schema-location URL
identifying the schema that defines this element.
When documents are inserted into Oracle XML DB using path-based protocols such as
HTTP(S) and FTP, the XML schema to which the document conforms is registered
implicitly, provided its name and location are specified and it has not yet been
registered.
See Also: Oracle Database PL/SQL Packages and Types Reference
descriptions of the individual DBMS_XMLSCHEMA methods

DOM Fidelity for XML Schema Mapping
Elements and attributes declared within the XML schema get mapped to separate
attributes of the corresponding SQL object type. Other information encoded in an XML
document, such as comments, processing instructions, namespace declarations and
prefix definitions, and whitespace, is not represented directly.
To store this additional information, binary attribute SYS_XDBPD$ is present in all
generated SQL object types. This database attribute stores all information in the
original XML document that is not stored using the other database attributes.
Retaining this accessory information ensures DOM fidelity for XML documents stored
in Oracle XML DB: an XML document retrieved from the database is identical to the
original document that was stored.
Note: In this book, the SYS_XDBPD$ attribute has been omitted
from most examples, for simplicity. However, the attribute is
always present in SQL object types generated by schema
registration.

Wrapping Existing Data into XML with XMLType Views
To make existing relational and object-relational data available to your XML
applications, you can create XMLType views, wrapping the data in an XML format.
You can then access this XML data using the PL/SQL DOM API.
After you register an XML schema containing annotations that represent the mapping
between XML types and SQL object types, you can create an XMLType view that
conforms to the XML schema.
See Also:

Chapter 19, "XMLType Views"

DBMS_XMLDOM Methods Supported
All DBMS_XMLDOM methods are supported by Oracle XML DB, with the exception of the
following:
■

writeExternalDTDToFile()

■

writeExternalDTDToBuffer()

■

writeExternalDTDToClob()
See Also: Oracle Database PL/SQL Packages and Types Reference for
descriptions of the individual DBMS_XMLDOM methods

PL/SQL APIs for XMLType 13-7

PL/SQL DOM API for XMLType (DBMS_XMLDOM)

PL/SQL DOM API for XMLType: Node Types
In the DOM specification, the term "document" is used to describe a container for
many different kinds of information or data, which the DOM objectifies. The DOM
specifies the way elements within an XML document container are used to create an
object-based tree structure and to define and expose interfaces to manage and use the
objects stored in XML documents. Additionally, the DOM supports storage of
documents in diverse systems.
When a request such as getNodeType(myNode) is given, it returns myNodeType,
which is the node type supported by the parent node. These constants represent the
different types that a node can adopt:
■

ELEMENT_NODE

■

ATTRIBUTE_NODE

■

TEXT_NODE

■

CDATA_SECTION_NODE

■

ENTITY_REFERENCE_NODE

■

ENTITY_NODE

■

PROCESSING_INSTRUCTION_NODE

■

COMMENT_NODE

■

DOCUMENT_NODE

■

DOCUMENT_TYPE_NODE

■

DOCUMENT_FRAGMENT_NODE

■

NOTATION_NODE

Table 13–1 shows the node types for XML and HTML and the allowed corresponding
children node types.
Table 13–1

XML and HTML DOM Node Types and Their Child Node Types

Node Type

Children Node Types

Document

Element (maximum of one), ProcessingInstruction, Comment,
DocumentType (maximum of one)

DocumentFragment

Element, ProcessingInstruction, Comment, Text, CDATASection,
EntityReference

DocumentType

No children

EntityReference

Element, ProcessingInstruction, Comment, Text, CDATASection,
EntityReference

Element

Element, Text, Comment, ProcessingInstruction, CDATASection,
EntityReference

Attr

Text, EntityReference

ProcessingInstruction

No children

Comment

No children

Text

No children

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PL/SQL DOM API for XMLType (DBMS_XMLDOM)

Table 13–1 (Cont.) XML and HTML DOM Node Types and Their Child Node Types
Node Type

Children Node Types

CDATASection

No children

Entity

Element, ProcessingInstruction, Comment, Text, CDATASection,
EntityReference

Notation

No children

Oracle XML DB DOM API for XMLType also specifies these interfaces:
■

■

A NodeList interface to handle ordered lists of Nodes, for example:
–

The children of a Node

–

Elements returned by method getElementsByTagName() of the element
interface

A NamedNodeMap interface to handle unordered sets of nodes, referenced by
their name attribute, such as the attributes of an element.

Working with XML Schema-Based Data
Oracle Database has several extensions for character-set conversion and input and
output to and from a file system. PL/SQL API for XMLType is optimized to operate on
XML schema-based XML instances. Function newDOMDocument constructs a DOM
document handle, given an XMLType value.
A typical usage scenario would be for a PL/SQL application to:
1.

Fetch or construct an XMLType instance

2.

Construct a DOMDocument node over the XMLType instance

3.

Use the DOM API to access and manipulate the XML data
Note: For DOMDocument, node types represent handles to XML
fragments but do not represent the data itself.

For example, if you copy a node value, DOMDocument clones the
handle to the same underlying data. Any data modified by one of
the handles is visible when accessed by the other handle. The
XMLType value from which the DOMDocument handle is
constructed is the data, and reflects the results of all DOM
operations on it.

DOM NodeList and NamedNodeMap Objects
Changes to the underlying document structure are reflected in all relevant NodeList
and NamedNodeMap objects.
For example, if a DOM user gets a NodeList object containing the children of an
element, and then subsequently adds more children to that element (or removes
children, or modifies them), then those changes are automatically propagated in the
NodeList, without additional action from the user. Likewise, changes to a node in the
tree are propagated throughout all references to that node in NodeList and
NamedNodeMap objects.
The interfaces: Text, Comment, and CDATASection, all inherit from the
CharacterData interface.
PL/SQL APIs for XMLType 13-9

PL/SQL DOM API for XMLType (DBMS_XMLDOM)

Using the PL/SQL DOM API for XMLType (DBMS_XMLDOM)
Figure 13–1 illustrates the use of PL/SQL DOM API for XMLType (DBMS_XMLDOM).
You can create a DOM document (DOMDocument) from an existing XMLType or as an
empty document.
1.

The newDOMDocument procedure processes the XMLType instance or empty
document. This creates a DOMDocument instance.

2.

You can use DOM API PL/SQL methods such as createElement(),
createText(), createAttribute(), and createComment() to traverse and
extend the DOM tree.

3.

The results of PL/SQL methods such as DOMElement() and DOMText() can also
be passed to PL/SQL function makeNode to obtain the DOMNode interface.

Figure 13–1 Using the PL/SQL DOM API for XMLType
Createxml

Select Statement

XMLType

newDOMDocument

newDOMDocument
(Empty
document)

DOMDocument
CreateElement

CreateTextNode

DOMElement
Interface

CreateAttribute

DOMText
Interface

CreateComment

DOMAttibute
Interface

...

DOMComment
Interface

makeNode

DOMNode Interface

PL/SQL DOM API for XMLType – Examples
This section presents examples of using the PL/SQL DOM API for XMLType.
Remember to call procedure freeDocument for each DOMDocument instance, when
you are through with the instance. This procedure frees the document and all of its
nodes. You can still access XMLType instances on which DOMDocument instances were
built, even after the DOMDocument instances have been freed.
Example 13–1 creates a hierarchical, representation of an XML document in dynamic
memory: a DOM document.
Example 13–1

Creating and Manipulating a DOM Document

CREATE TABLE person OF XMLType;
DECLARE

13-10 Oracle XML DB Developer's Guide

PL/SQL DOM API for XMLType (DBMS_XMLDOM)

var
XMLType;
doc
DBMS_XMLDOM.DOMDocument;
ndoc
DBMS_XMLDOM.DOMNode;
docelem
DBMS_XMLDOM.DOMElement;
node
DBMS_XMLDOM.DOMNode;
childnode DBMS_XMLDOM.DOMNode;
nodelist DBMS_XMLDOM.DOMNodelist;
buf
VARCHAR2(2000);
BEGIN
var := XMLType('ramesh');
-- Create DOMDocument handle
doc
:= DBMS_XMLDOM.newDOMDocument(var);
ndoc
:= DBMS_XMLDOM.makeNode(doc);
DBMS_XMLDOM.writeToBuffer(ndoc, buf);
DBMS_OUTPUT.put_line('Before:'||buf);
docelem := DBMS_XMLDOM.getDocumentElement(doc);
-- Access element
nodelist := DBMS_XMLDOM.getElementsByTagName(docelem, 'NAME');
node := DBMS_XMLDOM.item(nodelist, 0);
childnode := DBMS_XMLDOM.getFirstChild(node);
-- Manipulate element
DBMS_XMLDOM.setNodeValue(childnode, 'raj');
DBMS_XMLDOM.writeToBuffer(ndoc, buf);
DBMS_OUTPUT.put_line('After:'||buf);
DBMS_XMLDOM.freeDocument(doc);
INSERT INTO person VALUES (var);
END;
/

This produces the following output:
Before:
ramesh

After:
raj


This query confirms that the data has changed:
SELECT * FROM person;
SYS_NC_ROWINFO$
--------------
raj

1 row selected.

Example 13–1 uses a handle to the DOM document to manipulate it: print it, change
part of it, and print it again after the change. Manipulating the DOM document by its
handle also indirectly affects the XML data represented by the document, so that
querying that data after the change shows the changed result.

PL/SQL APIs for XMLType 13-11

PL/SQL DOM API for XMLType (DBMS_XMLDOM)

The DOM document is created from an XMLType variable using PL/SQL function
newDOMDocument. The handle to this document is created using function makeNode.
The document is written to a VARCHAR2 buffer using function writeToBuffer, and
the buffer is printed using DBMS_OUTPUT.put_line.
After manipulating the document using various DBMS_XMLDOM procedures, the
(changed) data in the XMLType variable is inserted into a table and queried, showing
the change. It is only when the data is inserted into a database table that it becomes
persistent. Until then, it exists in memory only. This persistence is demonstrated by the
fact that the database query is made after the document (DOMDocument instance) has
been freed from dynamic memory.
Example 13–2 creates an empty DOM document, and then adds an element node
() to the document. DBMS_XMLDOM API node procedures are used to obtain the
name (), value (NULL), and type (1 = element node) of the element node.
Example 13–2

Creating an Element Node and Obtaining Information About It

DECLARE
doc
DBMS_XMLDOM.DOMDocument;
elem DBMS_XMLDOM.DOMElement;
nelem DBMS_XMLDOM.DOMNode;
BEGIN
doc := DBMS_XMLDOM.newDOMDocument;
elem := DBMS_XMLDOM.createElement(doc,
nelem := DBMS_XMLDOM.makeNode(elem);
DBMS_OUTPUT.put_line('Node name = ' ||
DBMS_OUTPUT.put_line('Node value = '||
DBMS_OUTPUT.put_line('Node type = ' ||
DBMS_XMLDOM.freeDocument(doc);
END;
/

'ELEM');
DBMS_XMLDOM.getNodeName(nelem));
DBMS_XMLDOM.getNodeValue(nelem));
DBMS_XMLDOM.getNodeType(nelem));

This produces the following output:
Node name = ELEM
Node value =
Node type = 1

Large Node Handling using DBMS_XMLDOM
Prior to Oracle Database 11g Release 1 (11.1), each text node or attribute value
processed by Oracle XML DB was limited in size to 64 K bytes. Starting with release
11.1, this restriction no longer applies.
To overcome this size limitation and allow nodes to contain graphics files, PDF files,
and multibyte character encodings, the following abstract streams are available. These
abstract PL/SQL streams are analogous to the corresponding Java streams. Each input
stream has an associated writer, or data producer, and each output stream has an
associated reader, or data consumer.
1.

Binary Input Stream: This provides the data consumer with read-only access to
source data, as a sequential (non-array) linear space of bytes. The consumer has
iterative read access to underlying source data (whatever representation) in binary
format, that is, read access to source data in unconverted, "raw" format. The
consumer sees a sequence of bytes as they exist in the node. There is no
specification of the format or representation of the source data. In particular, there
is no associated character set.

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PL/SQL DOM API for XMLType (DBMS_XMLDOM)

2.

Binary Output Stream: This provides the data producer with write-only access to
target data as a sequential (non-array) linear space of bytes. The producer has
iterative write access to target data in binary format, that is, write access to target
data in pure binary format with no data semantics at all. The producer passes a
sequence of bytes and the target data is replaced by these bytes. No data
conversion occurs.

3.

Character Input Stream: This provides the data consumer iterative read-only
access to source data as a sequential (non-array) linear space of characters,
independent of the representation and format of the source data. Conversion of
the source data may or may not occur.

4.

Character Output Stream: This provides the data producer with iterative
write-only access to target data as a sequential (non-array) linear space of
characters. The producer passes a sequence of characters and the target data is
replaced by this sequence of characters. Conversion of the passed data may or may
not occur.

Each of the input streams has the following abstract methods: open, read, and close.
Each of the output streams has the following abstract methods: open, write, flush, and
close. For output streams, you must close the stream before any nodes are physically
written.
There are four general node access models, for reading and writing. Each access model
has both binary and character versions. Binary and character stream methods defined
on data type DOMNode realize these access models. Each access model is described in a
separate section, with an explanation of the PL/SQL functions and procedures in
package DBMS_XMLDOM that operate on large nodes.
■

Get-Push Model

■

Get-Pull Model

■

Set-Pull Model

■

Set-Push Model

For all except the get-push and set-pull access models (whether binary or character),
Oracle supplies a concrete stream that you can use (implicitly). For get-push and
set-pull, you must define a subtype of the abstract stream type that Oracle provides,
and you must implement its access methods (open, close, and so on). For get-push and
set-pull, you then instantiate your stream type and supply your stream as an argument
to the access method. So, for example, you would use my_
node.getNodeValueAsCharacterStream(my-stream) for get-push, but just
my_node.getNodeValueAsCharacterStream() for get-pull. The latter requires
no explicit stream argument, because the concrete stream supplied by Oracle is used.

PL/SQL APIs for XMLType 13-13

PL/SQL DOM API for XMLType (DBMS_XMLDOM)

When you access a character-data stream, the access
method you use determines the apparent character set of the nodes
accessed. If you use Java to access the stream, then the character set
seen by your Java program is UCS2 (or an application-specified
character set). If you use PL/SQL to access the stream, then the
character set seen by your PL/SQL program is the database-session
character set (or an application-specified character set). In all cases,
however, the XML data is stored in the database in the database
character set.

Note:

In the following descriptions, C1 is the character set of the node as
stored in the database, and C2 is the character set of the node as
seen by your program.

See Also:
■

■
■

■

"Handling Large Nodes using Java" on page 15-16 for information
on using Java with large nodes
Oracle Database PL/SQL Packages and Types Reference
Oracle Database XML Java API Reference for information about Java
functions for handling large nodes
Oracle Database XML C API Reference for information about C
functions for handling large nodes

Get-Push Model
To read a node value in this model, the application creates a binary output stream or
character output stream and passes this to Oracle XML DB. In this case, the source
data is the node value. Oracle XML DB populates the output stream by pushing node
data into the stream. If the stream is a character output stream, then the character set,
C2, is the session character set, and node data is converted, if necessary, from C1 to C2.
Additionally, the data type of the node may be any supported by Oracle XML DB and,
if the node data type is not character data then the node data is first converted to
character data in C2. If a binary output stream, the data type of the node must be RAW
or BLOB.
The procedures of the DBMS_XMLDOM package to be used for this case are:
PROCEDURE getNodeValueAsBinaryStream (n
IN DBMS_XMLDOM.domnode,
value IN SYS.utl_BinaryOutputStream);

The application passes an implementation of SYS.utl_BinaryOutputStream into
which Oracle XML DB writes the contents of the node. The data type of the node must
be RAW or CLOB or else an exception is raised.
PROCEDURE getNodeValueAsCharacterStream (n
IN DBMS_XMLDOM.domnode,
value IN SYS.utl_CharacterOutputStream);

The node data is converted, as necessary, to the session character set and then
"pushed" into the SYS.utl_CharacterOutputStream.
The following example fragments illustrate reading the node value as binary data and
driving the write methods in a user-defined subtype of SYS.utl_
BinaryOutPutStream, which is called MyBinaryOutputStream:

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PL/SQL DOM API for XMLType (DBMS_XMLDOM)

Example 13–3

Creating a User-Defined Subtype of SYS.util_BinaryOutputStream()

CREATE TYPE MyBinaryOutputStream UNDER SYS.utl_BinaryOutputStream (
CONSTRUCTOR FUNCTION MyBinaryOutputStream ()
RETURN SELF AS RESULT,
MEMBER FUNCTION write (bytes IN RAW) RETURN INTEGER,
MEMBER PROCEDURE write (bytes IN RAW, offset IN INTEGER, length IN OUT
INTEGER),
MEMBER FUNCTION flush () RETURN BOOLEAN,
MEMBER FUNCTION close () RETURN BOOLEAN);
);
-- Put code here that implements these methods
...
Example 13–4

Retrieving Node Value with a User-Defined Stream

DECLARE
ostream
MyBinaryOutputStream = MyBinaryOutputStream ();
node
DBMS_XMLDOM.domnode;
...
BEGIN
...
-- This drives the write methods in MyBinaryOutputStream,
-- flushes the data, and closes the stream after the value has been
-- completely written.
DBMS_XMLDOM.getNodeValueAsBinaryStream (node, ostream);
...
END;

Get-Pull Model
To read the value of a node in this model, Oracle XML DB creates a binary input
stream or character input stream and returns this to the caller. The character set, C2, of
the character input stream is the current session character set. Oracle XML DB
populates the input stream as the caller pulls the node data from the stream so Oracle
XML DB is again the producer of the data. If the stream is a character input stream,
then the node data type may be any supported by Oracle XML DB and node data, if
character, is converted, if necessary, from C1 to C2. If the node data is non-character, it
is converted to character in C2. If a binary input stream, the data type of the node must
be RAW or BLOB.
The functions of the DBMS_XMLDOM package to be used for this case are
getNodeValueAsBinaryStream and getNodeValueAsCharacterStream.
FUNCTION getNodeValueAsBinaryStream(n IN DBMS_XMLDOM.domnode)
RETURN SYS.utl_BinaryInputStream;

This function returns an instance of the new PL/SQL SYS.utl_
BinaryInputStream that can be read using defined methods as described in the
section "Set-Pull Model" on page 13-16. The node data type must be RAW or BLOB or
else an exception is raised.
FUNCTION getNodeValueAsCharacterStream (n IN DBMS_XMLDOM.domnode)
RETURN SYS.utl_CharacterInputStream;

This function returns an instance of the new PL/SQL SYS.utl_
CharacterInputStream that can be read using defined methods. If the node data is

PL/SQL APIs for XMLType 13-15

PL/SQL DOM API for XMLType (DBMS_XMLDOM)

character it is converted to the current session character set. If the node data is not
character data, it is first converted to character data.
Example 13–5 illustrates reading a node value as binary data in 50-byte increments:
Example 13–5

Get-Pull of Binary Data

DECLARE
istream
SYS.utl_BinaryInputStream;
node
DBMS_XMLDOM.domnode;
buffer
raw(50);
numBytes
pls_integer;
...
BEGIN
...
istream := DBMS_XMLDOM.getNodeValueAsBinaryStream (node);
-- Read stream in 50-byte chunks
LOOP
numBytes := 50;
istream.read ( buffer, numBytes);
if numBytes <= 0 then
exit;
end if;
-- Process next 50 bytes of node value in buffer
END LOOP
...
END;

Example 13–6 illustrates reading a node value as character data in 50-character
increments:
Example 13–6

Get-Pull of Character Data

DECLARE
istream
SYS.utl_CharacterInputStream;
node
DBMS_XMLDOM.domnode;
buffer
varchar2(50);
numChars
pls_integer;
...
BEGIN
...
istream := DBMS_XMLDOM.getNodeValueAsCharacterStream (node);
-- Read stream in 50-character chunks
LOOP
numChars := 50;
istream.read ( buffer, numChars);
IF numChars <= 0 then
exit;
END IF;
-- Process next 50 characters of node value in buffer
END LOOP
...
END;

Set-Pull Model
To write a node value in this mode, the application creates a binary input stream or
character input stream and passes this to Oracle XML DB. The character set of the
character input stream, C2, is the session character set. Oracle XML DB pulls the data
from the input stream and populates the node. If the stream is a character input

13-16 Oracle XML DB Developer's Guide

PL/SQL DOM API for XMLType (DBMS_XMLDOM)

stream, then the data type of the node may be any supported by Oracle XML DB. If the
data type of the node is not character, the stream data is first converted to the node
data type. If the node data type is character, then no conversion occurs, so the node
data remains in character set C2. If the stream is a binary input stream, then the
data type of the node must be RAW or BLOB and no conversion occurs.
The procedures of the DBMS_XMLDOM package to be used for this case are
setNodeValueAsBinaryStream and setNodeValueAsCharacterStream.
PROCEDURE setNodeValueAsBinaryStream(n IN DBMS_XMLDOM.domnode,
value IN SYS.utl_BinaryInputStream);

The application passes in an implementation of SYS.utl_BinaryInputStream
from which Oracle XML DB reads data to populate the node. The data type of the
node must be RAW or BLOB or else an exception is raised.
PROCEDURE setNodeValueAsCharacterStream (n IN DBMS_XMLDOM.domnode,
value IN SYS.utl_CharacterInputStream);

The application passes in an implementation of SYS.utl_CharacterInputStream
from which Oracle XML DB reads to populate the node. The data type of the node
may be any valid type supported by Oracle XML DB. If it is a non-character data type,
the character data read from the stream is converted to the data type of the node. If the
data type of the node is either character or CLOB, then no conversion occurs and the
character set of the node becomes the character set of the PL/SQL session.
Example 13–7 illustrates setting the node value to binary data produced by the read
methods defined in a user-defined subtype of SYS.utl_BinaryInputStream,
which is called MyBinaryInputStream:
Example 13–7

Set-Pull of Binary Data

CREATE TYPE MyBinaryInputStream UNDER SYS.utl_BinaryInputStream (
CONSTRUCTOR FUNCTION MyBinaryInputStream ()
RETURN SELF AS RESULT,
MEMBER FUNCTION read () RETURN RAW,
MEMBER PROCEDURE read (bytes IN OUT RAW, numbytes IN OUT INTEGER),
MEMBER PROCEDURE read (bytes IN OUT RAW,
offset IN INTEGER,
length IN OUT INTEGER),
MEMBER FUNCTION close () RETURN BOOLEAN);

You can use an object of type MyBinaryInputStream to set the value of a node as
follows:
DECLARE
istream
MyBinaryInputStream = MyBinaryInputStream ();
node
DBMS_XMLDOM.domnode;
...
BEGIN
...
-- This drives the read methods in MyBinaryInputStream
DBMS_XMLDOM.setNodeValueAsBinaryStream (node, istream);
...
END;

Set-Push Model
To write a new node value in this mode, Oracle XML DB creates a binary output
stream or character output stream and returns this to the caller. The character set of the

PL/SQL APIs for XMLType 13-17

PL/SQL DOM API for XMLType (DBMS_XMLDOM)

character output stream, C2, is the current session character set. The caller pushes data
into the output stream and Oracle XML DB then writes this to the Oracle XML DB
Node. If the stream is a character output stream, then the data type of the node may be
any type supported by Oracle XML DB. In this case, the character data is converted to
the node data type. If the node data type is character, then the character set, C1, is
changed to C2. No data conversion occurs. If the stream is a binary input stream, and
the data type of the node must be RAW or BLOB. In this case, the stream is read without
data conversion.
The procedures of the DBMS_XMLDOM package to be used for this case are
setNodeValueAsBinaryStream and setNodeValueAsCharacterStream.
FUNCTION setNodeValueAsBinaryStream(n IN DBMS_XMLDOM.domnode)
RETURN SYS.utl_BinaryOutputStream;

This function returns an instance of SYS.utl_BinaryOutputStream into which the
caller can write the node value. The data type of the node must be RAW or BLOB or else
an exception is raised.
FUNCTION setNodeValueAsCharacterStream (n IN DBMS_XMLDOM.domnode)
RETURN SYS.utl_CharacterOutputStream;

This function returns an instance of the PL/SQL SYS.utl_
CharacterOutputStream type into which the caller can write the node value. The
data type of the node can be any valid Oracle XML DB data type. If the type is not
character or CLOB, the character data written to the stream is converted to the node
data type. If the data type of the node is character or CLOB, then the character data
written to the stream is converted from PL/SQL session character set to the character
set of the node
Example 13–8 illustrates setting the value of a node to binary data by writing 50-byte
segments into the SYS.utl_BinaryOutputStream:
Example 13–8

Set-Push of Binary Data

DECLARE
ostream
SYS.utl_BinaryOutputStream;
node
DBMS_XMLDOM.domnode;
buffer
raw(500);
segment
raw(50);
numBytes
pls_integer;
offset
pls_integer;
...
BEGIN
...
ostream := DBMS_XMLDOM.setNodeValueAsBinaryStream (node);
offset := 0;
length := 500;
-- Write to stream in 50-byte chunks
LOOP
numBytes := 50;
-- Get next 50 bytes of buffer
ostream.write ( segment, offset, numBytes);
length := length - numBytes;
IF length <= 0 then
exit;
END IF;
END LOOP
ostream.close();
...

13-18 Oracle XML DB Developer's Guide

PL/SQL Parser API for XMLType (DBMS_XMLPARSER)

END;

Determining Binary Stream or Character Stream
To determine whether to use a character stream or a binary stream to access the node
value use the following method which is also included as part of the DBMS_XMLDOM
package:
FUNCTION useBinaryStream (n IN DBMS_XMLDOM.domnode) RETURN BOOLEAN;

This function returns TRUE if the data type of the node is RAW or BLOB, so that the
node value may be read or written using either a SYS.utl_BinaryInputStream or
a SYS.utl_BinaryOutputStream. If a value of FALSE is returned, the node value
can be accessed only using a SYS.utl_CharacterInputStream or a SYS.utl_
CharacterOutputStream.

PL/SQL Parser API for XMLType (DBMS_XMLPARSER)
XML documents are made up of storage units, called entities, that contain either parsed
or unparsed data. Parsed data is made up of characters, some of which form character
data and some of which form markup. Markup encodes a description of the document
storage layout and logical structure. XML provides a mechanism for imposing
constraints on the storage layout and logical structure.
A software module called an XML parser or processor reads XML documents and
provides access to their content and structure. An XML parser usually does its work
on behalf of another module, typically the application.

Features of the PL/SQL Parser API for XMLType
The PL/SQL Parser API for XMLType (DBMS_XMLPARSER) builds a result tree that can
be accessed by PL/SQL APIs. If parsing fails, it raises an error.
Method DBMS_XMLPARSER.setErrorLog() is not supported.
See Also: Oracle Database PL/SQL Packages and Types Reference for
descriptions of individual DBMS_XMLPARSER methods

Using the PL/SQL Parser API for XMLType (DBMS_XMLPARSER)
Figure 13–2 illustrates how to use the PL/SQL Parser for XMLType (DBMS_
XMLPARSER). These are the steps:
1.

Construct a parser instance using PL/SQL method newParser().

2.

Parse XML documents using PL/SQL methods such as parseBuffer(),
parseClob(), and parse(URI). An error is raised if the input is not a valid
XML document.

3.

Call PL/SQL function getDocument on the parser to obtain a DOMDocument
interface.

PL/SQL APIs for XMLType 13-19

PL/SQL XSLT Processor for XMLType (DBMS_XSLPROCESSOR)

Figure 13–2 Using the PL/SQL Parser API for XMLType
newParser

Parser

parseBuffer

parse (URI)

...

getDocument

DOMDocument

Example 13–9 parses a simple XML document. It creates an XML parser (instance of
DBMS_XMLPARSER.parser) and uses it to parse the XML document (text) in variable
indoc. Parsing creates a DOM document, which is retrieved from the parser using
DBMS_XMLPARSER.getDocument. A DOM node is created that contains the entire
document, and the node is printed. After freeing (destroying) the DOM document, the
parser instance is freed using DBMS_XMLPARSER.freeParser.
Example 13–9

Parsing an XML Document

DECLARE
indoc
VARCHAR2(2000);
indomdoc DBMS_XMLDOM.DOMDocument;
innode
DBMS_XMLDOM.DOMNode;
myparser DBMS_XMLPARSER.parser;
buf
VARCHAR2(2000);
BEGIN
indoc := 'De Selby';
myParser := DBMS_XMLPARSER.newParser;
DBMS_XMLPARSER.parseBuffer(myParser, indoc);
indomdoc := DBMS_XMLPARSER.getDocument(myParser);
innode := DBMS_XMLDOM.makeNode(indomdoc);
DBMS_XMLDOM.writeToBuffer(innode, buf);
DBMS_OUTPUT.put_line(buf);
DBMS_XMLDOM.freeDocument(indomdoc);
DBMS_XMLPARSER.freeParser(myParser);
END;
/

This produces the following output:
De Selby

PL/SQL XSLT Processor for XMLType (DBMS_XSLPROCESSOR)
The W3C XSL Recommendation describes rules for transforming a source tree into a
result tree. A transformation expressed in Extensible Stylesheet Language
Transformation (XSLT) language is called an XSL style sheet. The transformation
specified is achieved by associating patterns with templates defined in the XSLT style
sheet. A template is instantiated to create part of the result tree.

13-20 Oracle XML DB Developer's Guide

PL/SQL XSLT Processor for XMLType (DBMS_XSLPROCESSOR)

Enabling Transformations and Conversions with XSLT
The Oracle XML DB PL/SQL DOM API for XMLType also supports XSLT. This enables
transformation from one XML document to another, or conversion into HTML, PDF, or
other formats. XSLT is also widely used to convert XML to HTML for browser display.
The embedded XSLT processor follows Extensible Stylesheet Language (XSL)
statements and traverses the DOM tree structure for XML data residing in XMLType.
Oracle XML DB applications do not require a separate parser as did the prior release
XML Parser for PL/SQL. However, applications requiring external processing can still
use the XML Parser for PL/SQL first to expose the document structure.
The XML Parser for PL/SQL in Oracle XML Developer's Kit
parses an XML document (or a standalone DTD) so that the XML
document can be processed by an application, typically running on
the client. PL/SQL APIs for XMLType are used for applications that
run on the server and are natively integrated in the database.
Benefits include performance improvements and enhanced access
and manipulation options.

Note:

See Also: Chapter 11, "Transforming and Validating XMLType
Data"

PL/SQL XSLT Processor for XMLType: Features
PL/SQL XSLT Processor for XMLType (DBMS_XSLPROCESSOR) is the Oracle XML DB
implementation of the XSL processor. This follows the W3C XSLT final
recommendation (REC-xslt-19991116). It includes the required action of an XSL
processor in terms of how it must read XSLT style sheets and the transformations it
must achieve. It provides a convenient and efficient way of applying a single style
sheet to multiple documents.
The types and methods of the PL/SQL XSLT Processor API are made available by
PL/SQL package DBMS_XSLPROCESSOR. The methods in this package use PL/SQL
data types PROCESSOR and STYLESHEET, which are specific to the XSL Processor
implementation.
All DBMS_XSLPROCESSOR methods are supported by Oracle XML DB, with the
exception of method setErrorLog().
See Also: Oracle Database PL/SQL Packages and Types Reference for
descriptions of the individual DBMS_XSLPROCESSOR methods

Using the PL/SQL XSLT Processor API for XMLType (DBMS_XSLPROCESSOR)
Figure 13–3 illustrates how to use XSLT Processor for XMLType (DBMS_
XSLPROCESSOR). These are the steps:
1.

Construct an XSLT processor using newProcessor.

2.

Use newStylesheet to build a STYLESHEET object from a DOM document.

3.

Optionally, you can set parameters for the STYLESHEET object using setParams.

4.

Use processXSL to transform a DOM document using the processor and
STYLESHEET object.

5.

Use the PL/SQL DOM API for XMLType to manipulate the result of XSLT
processing.
PL/SQL APIs for XMLType 13-21

PL/SQL XSLT Processor for XMLType (DBMS_XSLPROCESSOR)

Figure 13–3 Using the PL/SQL XSLT Processor for XMLType
XSL Document
(DOMDocument)
newProcessor

newStylesheet

Processor

Stylesheet

xmldoc
(DOMDocument)

setParams

ProcessXSL

DOMDocumentFragment Interface

makeNode

DOMNode Interface

Example 13–10 transforms an XML document using procedure processXSL. It uses
the same parser instance to create two different DOM documents: the XML text to
transform and the XSLT style sheet. An XSL processor instance is created, which
applies the style sheet to the source XML to produce a new DOM fragment. A DOM
node (outnode) is created from this fragment, and the node content is printed. The
output DOM fragment, parser, and XSLT processor instances are freed using
procedures freeDocFrag, freeParser, and freeProcessor, respectively.
Example 13–10 Transforming an XML Document using an XSL Style Sheet
DECLARE
indoc
VARCHAR2(2000);
xsldoc
VARCHAR2(2000);
myParser
DBMS_XMLPARSER.parser;
indomdoc
DBMS_XMLDOM.DOMDocument;
xsltdomdoc DBMS_XMLDOM.DOMDocument;
xsl
DBMS_XSLPROCESSOR.stylesheet;
outdomdocf DBMS_XMLDOM.DOMDocumentFragment;
outnode
DBMS_XMLDOM.DOMNode;
proc
DBMS_XSLPROCESSOR.processor;
buf
VARCHAR2(2000);
BEGIN
indoc := '1
robert
smith
1000
engineer
';
xsldoc := '





13-22 Oracle XML DB Developer's Guide

PL/SQL Translation API for XMLType (DBMS_XMLTRANSLATIONS)










';
myParser := DBMS_XMLPARSER.newParser;
DBMS_XMLPARSER.parseBuffer(myParser, indoc);
indomdoc
:= DBMS_XMLPARSER.getDocument(myParser);
DBMS_XMLPARSER.parseBuffer(myParser, xsldoc);
xsltdomdoc := DBMS_XMLPARSER.getDocument(myParser);
xsl
:= DBMS_XSLPROCESSOR.newStyleSheet(xsltdomdoc, '');
proc
:= DBMS_XSLPROCESSOR.newProcessor;
--apply stylesheet to DOM document
outdomdocf := DBMS_XSLPROCESSOR.processXSL(proc, xsl, indomdoc);
outnode
:= DBMS_XMLDOM.makeNode(outdomdocf);
-- PL/SQL DOM API for XMLType can be used here
DBMS_XMLDOM.writeToBuffer(outnode, buf);
DBMS_OUTPUT.put_line(buf);
DBMS_XMLDOM.freeDocument(indomdoc);
DBMS_XMLDOM.freeDocument(xsltdomdoc);
DBMS_XMLDOM.freeDocFrag(outdomdocf);
DBMS_XMLPARSER.freeParser(myParser);
DBMS_XSLPROCESSOR.freeProcessor(proc);
END;
/

This produces the following output:

1
robert
engineer
smith
1000


PL/SQL Translation API for XMLType (DBMS_XMLTRANSLATIONS)
When you store security objects in the Oracle XML DB Repository, you store them as
XMLType instances. The security objects also contain some strings that must be
translated, so that you can search for or display them in various languages. The
translations for these strings are also stored in the Oracle XML DB Repository, along
with the original strings, because they must be associated with the original document.
You can retrieve and operate on these strings, depending on your language settings.
Oracle XML DB provides translation support through the DBMS_XMLTRANSLATIONS
package, which provides an interface to perform translations so that strings can be
searched or displayed in various languages.
See Also: Chapter 7, "XML Schema Storage and Query: Basic" for an
overview of XML translations

PL/SQL APIs for XMLType 13-23

PL/SQL Translation API for XMLType (DBMS_XMLTRANSLATIONS)

DBMS_XMLTRANSLATIONS Methods
PL/SQL package DBMS_XMLTRANSLATIONS provides the following methods:
■

■

updateTranslation(): Updates the translation in a particular language at the
specified XPATH. If the translation in that language is not present, then it is
inserted.
setSourceLang(): Sets the source language to a particular language at the
specified XPATH.

■

translateXML(): Returns the document in the specified language.

■

getBaseDocument(): Returns the base document with all the translations.

■

■

■

■

extractXLiff(): Extracts the translations in XLIFF format from either an
XMLTYPE instance or a resource in Oracle XML DB Repository.
mergeXLiff(): Merges the translations in XLIFF format into either an XMLTYPE
or a resource in Oracle XML DB Repository.
disableTranslation(): Disables translations in the current session so that
query or retrieval takes place on the base document, ignoring session language
values.
enableTranslation(): Enables translations in the current session.
See Also: Oracle Database PL/SQL Packages and Type References for a
description of the individual DBMS_XMLTRANSLATIONS methods.

13-24 Oracle XML DB Developer's Guide

14
PL/SQL Package DBMS_XMLSTORE
This chapter introduces you to the PL/SQL package DBMS_XMLSTORE. This package is
used to insert, update, and delete data from XML documents in object-relational
tables.
This chapter contains these topics:
■

Overview of PL/SQL Package DBMS_XMLSTORE

■

Using Package DBMS_XMLSTORE

■

Inserting with DBMS_XMLSTORE

■

Updating with DBMS_XMLSTORE

■

Deleting with DBMS_XMLSTORE

Overview of PL/SQL Package DBMS_XMLSTORE
PL/SQL package DBMS_XMLSTORE enables DML operations to be performed on
relational tables using XML. It takes a canonical XML mapping similar to that
produced by package DBMS_XMLGEN; converts it to object-relational constructs; and
then inserts, updates or deletes the corresponding value from relational tables.
The functionality of package DBMS_XMLSTORE is similar to that of package DBMS_
XMLSAVE, which is part of the Oracle XML SQL Utility (XSU). There are, however,
some important differences:
■

■

■

DBMS_XMLSTORE is written in C and compiled into the kernel, so it provides
higher performance.
DBMS_XMLSTORE uses the Simple API for XML (SAX) to parse the input XML
document, so it has higher scalability and lower memory requirements. DBMS_
XMLSTORE lets you input XMLType data, in addition to CLOB and VARCHAR.
PL/SQL functions insertXML, updateXML, and deleteXML, which are also
present in package DBMS_XMLSAVE, have been enhanced in package DBMS_
XMLSTORE to take XMLType instances in addition to CLOB values and strings. This
provides for better integration with Oracle XML DB functionality.

Using Package DBMS_XMLSTORE
To use PL/SQL package DBMS_XMLSTORE, follow these steps:
1.

Create a context handle by calling function DBMS_XMLSTORE.newContext and
supplying it with the table name to use for the DML operations. For case
sensitivity, double-quote (") the string that is passed to the function.

PL/SQL Package DBMS_XMLSTORE 14-1

Inserting with DBMS_XMLSTORE

By default, XML documents are expected to use the  tag to identify rows.
This is the same default used by package DBMS_XMLGEN when generating XML
data. You can use function setRowTag to override this behavior.
2.

For inserts, to improve performance you can specify the list of columns to insert by
calling procedure DBMS_XMLSTORE.setUpdateColumn for each column. The
default behavior (if you do not specify the list of columns) is to insert values for
each column whose corresponding element is present in the XML document.

3.

For updates, use function DBMS_XMLSTORE.setKeyColumn to specify one or
more (pseudo-) key columns, which are used to specify the rows to update. You do
this in the WHERE clause of a SQL UPDATE statement. The columns that you specify
need not be keys of the table, but together they must uniquely specify the rows to
update.
For example, in table employees, column employee_id uniquely identifies rows
(it is a key of the table). If the XML document that you use to update the table
contains element 2176, then the rows where
employee_id equals 2176 are updated.
To improve performance, you can also specify the list of update columns using
DBMS_XMLSTORE.setUpdateColumn. The default behavior is to update all of the
columns in the row(s) identified by setKeyColumn whose corresponding
elements are present in the XML document.

4.

For deletions you specify (pseudo-) key columns to identify the row(s) to delete.
You do this the same way you specify rows to update—see step 3.

5.

Provide a document to PL/SQL function insertXML, updateXML, or
deleteXML. You can repeat this step to update several XML documents.

6.

Close the context by calling function DBMS_XMLSTORE.closeContext.

Inserting with DBMS_XMLSTORE
To insert an XML document into a table or view, you supply the table or view name
and the document. DBMS_XMLSTORE parses the document and then creates an INSERT
statement into which it binds all the values. By default, DBMS_XMLSTORE inserts
values into all the columns represented by elements in the XML document.
Example 14–1 uses DBM_XMLSTORE to insert the information for two new employees
into the employees table. The information is provided in the form of XML data.
Example 14–1

Inserting Data with Specified Columns

SELECT employee_id AS EMP_ID, salary, hire_date, job_id, email, last_name
FROM employees WHERE department_id = 30;
EMP_ID
SALARY HIRE_DATE JOB_ID
------ ---------- --------- ---------114
11000 07-DEC-94 PU_MAN
115
3100 18-MAY-95 PU_CLERK
116
2900 24-DEC-97 PU_CLERK
117
2800 24-JUL-97 PU_CLERK
118
2600 15-NOV-98 PU_CLERK
119
2500 10-AUG-99 PU_CLERK
6 rows selected.
DECLARE
insCtx DBMS_XMLSTORE.ctxType;
14-2 Oracle XML DB Developer's Guide

EMAIL
LAST_NAME
---------- ---------DRAPHEAL
Raphaely
AKHOO
Khoo
SBAIDA
Baida
STOBIAS
Tobias
GHIMURO
Himuro
KCOLMENA
Colmenares

Inserting with DBMS_XMLSTORE

rows NUMBER;
xmlDoc CLOB :=
'

920
1800
30
17-DEC-2002
Strauss
JSTRAUSS
ST_CLERK


921
2000
30
31-DEC-2004
Jones
EJONES
ST_CLERK

';
BEGIN
insCtx := DBMS_XMLSTORE.newContext('HR.EMPLOYEES'); -- Get saved context
DBMS_XMLSTORE.clearUpdateColumnList(insCtx); -- Clear the update settings
-- Set the columns to be updated as a
DBMS_XMLSTORE.setUpdateColumn(insCtx,
DBMS_XMLSTORE.setUpdateColumn(insCtx,
DBMS_XMLSTORE.setUpdateColumn(insCtx,
DBMS_XMLSTORE.setUpdateColumn(insCtx,
DBMS_XMLSTORE.setUpdateColumn(insCtx,
DBMS_XMLSTORE.setUpdateColumn(insCtx,
DBMS_XMLSTORE.setUpdateColumn(insCtx,

list of values
'EMPLOYEE_ID');
'SALARY');
'HIRE_DATE');
'DEPARTMENT_ID');
'JOB_ID');
'EMAIL');
'LAST_NAME');

-- Insert the doc.
rows := DBMS_XMLSTORE.insertXML(insCtx, xmlDoc);
DBMS_OUTPUT.put_line(rows || ' rows inserted.');
-- Close the context
DBMS_XMLSTORE.closeContext(insCtx);
END;
/
2 rows inserted.
PL/SQL procedure successfully completed.
SELECT employee_id AS EMP_ID, salary, hire_date, job_id, email, last_name
FROM employees WHERE department_id = 30;
EMP_ID
SALARY HIRE_DATE JOB_ID
------ ---------- --------- ---------114
11000 07-DEC-94 PU_MAN
115
3100 18-MAY-95 PU_CLERK
116
2900 24-DEC-97 PU_CLERK
117
2800 24-JUL-97 PU_CLERK
118
2600 15-NOV-98 PU_CLERK
119
2500 10-AUG-99 PU_CLERK
920
1800 17-DEC-02 ST_CLERK

EMAIL
LAST_NAME
---------- ---------DRAPHEAL
Raphaely
AKHOO
Khoo
SBAIDA
Baida
STOBIAS
Tobias
GHIMURO
Himuro
KCOLMENA
Colmenares
STRAUSS
Strauss

PL/SQL Package DBMS_XMLSTORE 14-3

Updating with DBMS_XMLSTORE

921

2000 31-DEC-04 ST_CLERK

EJONES

Jones

8 rows selected.

Updating with DBMS_XMLSTORE
To update (modify) existing data using package DBMS_XMLSTORE, you must specify
which rows to update. In SQL, you would do that using a WHERE clause in an UPDATE
statement. With DBMS_XMLSTORE, you do it by calling procedure setKeyColumn
once for each of the columns that are used collectively to identify the row.
You can think of this set of columns as acting like a set of key columns: together, they
specify a unique row to be updated. However, the columns that you use (with
setKeyColumn) need not be keys of the table—as long as they uniquely specify a row,
they can be used with calls to setKeyColumn.
Example 14–2 uses DBM_XMLSTORE to update information. Assuming that the first
name for employee number 188 is incorrectly recorded as Kelly, this example corrects
that first name to Pat. Since column employee_id is a primary key for table
employees, a single call to setKeyColumn specifying column employee_id is
sufficient to identify a unique row for updating.
Example 14–2

Updating Data with Key Columns

SELECT employee_id, first_name FROM employees WHERE employee_id = 188;
EMPLOYEE_ID FIRST_NAME
----------- ---------188 Kelly
1 row selected.
DECLARE
updCtx DBMS_XMLSTORE.ctxType;
rows NUMBER;
xmlDoc CLOB :=
'

188
Pat

';
BEGIN
updCtx := DBMS_XMLSTORE.newContext('HR.EMPLOYEES'); -- get the context
DBMS_XMLSTORE.clearUpdateColumnList(updCtx);
-- clear update settings
-- Specify that column employee_id is a "key" to identify the row to update.
DBMS_XMLSTORE.setKeyColumn(updCtx, 'EMPLOYEE_ID');
rows := DBMS_XMLSTORE.updateXML(updCtx, xmlDoc);
-- update the table
DBMS_XMLSTORE.closeContext(updCtx);
-- close the context
END;
/
SELECT employee_id, first_name FROM employees WHERE employee_id = 188;
EMPLOYEE_ID FIRST_NAME
----------- ---------188 Pat
1 row selected.
14-4 Oracle XML DB Developer's Guide

Deleting with DBMS_XMLSTORE

The following UPDATE statement is equivalent to the use of DBM_XMLSTORE in
Example 14–2:
UPDATE hr.employees SET first_name = 'Pat' WHERE employee_id = 188;

Deleting with DBMS_XMLSTORE
Deletions are treated similarly to updates: you specify the key or pseudo-key columns
that identify the rows to delete.
Example 14–3

DBMS_XMLSTORE.DELETEXML Example

SELECT employee_id FROM employees WHERE employee_id = 188;
EMPLOYEE_ID
----------188
1 row selected.
DECLARE
delCtx DBMS_XMLSTORE.ctxType;
rows NUMBER;
xmlDoc CLOB :=
'

188
50

';
BEGIN
delCtx := DBMS_XMLSTORE.newContext('HR.EMPLOYEES');
DBMS_XMLSTORE.setKeyColumn(delCtx, 'EMPLOYEE_ID');
rows := DBMS_XMLSTORE.deleteXML(delCtx, xmlDoc);
DBMS_XMLSTORE.closeContext(delCtx);
END;
/
SELECT employee_id FROM employees WHERE employee_id = 188;
no rows selected.

PL/SQL Package DBMS_XMLSTORE 14-5

Deleting with DBMS_XMLSTORE

14-6 Oracle XML DB Developer's Guide

15
Java DOM API for XMLType
This chapter describes how to use XMLType in Java, including fetching XMLType data
through Java Database Connectivity (JDBC).
This chapter contains these topics:
■

Overview of Java DOM API for XMLType

■

Java DOM API for XMLType

■

Loading a Large XML Document into the Database using JDBC

■

Java DOM API for XMLType Features

■

Java DOM API for XMLType Classes

■

Handling Large Nodes using Java

■

Using the Java DOM API and JDBC with Binary XML

Overview of Java DOM API for XMLType
Oracle XML DB supports the Java Document Object Model (DOM) Application
Program Interface (API) for XMLType. This is a generic API for client and server, for
both XML schema-based and non-schema-based documents. It is implemented using
Java package oracle.xml.parser.v2. DOM is a tree-based object representation of
XML documents in dynamic memory that enables programmatic access to their
elements and attributes. The DOM object and interface are part of a W3C
recommendation. DOM views the parsed document as a tree of objects.
To access XMLType data using JDBC, use the class oracle.xdb.XMLType.
For XML documents that do not conform to any XML schema, use the Java DOM API
for XMLType, because it can handle any valid XML document.
See Also:

Oracle Database XML Java API Reference

Java DOM API for XMLType
Java DOM API for XMLType handles all kinds of valid XML documents, irrespective of
how they are stored in Oracle XML DB. It presents to the application a uniform view of
the XML document, whether it is XML schema-based or non-schema-based and
whatever the underlying storage model. Java DOM API works on both client and
server.
As discussed in Chapter 13, "PL/SQL APIs for XMLType", the Oracle XML DB DOM
APIs are compliant with the W3C DOM Level 1.0 and Level 2.0 Core
Recommendation.
Java DOM API for XMLType 15-1

Java DOM API for XMLType

The Java DOM API for XMLType can be used to construct an XMLType instance from
data encoded in different character sets.
You can use the Java DOM API for XMLType to access XML documents stored in
Oracle XML DB Repository from Java applications. Naming conforms to the Java
binding for DOM as specified by the W3C DOM Recommendation. The repository can
contain both XML schema-based and non-schema-based documents.

Accessing XMLType Data using JDBC
JDBC is a SQL-based way for Java applications to access any data in Oracle Database,
including XML documents in Oracle XML DB. You use Java class
oracle.xdb.XMLType, method createXML() to create XML data.
Use the thick driver with method XMLType.createXML() if
you pass a stream as input. You cannot use the thin driver in this case.

Note:

Using XMLType Data with JDBC
The JDBC 4.0 standard data type for XML data is java.sql.SQLXML. Method
getObject() returns an object of type oracle.xdb.XMLType. Starting with Oracle
Database Release 2 (11.2.0.3), oracle.xdb.XMLType implements interface
java.sql.SQLXML.

How Java Applications Use JDBC to Access XML Documents in Oracle XML DB
JDBC users can query an XMLType table to obtain a JDBC XMLType interface that
supports all SQL/XML functions supported by SQL data type XMLType. The Java
(JDBC) API for XMLType interface can implement the DOM document interface.
Example 15–1 illustrates how to use JDBC to query an XMLType table:
Example 15–1

Querying an XMLType Table using JDBC

import oracle.xdb.XMLType;
...
OraclePreparedStatement stmt = (OraclePreparedStatement)
conn.prepareStatement("SELECT e.poDoc FROM po_xml_tab e");
ResultSet rset = stmt.executeQuery();
OracleResultSet orset = (OracleResultSet) rset;
while(orset.next())
{
// get the XMLType
XMLType poxml = (XMLType)orset.getObject(1);
// get the XMLDocument as a string...
Document podoc = (Document)poxml.getDOM();
}

You can select XMLType data using JDBC in any of these ways:
■

■

Use SQL/XML function XMLSerialize in SQL, and obtain the result as an
oracle.sql.CLOB, java.lang.String or oracle.sql.BLOB in Java. The
Java snippet in Example 15–2 illustrates this.
Call method getObject() in the PreparedStatement to obtain the whole
XMLType instance. The return value of this method is of type
oracle.xdb.XMLType. Then you can use Java functions on class XMLType to
access the data. Example 15–3 shows how to do this.

15-2 Oracle XML DB Developer's Guide

Java DOM API for XMLType

Example 15–2

Selecting XMLType Data using getStringVal() and getCLOB()

DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
Connection conn =
DriverManager.getConnection("jdbc:oracle:oci8:@", "QUINE", "CURRY");
OraclePreparedStatement stmt =
(OraclePreparedStatement) conn.prepareStatement(
"SELECT XMLSerialize(DOCUMENT e.poDoc AS CLOB) poDoc, " +
"XMLSerialize(DOCUMENT e.poDoc AS VARCHAR2(2000)) poString " +
" FROM po_xml_tab e");
ResultSet rset = stmt.executeQuery();
OracleResultSet orset = (OracleResultSet) rset;
while(orset.next())
{
// the first argument is a CLOB
oracle.sql.CLOB clb = orset.getCLOB(1);
// the second argument is a string..
String poString = orset.getString(2);
// now use the CLOB inside the program
}

Example 15–3 shows the use of method getObject() to directly obtain an XMLType
instance from ResultSet.
Example 15–3

Returning XMLType Data using getObject()

import oracle.xdb.XMLType;
...
PreparedStatement stmt = conn.prepareStatement(
"SELECT e.poDoc FROM po_xml_tab e");
ResultSet rset = stmt.executeQuery();
while(rset.next())
{
// get the XMLType
XMLType poxml = (XMLType)rset.getObject(1);
// get the XML as a string...
String poString = poxml.getStringVal();
}

Example 15–4 shows how to bind an output parameter of type XMLType to a SQL
statement. The output parameter is registered as having data type XMLType.
Example 15–4

Returning XMLType Data using an Output Parameter

public void doCall (String[] args)
throws Exception
{
// CREATE OR REPLACE FUNCTION getPurchaseOrder(reference VARCHAR2)
// RETURN XMLTYPE
// AS
//
xml XMLTYPE;
// BEGIN
//
SELECT OBJECT_VALUE INTO xml
//
FROM purchaseorder
//
WHERE XMLCast(XMLQuery('$p/PurchaseOrder/Reference'
//
PASSING OBJECT_VALUE AS "p" RETURNING CONTENT)
//
AS VARCHAR2(30))
//
= reference;
//
RETURN xml;
// END;
String SQLTEXT = "{? = call getPurchaseOrder('BLAKE-2002100912333601PDT')}";

Java DOM API for XMLType 15-3

Java DOM API for XMLType

CallableStatement sqlStatement = null;
XMLType xml = null;
super.doSomething(args);
createConnection();
try
{
System.out.println("SQL := " + SQLTEXT);
sqlStatement = getConnection().prepareCall(SQLTEXT);
sqlStatement.registerOutParameter (1, OracleTypes.OPAQUE,"SYS.XMLTYPE");
sqlStatement.execute();
xml = (XMLType) sqlStatement.getObject(1);
System.out.println(xml.getStringVal());
}
catch (SQLException SQLe)
{
if (sqlStatement != null)
{
sqlStatement.close();
throw SQLe;
}
}

Manipulating XML Database Documents using JDBC
You can also update, insert, and delete XMLType data using Java Database
Connectivity (JDBC).
XMLType methods extract(), transform(), and
existsNode() work only with the OCI driver.

Note:

Not all oracle.xdb.XMLType functions are supported by the thin
JDBC driver. If you do not use oracle.xdb.XMLType classes and
the OCI driver, you could lose performance benefits associated with
the intelligent handling of XML.
You can update, insert, or delete XMLType data in either of these ways:
■

■

Bind a CLOB instance or a string to an INSERT, UPDATE, or DELETE statement, and
use the XMLType constructor inside SQL to construct the XML instance.
Example 15–5 illustrates this.
Use setObject() in the PreparedStatement to set the entire XMLType
instance. Example 15–6 illustrates this.

Example 15–5

Updating XMLType Data using SQL UPDATE with Constructor XMLType

OraclePreparedStatement stmt =
(OraclePreparedStatement) conn.prepareStatement(
"UPDATE po_xml_tab SET poDoc = XMLType(?)");
// the second argument is a string..
String poString = "200PO_2";
// now bind the string..
stmt.setString(1,poString);
stmt.execute();

15-4 Oracle XML DB Developer's Guide

Java DOM API for XMLType

Example 15–6

Updating XMLType Data using SQL UPDATE with setObject()

import oracle.xdb.XMLType;
...
OraclePreparedStatement stmt =
(OraclePreparedStatement) conn.prepareStatement(
"UPDATE po_xml_tab SET poDoc = ?");
// the second argument is a string
String poString = "200PO_2";
XMLType poXML = XMLType.createXML(conn, poString);
// now bind the string..
stmt.setObject(1,poXML);
stmt.execute();

When selecting XMLType values, JDBC describes the column as an opaque type. You
can select the column type name and compare it with XMLTYPE to see whether you are
dealing with an XMLType instance. Example 15–7 illustrates this.
Example 15–7

Retrieving Metadata about XMLType Data using JDBC

import oracle.sql.*;
import oracle.jdbc.*;
...
OraclePreparedStatement stmt =
(OraclePreparedStatement) conn.prepareStatement(
"SELECT poDoc FROM po_xml_tab");
OracleResultSet rset = (OracleResultSet)stmt.executeQuery();
// Get the resultset metadata
OracleResultSetMetaData mdata =
(OracleResultSetMetaData)rset.getMetaData();
// Describe the column = the column type comes out as OPAQUE
// and column type name comes out as XMLTYPE
if (mdata.getColumnType(1) == OracleTypes.OPAQUE &&
mdata.getColumnTypeName(1).compareTo("SYS.XMLTYPE") == 0)
{
// It is an XMLtype
}

Example 15–8 updates element discount inside element PurchaseOrder stored in
an XMLType column. It uses JDBC and class oracle.xdb.XMLType. It uses the XML
parser to update a DOM tree and write the updated XML value to the XMLType
column.
Example 15–8

Updating an Element in an XMLType Column using JDBC

-- Create po_xml_hist table to store old PurchaseOrders
CREATE TABLE po_xml_hist (xpo XMLType);
/* NOTE: You must have xmlparserv2.jar and xdb.jar in CLASSPATH */
import java.sql.*;
import java.io.*;
import oracle.xml.parser.v2.*;
import org.xml.sax.*;
import org.w3c.dom.*;
import oracle.jdbc.driver.*;
import oracle.sql.*;
import oracle.xdb.XMLType;
Java DOM API for XMLType 15-5

Java DOM API for XMLType

public class tkxmtpje
{
static String conStr = "jdbc:oracle:oci8:@";
static String user = "QUINE";
static String pass = "CURRY";
static String qryStr =
"SELECT x.poDoc from po_xml_tab x " +
"WHERE XMLCast(XMLQuery('/PO/PONO/text()'" +
" PASSING x.poDoc RETURNING CONTENT)" +
" AS NUMBER)" +
" = 200";
static String updateXML(String xmlTypeStr)
Java DOM API for XMLType
Beta Draft Java DOM API for XMLType 15-7
{
System.out.println("\n===============================");
System.out.println("xmlType.getStringVal():");
System.out.println(xmlTypeStr);
System.out.println("===============================");
String outXML = null;
try {
DOMParser parser = new DOMParser();
parser.setValidationMode(false);
parser.setPreserveWhitespace (true);
parser.parse(new StringReader(xmlTypeStr));
System.out.println("xmlType.getStringVal(): xml String is well-formed");
XMLDocument doc = parser.getDocument();
NodeList nl = doc.getElementsByTagName("DISCOUNT");
for(int i=0;i

200

2
John Nike

323 College Drive
Edison
NJ
08820



Java DOM API for XMLType 15-7

Java DOM API for XMLType

609-555-1212
201-555-1212


20-APR-97
20-MAY-97 12.00.00.000000 AM



6750
2

1
10



4500.23
2

2
10



55 Madison Ave
Madison
WI
53715



Example 15–10 does all of the following:
■

Selects an XMLType instance from an XMLType table

■

Extracts portions of the XMLType instance, based on an XPath expression

■

Checks for the existence of elements

■

Transforms the XMLType instance to another XML format based on XSL

■

Checks the validity of the XMLType document against an XML schema

Example 15–10 Manipulating an XMLType Column using JDBC
import
import
import
import
import
import
import
import
import
import
import
import
import
import
import
public

java.sql.*;
java.io.*;
java.net.*;
java.util.*;
oracle.xml.parser.v2.*;
oracle.xml.parser.schema.*;
org.xml.sax.*;
org.w3c.dom.*;
oracle.xml.sql.dataset.*;
oracle.xml.sql.query.*;
oracle.xml.sql.docgen.*;
oracle.xml.sql.*;
oracle.jdbc.driver.*;
oracle.sql.*;
oracle.xdb.XMLType;
class tkxmtpk1

15-8 Oracle XML DB Developer's Guide

Java DOM API for XMLType

{
static String conStr = "jdbc:oracle:oci8:@";
static String user = "tpjc";
static String pass = "tpjc";
static String qryStr = "select x.resume from t1 x where id<3";
static String xslStr =
" " +
" " +
" " +
" " +
" " +
" " +
" " +
"  " +
" This is Test " +
"  " +
" " +
" " +
"";
static void parseArg(String args[])
{
conStr = (args.length >= 1 ? args[0]:conStr);
user = (args.length >= 2 ? args[1].substring(0, args[1].indexOf("/")):user);
pass = (args.length >= 2 ? args[1].substring(args[1].indexOf("/")+1):pass);
qryStr = (args.length >= 3 ? args[2]:qryStr);
}
/**
* Print the byte array contents
*/
static void showValue(byte[] bytes) throws SQLException
{
if (bytes == null)
System.out.println("null");
else if (bytes.length == 0)
System.out.println("empty");
else
{
for(int i=0; i
#endif
#ifndef ORATYPES_ORACLE
#include 
#endif

Using the C API for XML 16-3

Initializing and Terminating an XML Context

#ifndef XML_ORACLE
#include 
#endif
#ifndef OCIXML_ORACLE
#include 
#endif
#ifndef OCI_ORACLE
#include 
#endif
#include 
typedef struct test_ctx {
OCIEnv *envhp;
OCIError *errhp;
OCISvcCtx *svchp;
OCIStmt *stmthp;
OCIServer *srvhp;
OCIDuration dur;
OCISession *sesshp;
oratext *username;
oratext *password;
} test_ctx;
/* Helper function 1: execute a sql statement which binds xml data */
STATICF sword exec_bind_xml(OCISvcCtx *svchp,
OCIError *errhp,
OCIStmt *stmthp,
void *xml,
OCIType *xmltdo,
OraText *sqlstmt);
/* Helper function 2: Initialize OCI handles and connect */
STATICF sword init_oci_handles(test_ctx *ctx);
/* Helper function 3: Free OCI handles and disconnect */
STATICF sword free_oci_handles(test_ctx *ctx);
void main()
{
test_ctx temp_ctx;
test_ctx *ctx = &temp_ctx;
OCIType *xmltdo = (OCIType *) 0;
xmldocnode *doc = (xmldocnode *)0;
ocixmldbparam params[1];
xmlnode *quux, *foo, *foo_data, *top;
xmlerr err;
sword status = 0;
xmlctx *xctx;
oratext ins_stmt[] = "insert into my_table values (:1)";
oratext tlpxml_test_sch[] = "";
ctx->username = (oratext *)"capiuser";
ctx->password = (oratext *)"***********"; /* Replace with real password */
/* Initialize envhp, svchp, errhp, dur, stmthp */
init_oci_handles(ctx);
/* Get an xml context */
params[0].name_ocixmldbparam = XCTXINIT_OCIDUR;
params[0].value_ocixmldbparam = &ctx->dur;

16-4 Oracle XML DB Developer's Guide

Initializing and Terminating an XML Context

xctx = OCIXmlDbInitXmlCtx(ctx->envhp, ctx->svchp, ctx->errhp, params, 1);
/* Start processing - first, check that this DOM supports XML 1.0 */
printf("\n\nSupports XML 1.0? : %s\n",
XmlHasFeature(xctx, (oratext *) "xml", (oratext *) "1.0") ?
"YES" : "NO");
/* Parse a document */
if (!(doc = XmlLoadDom(xctx, &err, "buffer", tlpxml_test_sch,
"buffer_length", sizeof(tlpxml_test_sch)-1,
"validate", TRUE, NULL)))
{
printf("Parse failed, code %d\n", err);
}
else
{
/* Get the document element */
top = (xmlnode *)XmlDomGetDocElem(xctx, doc);
/* Print out the top element */
printf("\n\nOriginal top element is :\n");
XmlSaveDom(xctx, &err, top, "stdio", stdout, NULL);
/* Print out the document-note that the changes are reflected here */
printf("\n\nOriginal document is :\n");
XmlSaveDom(xctx, &err, (xmlnode *)doc, "stdio", stdout, NULL);
/* Create some elements and add them to the document */
quux = (xmlnode *) XmlDomCreateElem(xctx ,doc, (oratext *) "QUUX");
foo = (xmlnode *) XmlDomCreateElem(xctx, doc, (oratext *) "FOO");
foo_data = (xmlnode *) XmlDomCreateText(xctx, doc, (oratext *) "data");
foo_data = XmlDomAppendChild(xctx, (xmlnode *) foo, (xmlnode *) foo_data);
foo = XmlDomAppendChild(xctx, quux, foo);
quux = XmlDomAppendChild(xctx, top, quux);
/* Print out the top element */
printf("\n\nNow the top element is :\n");
XmlSaveDom(xctx, &err, top, "stdio", stdout, NULL);
/* Print out the document. Note that the changes are reflected here */
printf("\n\nNow the document is :\n");
XmlSaveDom(xctx, &err, (xmlnode *)doc, "stdio", stdout, NULL);
/* Insert the document into my_table */
status = OCITypeByName(ctx->envhp, ctx->errhp, ctx->svchp,
(const text *) "SYS", (ub4) strlen((char *)"SYS"),
(const text *) "XMLTYPE",
(ub4) strlen((char *)"XMLTYPE"), (CONST text *) 0,
(ub4) 0, OCI_DURATION_SESSION, OCI_TYPEGET_HEADER,
(OCIType **) &xmltdo);
if (status == OCI_SUCCESS)
{
exec_bind_xml(ctx->svchp, ctx->errhp, ctx->stmthp, (void *)doc, xmltdo,
ins_stmt);
}
}
/* Free xml ctx */
OCIXmlDbFreeXmlCtx(xctx);
/* Free envhp, svchp, errhp, stmthp */

Using the C API for XML 16-5

Using the C API for XML with Binary XML

free_oci_handles(ctx);
}

The output from compiling and running this C program is as follows:
Supports XML 1.0? : YES
Original top element is :

Original document is :

Now the top element is :


data


Now the document is :


data



This is the result of querying the constructed document in my_table:
SELECT * FROM my_table;
SYS_NC_ROWINFO$
--------------

data


1 row selected.

Example 16–1 constructs an XML document using the C DOM API and saves it to the
database. The code uses helper functions exec_bind_xml, init_oci_handles, and
free_oci_handles, which are not listed here. The complete listing of this example,
including the helper functions, can be found in Appendix A, "Oracle-Supplied XML
Schemas and Examples", "Initializing and Terminating an XML Context (OCI)" on
page A-47.
Example 16–4 queries table my_table to show the data that was inserted by
Example 16–1.

Using the C API for XML with Binary XML
XML data can be stored in Oracle XML DB using XMLType, and one of the storage
models for this abstract data type is binary XML. Binary XML is a compact, XML
Schema-aware encoding of XML data. You can use it as a storage model for XMLType
in the database, but you can also use it for XML data located outside the database. As
explained in "Using OCI and the C API for XML with Oracle XML DB" on page 16-2,

16-6 Oracle XML DB Developer's Guide

Using the C API for XML with Binary XML

client-side processing of XML data can involve data stored in Oracle XML DB or
transient data that resides outside the database.
You can use the C API for XML to read or write XML data that is encoded as binary
XML from or to Oracle XML DB. Doing so involves the usual read and write
procedures.
Binary XML is XML Schema-aware and can use various encoding schemes, depending
on your needs and your data. Because of this, in order to manipulate binary XML data,
you must have both the data and this metadata about the relevant XML schemas and
encodings.
For XMLType data stored in the database, this metadata is also stored in the database.
However, depending on how your database and data are set up, the metadata might
not be on the same server as the data it applies to. If this is the case, then, before you
can read or write binary XML data from or to the database, you must carry out these
steps:
1.

Create a context instance for the metadata.

2.

Associate this context with a data connection that you use to access binary XML
data in the database. A data connection can be a dedicated connection
(OCISvcCtx) or a connection pool (OCICPool).

Then, when your application needs to encode or decode binary XML data on the data
connection, it automatically fetches the metadata needed for that. The overall sequence
of actions is thus as follows:
1.

Create the usual OCI handles for environment (OCIEnv), connection
(OCISvcCtx), and error context (OCIError).

2.

Create one or more metadata contexts, as needed. A metadata context is
sometimes referred to as a metadata repository, and OCIBinXMLReposCtx is the
OCI context data structure.
You use OCIBinXMLCreateReposCtxFromConn to create a metadata context
from a dedicated connection and OCIBinXMLCreateReposCtxFromCPool to
create a context from a connection pool.

3.

Associate the metadata context(s) with the binary XML data connection(s). You
use OCIBinXmlSetReposCtxForConn to do this.

4.

(Optional) If the XML data originated outside of the database, use
setPicklePreference to specify that XML data to be sent to the database from
now on is in binary XML format. This applies to a DOM document (xmldomdoc).
If you do not specify binary XML, the data is stored as text (CLOB).

5.

Use OCI libraries to read and write XML data from and to the database. Whenever
it is needed for encoding or decoding binary XML documents, the necessary
metadata is fetched automatically using the metadata context.
Use the C DOM API for XML to operate on the XML data at the client level.

Example 16–2 illustrates this.
Example 16–2

Using the C API for XML with Binary XML

. . .
/* Private types and constants */
#define SCHEMA
(OraText *)"SYS"
#define TYPE
(OraText *)"XMLTYPE"
#define USER
(OraText *)"oe"
#define USER_LEN
(ub2)(strlen((char *)USER))

Using the C API for XML 16-7

Using the C API for XML with Binary XML

#define
#define
#define
STATICF
STATICF

PWD
(OraText *)"oe"
PWD_LEN
(ub2)(strlen((char *)PWD))
NUM_PARAMS
1
void checkerr(OCIError *errhp, sword status);
sword create_env(OraText *user, ub2 user_len, OraText *pwd, ub2 pwd_len,
OCIEnv **envhp, OCISvcCtx **svchp, OCIError **errhp);
STATICF sword run_example(OCIEnv *envhp, OCISvcCtx *svchp, OCIError *errhp,
OCIDuration dur);
STATICF void cleanup(OCIEnv *envhp, OCISvcCtx *svchp, OCIError *errhp);
int main (int argc, char *argv[])
{
OCIEnv
*envhp;
OCISvcCtx *svchp;
OCIError
*errhp;
printf("*** Starting Binary XML Example program\n");
if (create_env(USER, USER_LEN, PWD, PWD_LEN, &envhp, &svchp, &errhp))
{
printf("FAILED: create_env()\n");
cleanup(envhp, svchp, errhp);
return OCI_ERROR;
}
if (run_example(envhp, svchp, errhp, OCI_DURATION_SESSION))
{
printf("FAILED: run_example()\n");
cleanup(envhp, svchp, errhp);
return OCI_ERROR;
}
cleanup(envhp, svchp, errhp);
printf ("*** Completed Binary XML example\n");
return OCI_SUCCESS;
}
STATICF sword create_env(OraText *user, ub2 user_len,
OraText *pwd, ub2 pwd_len,
OCIEnv **envhp, OCISvcCtx **svchp, OCIError **errhp)
{
sword
status;
OCIServer *srvhp;
OCISession *usrp;
OCICPool
*poolhp;
OraText
*poolname;
ub4
poolnamelen;
OraText
*database =(OraText *)"";
OCIBinXmlReposCtx *rctx;
/* Create and initialize environment. Allocate error handle. */
. . .
if ((status = OCIConnectionPoolCreate((dvoid *)*envhp, (dvoid*)*errhp,
(dvoid *)poolhp, &poolname,
(sb4 *)&poolnamelen,
(OraText *)0,
(sb4) 0, 1, 10, 1,
(OraText *)USER,
(sb4) USER_LEN,
(OraText *)PWD,
(sb4) PWD_LEN,
OCI_DEFAULT)) != OCI_SUCCESS)
{
printf ("OCIConnectionPoolCreate - Fail %d\n", status);
return OCI_ERROR;

16-8 Oracle XML DB Developer's Guide

Using the Oracle XML Developer's Kit Pull Parser with Oracle XML DB

}
status = OCILogon2((OCIEnv *)*envhp, *errhp, svchp, (OraText *)USER,
(ub4)USER_LEN, (const oratext *)PWD, (ub4)PWD_LEN,
(const oratext *)poolname, poolnamelen, OCI_CPOOL);
if (status)
{
printf ("OCILogon2 - Fail %d\n", status);
return OCI_ERROR;
}
OCIBinXmlCreateReposCtxFromCPool(*envhp, poolhp, *errhp, &rctx);
OCIBinXmlSetReposCtxForConn(*svchp, rctx);
return OCI_SUCCESS;
}
STATICF sword run_example(OCIEnv *envhp, OCISvcCtx *svchp, OCIError *errhp,
OCIDuration dur)
{
OCIType
*xmltdo = (OCIType *)0;
OCIStmt
*stmthp;
OCIDefine *defnp;
xmldocnode *xmldoc = (xmldocnode *)0;
ub4
xmlsize = 0;
text
*selstmt = (text *)"SELECT doc FROM po_binxmltab";
sword
status;
struct xmlctx *xctx = (xmlctx *) 0;
ocixmldbparam params[NUM_PARAMS];
xmlerr xerr = (xmlerr) 0;
/* Obtain type definition for XMLType. Allocate statement handle.
Prepare SELECT statement. Define variable for XMLType. Execute statement. */
. . .
/* Construct xmlctx for using XML C API */
params[0].name_ocixmldbparam = XCTXINIT_OCIDUR;
params[0].value_ocixmldbparam = &dur;
xctx = OCIXmlDbInitXmlCtx(envhp, svchp, errhp, params, NUM_PARAMS);
/* Print result to local string */
XmlSaveDom(xctx, &xerr, (xmlnode *)xmldoc, "stdio", stdout, NULL);
/* Free instances */
. . .
}

See Also:
■

"XMLType Storage Models" on page 1-14

■

Oracle XML Developer's Kit Programmer's Guide

Using the Oracle XML Developer's Kit Pull Parser with Oracle XML DB
You can use the Oracle XML Developer's Kit pull parser with XMLType instances in
Oracle XML DB. When you use this parser, parsing is done on demand, so your
application drives the parsing process. Your application accesses an XML document
through a sequence of events, with start tags, end tags, and comments, just as in
Simple API for XML (SAX) parsing. However, unlike the case of SAX parsing, where
parsing events are handled by callbacks, in pull parsing your application calls
methods to ask for (pull) events only when it needs them. This gives the application
more control over XML processing. In particular, filtering is more flexible with the pull
parser than with the SAX parser.
You can also use the Oracle XML Developer's Kit pull parser to perform stream-based
XML Schema validation.
Using the C API for XML 16-9

Using the Oracle XML Developer's Kit Pull Parser with Oracle XML DB

Example 16–3 shows how to use the Oracle XML DB pull parser with an XMLType
instance. To use the pull parser, you also need static library libxml10.a on UNIX
and Linux systems or oraxml10.dll on Microsoft Windows systems. You also need
header file xmlev.h.
See Also:
■

■

Example 16–3

Oracle XML Developer's Kit Programmer's Guide for information
about the Oracle XML Developer's Kit pull parser
Oracle XML Developer's Kit Programmer's Guide for information on
using the pull parser for stream-based validation

Using the Oracle XML DB Pull Parser

#define MAXBUFLEN 64*1024
void main()
{
test_ctx temp_ctx;
test_ctx *ctx = &temp_ctx;
OCIType *xmltdo = (OCIType *) 0;
ocixmldbparam params[1];
sword status = 0;
xmlctx *xctx;
OCIDefine *defnp = (OCIDefine *) 0;
oratext sel_stmt[] =
"SELECT XMLSerialize(DOCUMENT x.OBJECT_VALUE AS CLOB) FROM PURCHASEORDER x where rownum = 1";
OCILobLocator *cob;
ub4 amtp, nbytes;
ub1 bufp[MAXBUFLEN];
ctx->username = (oratext *)"oe";
ctx->password = (oratext *)"*************";
/* Replace with real password */
/* Initialize envhp, svchp, errhp, dur, stmthp */
init_oci_handles(ctx);
/* Get an xml context */
params[0].name_ocixmldbparam = XCTXINIT_OCIDUR;
params[0].value_ocixmldbparam = &ctx->dur;
xctx = OCIXmlDbInitXmlCtx(ctx->envhp, ctx->svchp, ctx->errhp, params, 1);
/* Start processing */
printf("\n\nSupports XML 1.0? : %s\n",
XmlHasFeature(xctx, (oratext *) "xml", (oratext *) "1.0") ?
"YES" : "NO");
/* Allocate the lob descriptor */
status = OCIDescriptorAlloc((dvoid *) ctx->envhp, (dvoid **) &clob,
(ub4)OCI_DTYPE_LOB, (size_t) 0, (dvoid **) 0);
if (status)
{
printf("OCIDescriptorAlloc Failed\n");
goto error;
}
status = OCIStmtPrepare(ctx->stmthp, ctx->errhp,
(CONST OraText *)sel_stmt, (ub4) strlen((char *)sel_stmt),
(ub4) OCI_NTV_SYNTAX, (ub4) OCI_DEFAULT);
if (status)
{
printf("OCIStmtPrepare Failed\n");
goto error;

16-10 Oracle XML DB Developer's Guide

Using the Oracle XML Developer's Kit Pull Parser with Oracle XML DB

}
status = OCIDefineByPos(ctx->stmthp, &defnp, ctx->errhp, (ub4) 1,
(dvoid *) &clob, (sb4) -1, (ub2 ) SQLT_CLOB,
(dvoid *) 0, (ub2 *)0,
(ub2 *)0, (ub4) OCI_DEFAULT);
if (status)
{
printf("OCIDefineByPos Failed\n");
goto error;
}
status = OCIStmtExecute(ctx->svchp, ctx->stmthp, ctx->errhp, (ub4) 1,
(ub4) 0, (CONST OCISnapshot*) 0, (OCISnapshot*) 0,
(ub4) OCI_DEFAULT);
if (status)
{
printf("OCIStmtExecute Failed\n");
goto error;
}
/* read the fetched value into a buffer */
amtp = nbytes = MAXBUFLEN-1;
status = OCILobRead(ctx->svchp, ctx->errhp, clob, &amtp,
(ub4) 1, (dvoid *) bufp, (ub4) nbytes, (dvoid *)0,
(sb4 (*)(dvoid *, CONST dvoid *, ub4, ub1)) 0,
(ub2) 0, (ub1) SQLCS_IMPLICIT);
if (status)
{
printf("OCILobRead Failed\n");
goto error;
}
bufp[amtp] = '\0';
if (amtp > 0)
{
printf("\n=> Query result of %s: \n%s\n", sel_stmt, bufp);
/********** PULL PARSING ******************/
status = pp_parse(xctx, bufp, amtp);
if (status)
printf("Pull Parsing failed\n");
}
error:
/* Free XML Ctx */
OCIXmlDbFreeXmlCtx(xctx);
/* Free envhp, svchp, errhp, stmthp */
free_oci_handles(ctx);
}
#define ERRBUFLEN 256
sb4 pp_parse(xctx, buf, amt)
xmlctx *xctx;
oratext *buf;
ub4
amt;
{
xmlevctx *evctx;
xmlerr
xerr = XMLERR_OK;
oratext message[ERRBUFLEN];
oratext *emsg = message;
xmlerr
ecode;
boolean done, inattr = FALSE;
xmlevtype event;
/* Create an XML event context - Pull Parser Context */

Using the C API for XML

16-11

Using the Oracle XML Developer's Kit Pull Parser with Oracle XML DB

evctx = XmlEvCreatePPCtx(xctx, &xerr,
"expand_entities", FALSE,
"validate", TRUE,
"attr_events", TRUE,
"raw_buffer_len", 1024,
NULL);
if (!evctx)
{
printf("FAILED: XmlEvCreatePPCtx: %d\n", xerr);
return OCI_ERROR;
}
/* Load the document from input buffer */
xerr = XmlEvLoadPPDoc(xctx, evctx, "buffer", buf, amt, "utf-8");
if (xerr)
{
printf("FAILED: XmlEvLoadPPDoc: %d\n", xerr);
return OCI_ERROR;
}
/* Process the events until END_DOCUMENT event or error */
done = FALSE;
while(!done)
{
event = XmlEvNext(evctx);
switch(event)
{
case XML_EVENT_START_ELEMENT:
printf("START ELEMENT: %s\n", XmlEvGetName0(evctx));
break;
case XML_EVENT_END_ELEMENT:
printf("END ELEMENT: %s\n", XmlEvGetName0(evctx));
break;
case XML_EVENT_START_DOCUMENT:
printf("START DOCUMENT\n");
break;
case XML_EVENT_END_DOCUMENT:
printf("END DOCUMENT\n");
done = TRUE;
break;
case XML_EVENT_START_ATTR:
printf("START ATTRIBUTE: %s\n", XmlEvGetAttrName0(evctx, 0));
inattr = TRUE;
break;
case XML_EVENT_END_ATTR:
printf("END ATTRIBUTE: %s\n", XmlEvGetAttrName0(evctx, 0));
inattr = FALSE;
break;
case XML_EVENT_CHARACTERS:
if (inattr)
printf("ATTR VALUE: %s\n", XmlEvGetText0(evctx));
else
printf("TEXT: %s\n", XmlEvGetText0(evctx));
break;
case XML_EVENT_ERROR:
case XML_EVENT_FATAL_ERROR:
done = TRUE;
ecode = XmlEvGetError(evctx, &emsg);
printf("ERROR: %d: %s\n", ecode, emsg);
break;
}
}

16-12 Oracle XML DB Developer's Guide

Using the Oracle XML Developer's Kit Pull Parser with Oracle XML DB

/* Destroy the event context */
XmlEvDestroyPPCtx(xctx, evctx);
return OCI_SUCCESS;
}

The output from compiling and running this C program is as follows:
=> Query result of XMLSerialize(DOCUMENT x.OBJECT_VALUE AS CLOB) FROM PURCHASEORDER x where rownum = 1:


AMCEWEN-20021009123336171PDT


KPARTNER



Allan D. McEwen
AMCEWEN
S30

Allan D. McEwen
Oracle Plaza
Twin Dolphin Drive
Redwood Shores
CA
94065
USA
650 506 7700

Ground


Salesman


. . .


START DOCUMENT
START ELEMENT: PurchaseOrder
START ATTRIBUTE: xmlns:xsi
ATTR VALUE: http://www.w3.org/2001/XMLSchema-instance
END ATTRIBUTE: xmlns:xsi
START ATTRIBUTE: xsi:noNamespaceSchemaLocation
ATTR VALUE: http://localhost:8080/source/schemas/poSource/xsd/purchaseOrder.xsd
END ATTRIBUTE: xsi:noNamespaceSchemaLocation
START ELEMENT: Reference
TEXT: AMCEWEN-20021009123336171PDT
END ELEMENT: Reference
START ELEMENT: Actions
START ELEMENT: Action
START ELEMENT: User
TEXT: KPARTNER
END ELEMENT: User
END ELEMENT: Action
END ELEMENT: Actions
START ELEMENT: Reject
END ELEMENT: Reject
START ELEMENT: Requestor

Using the C API for XML

16-13

Common XMLType Operations in C

TEXT: Allan D. McEwen
END ELEMENT: Requestor
START ELEMENT: User
TEXT: AMCEWEN
END ELEMENT: User
START ELEMENT: CostCenter
TEXT: S30
END ELEMENT: CostCenter
START ELEMENT: ShippingInstructions
START ELEMENT: name
TEXT: Allan D. McEwen
END ELEMENT: name
START ELEMENT: address
TEXT: Oracle Plaza
Twin Dolphin Drive
Redwood Shores
CA
94065
USA
END ELEMENT: address
START ELEMENT: telephone
TEXT: 650 506 7700
END ELEMENT: telephone
END ELEMENT: ShippingInstructions
START ELEMENT: SpecialInstructions
TEXT: Ground
END ELEMENT: SpecialInstructions
START ELEMENT: LineItems
START ELEMENT: LineItem
START ATTRIBUTE: ItemNumber
ATTR VALUE: 1
END ATTRIBUTE: ItemNumber
START ELEMENT: Description
TEXT: Salesman
END ELEMENT: Description
START ELEMENT: Part
START ATTRIBUTE: Id
ATTR VALUE: 37429158920
END ATTRIBUTE: Id
START ATTRIBUTE: UnitPrice
ATTR VALUE: 39.95
END ATTRIBUTE: UnitPrice
START ATTRIBUTE: Quantity
ATTR VALUE: 2
END ATTRIBUTE: Quantity
END ELEMENT: Part
END ELEMENT: LineItem
. . .
END ELEMENT: LineItems
END ELEMENT: PurchaseOrder
END DOCUMENT

Common XMLType Operations in C
Table 16–2 provides the XMLType functional equivalent of common XML operations.

16-14 Oracle XML DB Developer's Guide

Common XMLType Operations in C

Table 16–2

Common XMLType Operations in C

Description

C API XMLType Function

Create empty XMLType instance

XmlCreateDocument()

Create from a source buffer

XmlLoadDom()

Extract an XPath expression

XmlXPathEvalexpr() and family

Transform using an XSLT style sheet

XmlXslProcess() and family

Check if an XPath exists

XmlXPathEvalexpr() and family

Is document schema-based?

XmlDomIsSchemaBased()

Get schema information

XmlDomGetSchema()

Get document namespace

XmlDomGetNodeURI()

Validate using schema

XmlSchemaValidate()

Obtain DOM from XMLType

Cast (void *) to (xmldocnode *)

Obtain XMLType from DOM

Cast (xmldocnode *) to (void *)

Oracle XML Developer's Kit Programmer's Guide "XML
Parser for C"

See Also:

Example 16–4 shows how to use the DOM to determine how many instances of a
particular part have been ordered. The part in question has Id 37429158722. See
Appendix A, "Oracle-Supplied XML Schemas and Examples", Example A–5 on
page A-47 for the definitions of helper functions exec_bind_xml, free_oci_
handles, and init_oci_handles.
Example 16–4

Using the DOM to Count Ordered Parts

#ifndef S_ORACLE
#include 
#endif
#ifndef ORATYPES_ORACLE
#include 
#endif
#ifndef XML_ORACLE
#include 
#endif
#ifndef OCIXML_ORACLE
#include 
#endif
#ifndef OCI_ORACLE
#include 
#endif
#include 
typedef struct test_ctx {
OCIEnv *envhp;
OCIError *errhp;
OCISvcCtx *svchp;
OCIStmt *stmthp;
OCIServer *srvhp;
OCIDuration dur;
OCISession *sesshp;
oratext *username;
oratext *password;

Using the C API for XML

16-15

Common XMLType Operations in C

} test_ctx;
/* Helper function 1: execute a sql statement which binds xml data */
STATICF sword exec_bind_xml(OCISvcCtx *svchp,
OCIError *errhp,
OCIStmt *stmthp,
void *xml,
OCIType *xmltdo,
OraText *sqlstmt);
/* Helper function 2: Initialize OCI handles and connect */
STATICF sword init_oci_handles(test_ctx *ctx);
/* Helper function 3: Free OCI handles and disconnect */
STATICF sword free_oci_handles(test_ctx *ctx);
void main()
{
test_ctx temp_ctx;
test_ctx *ctx = &temp_ctx;
OCIType *xmltdo = (OCIType *) 0;
xmldocnode *doc = (xmldocnode *)0;
ocixmldbparam params[1];
xmlnode *quux, *foo, *foo_data, *top;
xmlerr err;
sword status = 0;
xmlctx *xctx;
ub4 xmlsize = 0;
OCIDefine *defnp = (OCIDefine *) 0;
oratext sel_stmt[] = "SELECT SYS_NC_ROWINFO$ FROM PURCHASEORDER";
xmlnodelist *litems = (xmlnodelist *)0;
xmlnode *item = (xmlnode *)item;
xmlnode *part;
xmlnamedmap *attrs;
xmlnode *id;
xmlnode *qty;
oratext *idval;
oratext *qtyval;
ub4 total_qty;
int i;
int numdocs;
ctx->username = (oratext *)"oe";
ctx->password = (oratext *)"***********";

/* Replace with real password */

/* Initialize envhp, svchp, errhp, dur, stmthp */
init_oci_handles(ctx);
/* Get an xml context */
params[0].name_ocixmldbparam = XCTXINIT_OCIDUR;
params[0].value_ocixmldbparam = &ctx->dur;
xctx = OCIXmlDbInitXmlCtx(ctx->envhp, ctx->svchp, ctx->errhp, params, 1);
/* Start processing */
printf("\n\nSupports XML 1.0? : %s\n",
XmlHasFeature(xctx, (oratext *) "xml", (oratext *) "1.0") ?
"YES" : "NO");
/* Get the documents from the database using a select statement */
status = OCITypeByName(ctx->envhp, ctx->errhp, ctx->svchp, (const text *) "SYS",

16-16 Oracle XML DB Developer's Guide

Common XMLType Operations in C

status =

status =

status =

status =

(ub4) strlen((char *)"SYS"), (const text *) "XMLTYPE",
(ub4) strlen((char *)"XMLTYPE"), (CONST text *) 0,
(ub4) 0, OCI_DURATION_SESSION, OCI_TYPEGET_HEADER,
(OCIType **) &xmltdo);
OCIStmtPrepare(ctx->stmthp, ctx->errhp,
(CONST OraText *)sel_stmt, (ub4) strlen((char *)sel_stmt),
(ub4) OCI_NTV_SYNTAX, (ub4) OCI_DEFAULT);
OCIDefineByPos(ctx->stmthp, &defnp, ctx->errhp, (ub4) 1, (dvoid *) 0,
(sb4) 0, SQLT_NTY, (dvoid *) 0, (ub2 *)0,
(ub2 *)0, (ub4) OCI_DEFAULT);
OCIDefineObject(defnp, ctx->errhp, (OCIType *) xmltdo,
(dvoid **) &doc,
&xmlsize, (dvoid **) 0, (ub4 *) 0);
OCIStmtExecute(ctx->svchp, ctx->stmthp, ctx->errhp, (ub4) 0, (ub4) 0,
(CONST OCISnapshot*) 0, (OCISnapshot*) 0, (ub4) OCI_DEFAULT);

/* Initialize variables */
total_qty = 0;
numdocs = 0;
/* Loop through all the documents */
while ((status = OCIStmtFetch2(ctx->stmthp, ctx->errhp, (ub4) 1, (ub4) OCI_
FETCH_NEXT,
(ub4)1, (ub4) OCI_DEFAULT)) == 0)
{
numdocs++;
/* Get all the LineItem elements */
litems = XmlDomGetDocElemsByTag(xctx, doc, (oratext *)"LineItem");
i = 0;
/* Loop through all LineItems */
while (item = XmlDomGetNodeListItem(xctx, litems, i))
{
/* Get the part */
part = XmlDomGetLastChild(xctx, item);
/* Get the attributes */
attrs = XmlDomGetAttrs(xctx, (xmlelemnode *)part);
/* Get the id attribute and its value */
id = XmlDomGetNamedItem(xctx, attrs, (oratext *)"Id");
idval = XmlDomGetNodeValue(xctx, id);
/* Keep only parts with id 37429158722 */
if (idval && (strlen((char *)idval) == 11 )
&& !strncmp((char *)idval, (char *)"37429158722", 11))
{
/* Get the quantity attribute and its value.*/
qty = XmlDomGetNamedItem(xctx, attrs, (oratext *)"Quantity");
qtyval = XmlDomGetNodeValue(xctx, qty);
/* Add the quantity to total_qty */
total_qty += atoi((char *)qtyval);
}
i++;
}
XmlFreeDocument(xctx, doc);
doc = (xmldocnode *)0;
}

Using the C API for XML

16-17

Common XMLType Operations in C

printf("Total quantity needed for part 37429158722 = %d\n", total_qty);
printf("Number of documents in table PURCHASEORDER = %d\n", numdocs);
/* Free Xml Ctx */
OCIXmlDbFreeXmlCtx(xctx);
/* Free envhp, svchp, errhp, stmthp */
free_oci_handles(ctx);
}

The output from compiling and running this C program is as follows:
Supports XML 1.0? : YES
Total quantity needed for part 37429158722 = 42
Number of documents in table PURCHASEORDER = 132

16-18 Oracle XML DB Developer's Guide

17
Using Oracle Data Provider for .NET with
Oracle XML DB
Oracle Data Provider for Microsoft .NET (ODP.NET) is an implementation of a data
provider for Oracle Database. It uses Oracle native APIs to offer fast and reliable access
to Oracle data and features from any .NET application. It also uses and inherits classes
and interfaces available in the Microsoft .NET Framework Class Library. ODP.NET
supports the following LOB data types natively with .NET: BLOB, CLOB, NCLOB, and
BFILE.
This chapter describes how to use ODP.NET with Oracle XML DB. It contains these
topics:
■

ODP.NET XML Support and Oracle XML DB

■

ODP.NET Sample Code

ODP.NET XML Support and Oracle XML DB
ODP.NET supports XML natively in the database, through Oracle XML DB. ODP.NET
XML support includes the following features:
■
■

■

Stores XML data natively in Oracle Database as XMLType.
Accesses relational and object-relational data as XML data from Oracle Database to
a Microsoft .NET environment, and processes the XML using Microsoft .NET
framework.
Saves changes to the database server using XML data.

For the .NET application developer, these features include the following:
■

Enhancements to the OracleCommand, OracleConnection, and
OracleDataReader classes. Provides the following XML-specific classes:
■

OracleXmlType

■

OracleXmlStream

■

OracleXmlQueryProperties

■

OracleXmlSaveProperties

ODP.NET Sample Code
Example 17–1 retrieves XMLType data from the database to .NET and outputs the
results:

Using Oracle Data Provider for .NET with Oracle XML DB 17-1

ODP.NET Sample Code

Example 17–1

Retrieve XMLType Data to .NET

//Create OracleCommand and query XMLType
OracleCommand xmlCmd = new OracleCommand();
poCmd.CommandText = "SELECT po FROM po_tab";
poCmd.Connection = conn;
// Execute OracleCommand and output XML results to an OracleDataReader
OracleDataReader poReader = poCmd.ExecuteReader();
// ODP.NET native XML data type object from Oracle XML DB
OracleXmlType poXml;
string str = ""; //read XML results
while (poReader.Read())
{
// Return OracleXmlType object of the specified XmlType column
poXml = poReader.GetOracleXmlType(0);
// Concatenate output for all the records
str = str + poXml.Value;
} //Output XML results to the screen
Console.WriteLine(str);

See Also: Oracle Data Provider for .NET Developer's Guide for
complete information about Oracle .NET support for Oracle
XML DB.

17-2 Oracle XML DB Developer's Guide

Part IV
Viewing Existing Data as XML
Part IV of this manual introduces you to ways you can view your existing data as
XML. It contains the following chapters:
■

Chapter 18, "Generating XML Data from the Database"

■

Chapter 19, "XMLType Views"

■

Chapter 20, "Accessing Data Through URIs"

18
Generating XML Data from the Database
This chapter describes Oracle XML DB features for generating (constructing) XML
data from relational data in the database. It describes the SQL/XML standard
functions and Oracle Database-provided functions and packages for generating XML
data from relational content.
This chapter contains these topics:
■

Overview of Generating XML Data From Oracle Database

■

Generating XML using SQL Functions

■

Generating XML using DBMS_XMLGEN

■

SYS_XMLGEN Oracle SQL Function

■

SYS_XMLAGG Oracle SQL Function

■

Guidelines for Generating XML with Oracle XML DB
See Also: Chapter 5, "Using XQuery with Oracle XML DB" for
information about constructing XML data using SQL/XML functions
XMLQuery and XMLTable

Overview of Generating XML Data From Oracle Database
You can generate XML data with Oracle Database in all of these ways:
■

■

Use standard SQL/XML functions. See "Generating XML using SQL Functions" on
page 18-2.
Use Oracle SQL functions. See the following sections:
■

XMLROOT Oracle SQL Function on page 18-18

■

XMLCOLATTVAL Oracle SQL Function on page 18-19

■

XMLCDATA Oracle SQL Function on page 18-21

■

■

■

■

SYS_XMLGEN Oracle SQL Function on page 18-46. This operates on rows,
generating XML documents.
SYS_XMLAGG Oracle SQL Function on page 18-54. This operates on groups
of rows, aggregating several XML documents into one.

Use PL/SQL package DBMS_XMLGEN. See "Generating XML using DBMS_
XMLGEN" on page 18-21.
Use a DBURIType instance to construct XML documents from database data. See
Chapter 20, "Accessing Data Through URIs".

Generating XML Data from the Database

18-1

Generating XML using SQL Functions

See Also:
■

Chapter 3, "Using Oracle XML DB"

■

Chapter 11, "Transforming and Validating XMLType Data"

■

Chapter 13, "PL/SQL APIs for XMLType"

■

Chapter 15, "Java DOM API for XMLType"

Generating XML using SQL Functions
This section describes SQL functions that you can use to construct XML data. Most of
these functions belong to the SQL/XML standard.
■

XMLELEMENT and XMLATTRIBUTES SQL/XML Functions on page 18-3

■

XMLFOREST SQL/XML Function on page 18-9

■

XMLCONCAT SQL/XML Function on page 18-11

■

XMLAGG SQL/XML Function on page 18-12

■

XMLPI SQL/XML Function on page 18-15

■

XMLCOMMENT SQL/XML Function on page 18-16

■

XMLSERIALIZE SQL/XML Function on page 18-16

■

XMLPARSE SQL/XML Function on page 18-17

The standard XML-generation functions are also known as SQL/XML publishing
functions.
You can also construct XML data using the SQL/XML function XMLQuery. The use of
XMLQuery is not limited to publishing XML data. It is very general and is referred to
in this book as a SQL/XML query and access function.
This standardization process is ongoing. Please refer to http://www.sqlx.org for
the latest information about SQL/XML functions, including XMLQuery and
XMLTable.
Other XML-generating SQL functions presented in this section are Oracle-specific (not
part of the SQL/XML standard):
■

XMLROOT Oracle SQL Function on page 18-18.

■

XMLCOLATTVAL Oracle SQL Function on page 18-19.

■

XMLCDATA Oracle SQL Function on page 18-21.

■

■

SYS_XMLGEN Oracle SQL Function on page 18-46. This operates on relational
rows, generating XML documents.
SYS_XMLAGG Oracle SQL Function on page 18-54. This operates on groups of
relational rows, aggregating several XML documents into one.

All of the XML-generation SQL functions convert scalars and user-defined data-type
instances to their canonical XML format. In this canonical mapping, user-defined
data-type attributes are mapped to XML elements.

18-2 Oracle XML DB Developer's Guide

Generating XML using SQL Functions

See Also:
■

■

Chapter 5, "Using XQuery with Oracle XML DB" for information
about constructing XML data using SQL/XML function
XMLQuery
Oracle Database SQL Language Reference for information about
Oracle support for the SQL/XML standard

XMLELEMENT and XMLATTRIBUTES SQL/XML Functions
You use SQL/XML standard function XMLElement to construct XML elements from
relational data. It takes as arguments an element name, an optional collection of
attributes for the element, and zero or more additional arguments that make up the
element content. It returns an XMLType instance.
Figure 18–1 XMLELEMENT Syntax
ENTITYESCAPING
NOENTITYESCAPING
XMLELEMENT

(

AS

NAME
identifier

,

XML_attributes_clause

,

c_alias

value_expr
)

EVALNAME

value_expr

For an explanation of keywords ENTITYESCAPING and NOENTITYESCAPING, see
"Escaping Characters in Generated XML Data" on page 18-4. These keywords are
Oracle extensions to standard SQL/XML functions XMLElement and
XMLAttributes.
The first argument to function XMLElement defines an identifier that names the root
XML element to be created. The root-element identifier argument can be defined using
a literal identifier (identifier, in Figure 18–1) or by EVALNAME followed by an
expression (value_expr) that evaluates to an identifier. However it is defined, the
identifier must not be NULL or else an error is raised. The possibility of using
EVALNAME is an Oracle extension to standard SQL/XML function XMLElement.
The optional XML-attributes-clause argument of function XMLElement specifies
the attributes of the root element to be generated. Figure 18–2 shows the syntax of this
argument.
In addition to the optional XML-attributes-clause argument, function
XMLElement accepts zero or more value_expr arguments that make up the content
of the root element (child elements and text content). If an XML-attributes-clause
argument is also present, these content arguments must follow the
XML-attributes-clause argument. Each of the content-argument expressions is
evaluated, and the result is converted to XML format. If a value argument evaluates to
NULL, then no content is created for that argument.
The optional XML-attributes-clause argument uses SQL/XML standard function
XMLAttributes to specify the attributes of the root element. Function
XMLAttributes can be used only in a call to function XMLElement. It cannot be used
on its own.

Generating XML Data from the Database

18-3

Generating XML using SQL Functions

Figure 18–2 XMLAttributes Clause Syntax (XMLATTRIBUTES)
XMLATTRIBUTES

ENTITYESCAPING

SCHEMACHECK

NOENTITYESCAPING

NOSCHEMACHECK

(

,
AS

c_alias

value_expr

)

For an explanation of keywords ENTITYESCAPING and NOENTITYESCAPING, see
"Escaping Characters in Generated XML Data" on page 18-4. These keywords are
Oracle extensions to standard SQL/XML functions XMLElement and
XMLAttributes.
Keywords SCHEMACHECK and NOSCHEMACHECK determine whether or not a run-time
check is made of the generated attributes, to see if any of them specify a schema
location that corresponds to an XML schema that is registered with Oracle XML DB,
and, if so, to try to generate XML schema-based XML data accordingly. The default
behavior is that provided by NOSCHEMACHECK: no check is made. In releases prior to
11g Release 2 (11.2), the default behavior is to perform the check. Keyword
SCHEMACHECK can be used to obtain backward compatibility.
Note that a similar check is always made at compile time, regardless of the presence or
absence of NOSCHEMACHECK. This means, in particular, that if you use a string literal to
specify an XML schema location attribute value, then a (compile-time) check is made,
and, if appropriate, XML schema-based data is generated accordingly.
Keywords SCHEMACHECK and NOSCHEMACHECK are Oracle extensions to standard
SQL/XML function XMLAttributes.
If a view is created to generate XML data, function
XMLAttributes is used to add XML-schema location references, and
the target XML schema has not yet been registered with Oracle
XML DB, then the XML data generated is not XML schema-based. If
the XML schema is subsequently registered, then XML data generated
thereafter is also not XML-schema-based. To create XML schema-based
data, you must recompile the view.

Note:

Argument XML-attributes-clause itself contains one or more value_expr
expressions as arguments to function XMLAttributes. These are evaluated to obtain
the values for the attributes of the root element. (Do not confuse these value_expr
arguments to function XMLAttributes with the value_expr arguments to function
XMLElement, which specify the content of the root element.) The optional AS c_
alias clause for each value_expr specifies that the attribute name is c_alias,
which can be either a string literal or EVALNAME followed by an expression that
evaluates to a string literal. (The possibility of using EVALNAME is an Oracle extension
to standard SQL/XML function XMLElement.)
If an attribute value expression evaluates to NULL, then no corresponding attribute is
created. The data type of an attribute value expression cannot be an object type or a
collection.

Escaping Characters in Generated XML Data
As specified by the SQL/XML standard, characters in explicit identifiers are not
escaped in any way – it is up to you to ensure that valid XML names are used. This
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Generating XML using SQL Functions

applies to all SQL/XML functions. In particular, it applies to the root-element
identifier of XMLElement (identifier, in Figure 18–1) and to attribute identifier
aliases named with AS clauses of XMLAttributes (see Figure 18–2).
However, other XML data that is generated is escaped, by default, to ensure that only
valid XML NameChar characters are generated. As part of generating a valid XML
element or attribute name from a SQL identifier, each character that is disallowed in an
XML name is replaced with an underscore character (_), followed by the hexadecimal
Unicode representation of the original character, followed by a second underscore
character. For example, the colon character (:) is escaped by replacing it with _003A_,
where 003A is the hexadecimal Unicode representation.
Escaping applies to characters in the evaluated value_expr arguments to all
SQL/XML functions, including XMLElement and XMLAttributes. It applies also to
the characters of an attribute identifier that is defined implicitly from an
XMLAttributes attribute value expression that is not followed by an AS clause: the
escaped form of the SQL column name is used as the name of the attribute.
In some cases, you might not need or want character escaping. If you know, for
example, that the XML data being generated is well-formed, then you can save some
processing time by inhibiting escaping. You can do that by specifying the keyword
NOENTITYESCAPING for SQL/XML functions XMLElement and XMLAttributes.
Keyword ENTITYESCAPING imposes escaping, which is the default behavior.
Keywords NOENTITYESCAPING and ENTITYESCAPING are Oracle extensions to
standard SQL/XML functions XMLElement and XMLAttributes.

Formatting of XML Dates and Timestamps
The XML Schema standard specifies that dates and timestamps in XML data be in
standard formats. XML generation functions in Oracle XML DB produce XML dates
and timestamps according to this standard.
In releases prior to Oracle Database 10g Release 2, the database settings for date and
timestamp formats, not the XML Schema standard formats, were used for XML. You
can reproduce this previous behavior by setting the database event 19119, level 0x8, as
follows:
ALTER SESSION SET EVENTS '19119 TRACE NAME CONTEXT FOREVER, LEVEL 0x8';

If you must otherwise produce a nonstandard XML date or timestamp, use SQL
function to_char – see Example 18–1.
See Also:

http://www.w3.org/TR/2004/REC-xmlschema-2-20041028/d
atatypes.html#isoformats for the XML Schema specification of
XML date and timestamp formats

XMLElement Examples
This section provides examples that use SQL/XML function XMLElement.
Example 18–1 uses XMLElement to generate an XML date with a format that is
different from the XML Schema standard date format.
Example 18–1

XMLELEMENT: Formatting a Date

-- With standard XML date format:
SELECT XMLElement("Date", hire_date)
FROM hr.employees
WHERE employee_id = 203;

Generating XML Data from the Database

18-5

Generating XML using SQL Functions

XMLELEMENT("DATE",HIRE_DATE)
---------------------------2002-06-07
1 row selected.
-- With an alternative date format:
SELECT XMLElement("Date", to_char(hire_date))
FROM hr.employees
WHERE employee_id = 203;
XMLELEMENT("DATE",TO_CHAR(HIRE_DATE))
------------------------------------07-JUN-02
1 row selected.

Example 18–2 uses XMLElement to generate an Emp element for each employee, with
the employee name as the content.
Example 18–2

XMLELEMENT: Generating an Element for Each Employee

SELECT e.employee_id,
XMLELEMENT ("Emp", e.first_name ||' '|| e.last_name) AS "RESULT"
FROM hr.employees e
WHERE employee_id > 200;

This query produces the following typical result:
EMPLOYEE_ID
----------201
202
203
204
205
206

RESULT
----------------------------------Michael Hartstein
Pat Fay
Susan Mavris
Hermann Baer
Shelley Higgins
William Gietz

6 rows selected.

SQL/XML function XMLElement can also be nested, to produce XML data with a
nested structure.
Example 18–3 uses XMLElement to generate an Emp element for each employee, with
child elements that provide the employee name and hire date.
Example 18–3

XMLELEMENT: Generating Nested XML

SELECT XMLElement("Emp",
XMLElement("name", e.first_name ||' '|| e.last_name),
XMLElement("hiredate", e.hire_date)) AS "RESULT"
FROM hr.employees e
WHERE employee_id > 200;

This query produces the following typical XML result:
RESULT
----------------------------------------------------------------------Michael Hartstein2004-02-17
Pat Fay2005-08-17

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Generating XML using SQL Functions

Susan Mavris2002-06-07
Hermann Baer2002-06-07
Shelley Higgins2002-06-07
William Gietz2002-06-07
6 rows selected.

Example 18–4 uses XMLElement to generate an Emp element for each employee, with
attributes id and name.
Example 18–4
Name

XMLELEMENT: Generating Employee Elements with Attributes ID and

SELECT XMLElement("Emp", XMLAttributes(
e.employee_id as "ID",
e.first_name ||' ' || e.last_name AS "name"))
AS "RESULT"
FROM hr.employees e
WHERE employee_id > 200;

This query produces the following typical XML result fragment:
RESULT
----------------------------------------------





6 rows selected.

As mentioned in "Escaping Characters in Generated XML Data" on page 18-4,
characters in the root-element name and the names of any attributes defined by AS
clauses are not escaped. Characters in an identifier name are escaped only if the name
is created from an evaluated expression (such as a column reference).
Example 18–5 shows that, with XML data constructed using XMLElement, the
root-element name and the attribute name are not escaped. Invalid XML is produced
because greater-than sign (>) and a comma (,) are not allowed in XML element and
attribute names.
Example 18–5

XMLELEMENT: Characters in Generated XML Are Not Escaped

SELECT XMLElement("Emp->Special",
XMLAttributes(e.last_name || ', ' || e.first_name
AS "Last,First"))
AS "RESULT"
FROM hr.employees e
WHERE employee_id = 201;

This query produces the following result, which is not well-formed XML:
RESULT
-------------------------------------------------------------------Special Last,First="Hartstein, Michael">Special>
1 row selected.

A full description of character escaping is included in the SQL/XML standard.
Generating XML Data from the Database

18-7

Generating XML using SQL Functions

Example 18–6 illustrates the use of namespaces to create an XML schema-based
document. Assuming that an XML schema
"http://www.oracle.com/Employee.xsd" exists and has no target namespace,
the query in Example 18–6 creates an XMLType instance conforming to that schema:
Example 18–6
Namespaces

Creating a Schema-Based XML Document using XMLELEMENT with

SELECT XMLElement("Employee",
XMLAttributes('http://www.w3.org/2001/XMLSchema' AS
"xmlns:xsi",
'http://www.oracle.com/Employee.xsd' AS
"xsi:nonamespaceSchemaLocation"),
XMLForest(employee_id, last_name, salary)) AS "RESULT"
FROM hr.employees
WHERE department_id = 10;

This creates the following XML document that conforms to XML schema
Employee.xsd. (The result is shown here pretty-printed, for clarity.)
RESULT
----------------------------------------------------------------------------
200
Whalen
4400

1 row selected.

Example 18–7 uses XMLElement to generate an XML document with employee and
department information, using data from sample database schema table
hr.departments.
Example 18–7
Instance

XMLELEMENT: Generating an Element from a User-Defined Data-Type

CREATE OR REPLACE TYPE emp_t AS OBJECT ("@EMPNO" NUMBER(4),
ENAME VARCHAR2(10));
CREATE OR REPLACE TYPE emplist_t AS TABLE OF emp_t;
CREATE OR REPLACE TYPE dept_t AS OBJECT ("@DEPTNO" NUMBER(2),
DNAME VARCHAR2(14),
EMP_LIST emplist_t);
SELECT XMLElement("Department",
dept_t(department_id,
department_name,
cast(MULTISET
(SELECT employee_id, last_name
FROM hr.employees e
WHERE e.department_id = d.department_id)
AS emplist_t)))
AS deptxml
FROM hr.departments d
WHERE d.department_id = 10;

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Generating XML using SQL Functions

This produces an XML document which contains the Department element and the
canonical mapping of type dept_t.
DEPTXML
------------

ACCOUNTING


CLARK


KING


MILLER




1 row selected.

XMLFOREST SQL/XML Function
You use SQL/XML standard function XMLForest to construct a forest of XML
elements. Its arguments are expressions to be evaluated, with optional aliases.
Figure 18–3 describes the XMLForest syntax.
Figure 18–3 XMLFOREST Syntax
,
c_alias
AS
EVALNAME
XMLFOREST

(

value_expr

value_expr
)

Each of the value expressions (value_expr in Figure 18–3) is converted to XML
format, and, optionally, identifier c_alias is used as the attribute identifier (c_
alias can be a string literal or EVALNAME followed by an expression that evaluates to
a string literal). The possibility of using EVALNAME is an Oracle extension to standard
SQL/XML function XMLForest.
For an object type or collection, the AS clause is required. For other types, the AS clause
is optional. For a given expression, if the AS clause is omitted, then characters in the
evaluated value expression are escaped to form the name of the enclosing tag of the
element. The escaping is as defined in "Escaping Characters in Generated XML Data"
on page 18-4. If the value expression evaluates to NULL, then no element is created for
that expression.
Example 18–8 uses XMLElement and XMLForest to generate an Emp element for each
employee, with a name attribute and with child elements containing the employee hire
date and department as the content.
Example 18–8

XMLFOREST: Generating Elements with Attribute and Child Elements

SELECT XMLElement("Emp",

Generating XML Data from the Database

18-9

Generating XML using SQL Functions

XMLAttributes(e.first_name ||' '|| e.last_name AS "name"),
XMLForest(e.hire_date, e.department AS "department"))
AS "RESULT"
FROM employees e WHERE e.department_id = 20;

(The WHERE clause is used here to keep the example brief.) This query produces the
following XML result:
RESULT
------------------------------------
2004-02-17
20


2005-08-17
20

2 rows selected.

See Also: Example 18–20, "XMLCOLATTVAL: Generating Elements
with Attribute and Child Elements"

Example 18–9 uses XMLForest to generate hierarchical XML data from user-defined
data-type instances.
Example 18–9
Instance

XMLFOREST: Generating an Element from a User-Defined Data-Type

SELECT XMLForest(
dept_t(department_id,
department_name,
cast(MULTISET
(SELECT employee_id, last_name
FROM hr.employees e WHERE e.department_id = d.department_id)
AS emplist_t))
AS "Department")
AS deptxml
FROM hr.departments d
WHERE department_id=10;

This produces an XML document with element Department containing attribute
DEPTNO and child element DNAME.
DEPTXML
--------------------------------
Administration


Whalen



1 row selected.

You may want to compare this example with Example 18–7 and Example 18–25.

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Generating XML using SQL Functions

XMLCONCAT SQL/XML Function
You use SQL/XML standard function XMLConcat to construct an XML fragment by
concatenating multiple XMLType instances. Figure 18–4 shows the XMLConcat syntax.
Function XMLConcat has two forms:
■

■

The first form takes as argument an XMLSequenceType value, which is a varray
of XMLType instances, and returns a single XMLType instance that is the
concatenation of all of the elements of the varray. This form is useful to collapse
lists of XMLType instances into a single instance.
The second form takes an arbitrary number of XMLType instances and
concatenates them together. If one of the values is NULL, then it is ignored in the
result. If all the values are NULL, then the result is NULL. This form is used to
concatenate arbitrary number of XMLType instances in the same row. Function
XMLAgg can be used to concatenate XMLType instances across rows.

Figure 18–4 XMLCONCAT Syntax
,
XMLCONCAT

(

XMLType_instance

)

Example 18–10 uses SQL/XML function XMLConcat to return a concatenation of
XMLType instances from an XMLSequenceType value (a varray of XMLType
instances).
Example 18–10 XMLCONCAT: Concatenating XMLType Instances from a Sequence
SELECT XMLSerialize(
CONTENT
XMLConcat(XMLSequenceType(
XMLType('1236'),
XMLType('Widget'),
XMLType('29.99')))
AS CLOB)
AS "RESULT"
FROM DUAL;

This query returns a single XML fragment. (The result is shown here pretty-printed,
for clarity.)
RESULT
--------------1236
Widget
29.99
1 row selected.

Example 18–11 uses XMLConcat to create and concatenate XML elements for
employee first and the last names.
Example 18–11 XMLCONCAT: Concatenating XML Elements
SELECT XMLConcat(XMLElement("first", e.first_name),
XMLElement("last", e.last_name))
AS "RESULT"
FROM employees e;

Generating XML Data from the Database 18-11

Generating XML using SQL Functions

This query produces the following XML fragment:
RESULT
-------------------------------------------DenRaphaely
AlexanderKhoo
ShelliBaida
SigalTobias
GuyHimuro
KarenColmenares
6 rows selected.

XMLAGG SQL/XML Function
You use SQL/XML standard function XMLAgg to construct a forest of XML elements
from a collection of XML elements—it is an aggregate function.
Figure 18–5 XMLAGG Syntax
order_by_clause
XMLAGG

(

XMLType_instance

)

Figure 18–5 describes the XMLAgg syntax, where the order_by_clause is the
following:
ORDER BY [list of: expr [ASC|DESC] [NULLS {FIRST|LAST}]]

Numeric literals are not interpreted as column positions. For example, ORDER BY 1
does not mean order by the first column. Instead, numeric literals are interpreted as
any other literals.
As with SQL/XML function XMLConcat, any arguments whose value is NULL are
dropped from the result. SQL/XML function XMLAgg is similar to Oracle SQL function
sys_XMLAgg, but XMLAgg returns a forest of nodes and it does not accept an
XMLFormat parameter.
SQL/XML function XMLAgg can be used to concatenate XMLType instances across
multiple rows. It also accepts an optional ORDER BY clause, to order the XML values
being aggregated. Function XMLAgg produces one aggregated XML result for each
group. If there is no group by specified in the query, then it returns a single aggregated
XML result for all the rows of the query.
Example 18–12 uses SQL/XML functions XMLAgg and XMLElement to construct a
Department element that contains Employee elements that have employee job ID
and last name as their contents. It also orders the Employee elements in the
department by employee last name. (The result is shown pretty-printed, for clarity.)
Example 18–12 XMLAGG: Generating a Department Element with Child Employee
Elements
SELECT XMLElement("Department", XMLAgg(XMLElement("Employee",
e.job_id||' '||e.last_name)
ORDER BY e.last_name))
AS "Dept_list"
FROM hr.employees e
WHERE e.department_id = 30 OR e.department_id = 40;
Dept_list

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Generating XML using SQL Functions

-----------------
PU_CLERK Baida
PU_CLERK Colmenares
PU_CLERK Himuro
PU_CLERK Khoo
HR_REP Mavris
PU_MAN Raphaely
PU_CLERK Tobias

1 row selected.

The result is a single row, because XMLAgg aggregates the employee rows.
Example 18–13 shows how to use the GROUP BY clause to group the returned set of
rows into multiple groups, forming multiple Department elements. (The result is
shown here pretty-printed, for clarity.)
Example 18–13 XMLAGG: Using GROUP BY to Generate Multiple Department Elements
SELECT XMLElement("Department", XMLAttributes(department_id AS "deptno"),
XMLAgg(XMLElement("Employee", e.job_id||' '||e.last_name)))
AS "Dept_list"
FROM hr.employees e
GROUP BY e.department_id;
Dept_list
-----------------
PU_MAN Raphaely
PU_CLERK Colmenares
PU_CLERK Himuro
PU_CLERK Tobias
PU_CLERK Baida
PU_CLERK Khoo

HR_REP Mavris

2 rows selected.

You can order the employees within each department by using the ORDER BY clause
inside the XMLAgg expression.
Within the ORDER BY clause, Oracle Database does not
interpret number literals as column positions, as it does in other
uses of this clause.

Note:

Function XMLAgg can be used to reflect the hierarchical nature of some relationships
that exist in tables. Example 18–14 generates a department element for department 30.
Within this element is a child element emp for each employee of the department.
Within each employee element is a dependent element for each dependent of that
employee.

Generating XML Data from the Database 18-13

Generating XML using SQL Functions

Example 18–14 XMLAGG: Generating Nested Elements
SELECT last_name, employee_id FROM employees WHERE department_id = 30;
LAST_NAME
EMPLOYEE_ID
------------------------- ----------Raphaely
114
Khoo
115
Baida
116
Tobias
117
Himuro
118
Colmenares
119
6 rows selected.

A dependents table holds the dependents of each employee.
CREATE TABLE hr.dependents (id NUMBER(4) PRIMARY KEY,
employee_id NUMBER(4),
name VARCHAR2(10));
Table created.
INSERT INTO dependents VALUES (1, 114, 'MARK');
1 row created.
INSERT INTO dependents VALUES (2, 114, 'JACK');
1 row created.
INSERT INTO dependents VALUES (3, 115, 'JANE');
1 row created.
INSERT INTO dependents VALUES (4, 116, 'HELEN');
1 row created.
INSERT INTO dependents VALUES (5, 116, 'FRANK');
1 row created.
COMMIT;
Commit complete.

The following query generates the XML data for a department that contains the
information about dependents. (The result is shown here pretty-printed, for clarity.)
SELECT
XMLElement(
"Department",
XMLAttributes(d.department_name AS "name"),
(SELECT
XMLAgg(XMLElement("emp",
XMLAttributes(e.last_name AS name),
(SELECT XMLAgg(XMLElement("dependent",
XMLAttributes(de.name AS "name")))
FROM dependents de
WHERE de.employee_id = e.employee_id)))
FROM employees e
WHERE e.department_id = d.department_id)) AS "dept_list"
FROM departments d
WHERE department_id = 30;
dept_list
-------------------------------------------------------------------------------






18-14 Oracle XML DB Developer's Guide

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1 row selected.

XMLPI SQL/XML Function
You use SQL/XML standard function XMLPI to construct an XML processing
instruction (PI). Figure 18–6 shows the syntax:
Figure 18–6 XMLPI Syntax
NAME
identifier
XMLPI

,

value_expr

(

)
EVALNAME

value_expr

Argument value_expr is evaluated, and the string result is appended to the optional
identifier (identifier), separated by a space. This concatenation is then enclosed
between "" to create the processing instruction. That is, if
string-result is the result of evaluating value_expr, then the generated
processing instruction is . If string-result is
the empty string, '', then the function returns .
As an alternative to using keyword NAME followed by a literal string identifier, you
can use keyword EVALNAME followed by an expression that evaluates to a string to be
used as the identifier. The possibility of using EVALNAME is an Oracle extension to
standard SQL/XML function XMLPI.
An error is raised if the constructed XML is not a legal XML processing instruction. In
particular:
■

identifier must not be the word "xml" (uppercase, lowercase, or mixed case).

■

string-result must not contain the character sequence "?>".

Function XMLPI returns an instance of XMLType. If string-result is NULL, then it
returns NULL.
Example 18–15 uses XMLPI to generate a simple processing instruction.
Example 18–15 Using SQL/XML Function XMLPI
SELECT XMLPI(NAME "OrderAnalysisComp", 'imported, reconfigured, disassembled')
AS pi FROM DUAL;

This results in the following output:
PI
---------------------------------------------------------
1 row selected.

Generating XML Data from the Database 18-15

Generating XML using SQL Functions

XMLCOMMENT SQL/XML Function
You use SQL/XML standard function XMLComment to construct an XML comment.
Figure 18–7 shows the syntax:
Figure 18–7 XMLComment Syntax
XMLCOMMENT

(

value_expr

)

Argument value_expr is evaluated to a string, and the result is used as the body of
the generated XML comment. The result is thus , where
string-result is the string result of evaluating value_expr. If string-result
is the empty string, then the comment is empty: .
An error is raised if the constructed XML is not a legal XML comment. In particular,
string-result must not contain two consecutive hyphens (-): "--".
Function XMLComment returns an instance of XMLType. If string-result is NULL,
then the function returns NULL.
Example 18–16 uses XMLComment to generate a simple XML comment.
Example 18–16 Using SQL/XML Function XMLCOMMENT
SELECT XMLComment('This is a comment') AS cmnt FROM DUAL;

This query results in the following output:
CMNT
-------------------------

XMLSERIALIZE SQL/XML Function
You use SQL/XML standard function XMLSerialize to obtain a string or LOB
representation of XML data.
Figure 18–8 shows the syntax of XMLSerialize:
Figure 18–8 XMLSerialize Syntax
AS

DOCUMENT
XMLSERIALIZE

(

datatype

value_expr
CONTENT

ENCODING

NO

xml_encoding_spec

VERSION

string_literal

INDENT
SIZE

INDENT

=

number

HIDE
DEFAULTS
SHOW
)

Argument value_expr is evaluated, and the resulting XMLType instance is serialized
to produce the content of the created string or LOB. If present1, the specified
datatype must be one of the following (the default data type is CLOB):
■

VARCHAR2(N), where N is the size in bytes (limit 4000)

18-16 Oracle XML DB Developer's Guide

Generating XML using SQL Functions

■

CLOB

■

BLOB

If you specify DOCUMENT, then the result of evaluating value_expr must be a
well-formed document. In particular, it must have a single root. If the result is not a
well-formed document, then an error is raised. If you specify CONTENT, however, then
the result of value_expr is not checked for being well-formed.
If value_expr evaluates to NULL or to the empty string (''), then function
XMLSerialize returns NULL.
The ENCODING clause specifies the character encoding for XML data that is serialized
as a BLOB instance. xml_encoding_spec is an XML encoding declaration
(encoding="..."). If datatype is BLOB and you specify an ENCODING clause, then
the output is encoded as specified, and xml_encoding_spec is added to the prolog
to indicate the BLOB encoding. If you specify an ENCODING clause with a datatype
other than BLOB, then an error is raised.
If you specify the VERSION, then that version is used in the XML declaration ().
If you specify NO INDENT, then all insignificant whitespace is stripped, so that it does
not appear in the output. If you specify INDENT SIZE = N, where N is a whole
number, then the output is pretty-printed using a relative indentation of N spaces. If N is
0, then pretty-printing inserts a newline character after each element, placing each
element on a line by itself, but there is no other insignificant whitespace in the output.
If you specify INDENT without a SIZE specification, then 2-space indenting is used. If
you specify neither NO INDENT nor INDENT, then the behavior (pretty-printing or
not) is indeterminate.
HIDE DEFAULTS and SHOW DEFAULTS apply only to XML schema-based data. If you
specify SHOW DEFAULTS and the input data is missing any optional elements or
attributes for which the XML schema defines default values, then those elements or
attributes are included in the output with their default values. If you specify HIDE
DEFAULTS, then no such elements or attributes are included in the output. HIDE
DEFAULTS is the default behavior.
Example 18–17 uses XMLSerialize to produce a CLOB instance containing serialized
XML data.
Example 18–17 Using SQL/XML Function XMLSERIALIZE
SELECT XMLSerialize(DOCUMENT XMLType('143598') AS CLOB)
AS xmlserialize_doc FROM DUAL;

This results in the following output:
XMLSERIALIZE_DOC
------------------143598

XMLPARSE SQL/XML Function
You use SQL/XML standard function XMLParse to parse a string containing XML
data and construct a corresponding XMLType instance. Figure 18–9 shows the syntax:

1

The SQL/XML standard requires argument data-type to be present, but it is optional in the
Oracle XML DB implementation of the standard, for ease of use.

Generating XML Data from the Database 18-17

Generating XML using SQL Functions

Figure 18–9 XMLParse Syntax
WELLFORMED

DOCUMENT
XMLPARSE

(

value_expr

)

CONTENT

Argument value_expr is evaluated to produce the string that is parsed. If you
specify DOCUMENT, then value_expr must correspond to a singly rooted, well-formed
XML document. If you specify CONTENT, then value_expr need only correspond to a
well-formed XML fragment (it need not be singly rooted).
Keyword WELLFORMED is an Oracle XML DB extension to the SQL/XML standard.
When you specify WELLFORMED, you are informing the parser that argument value_
expr is well-formed, so Oracle XML DB does not check to ensure that it is
well-formed.
Function XMLParse returns an instance of XMLType. If value_expr evaluates to
NULL, then the function returns NULL.
Example 18–18 uses XMLParse to parse a string of XML code and produce an
XMLType instance.
Example 18–18 Using SQL/XML Function XMLPARSE
SELECT XMLParse(CONTENT
'124 
 Acme Enterprises
32987457
'
WELLFORMED)
AS po FROM DUAL d;

This results in the following output:
PO
----------------------------------------------124 
Acme Enterprises
32987457


See Also: http://www.w3.org/TR/REC-xml/, Extensible Markup
Language (XML) 1.0, for the definition of well-formed XML documents
and fragments

XMLROOT Oracle SQL Function
Oracle SQL function XMLRoot was at one time part of the SQL/XML standard, but it
is deprecated as a standard function as of SQL/XML 2005. It remains available in Oracle
XML DB, as an Oracle SQL function.
You use XMLRoot to add a VERSION property, and optionally a STANDALONE
property, to the root information item of an XML value. Typically, this is done to
ensure data-model compliance. Figure 18–10 shows the syntax of XMLRoot:

18-18 Oracle XML DB Developer's Guide

Generating XML using SQL Functions

Figure 18–10

XMLRoot Syntax
YES
,

STANDALONE

NO

value_expr
XMLROOT

(

value_expr

,

NO
VALUE

VERSION

)
NO

VALUE

The first argument, xml-expression, is evaluated, and the indicated properties
(VERSION, STANDALONE) and their values are added to a new prolog for the resulting
XMLType instance. If the evaluated xml-expression already contains a prolog, then
an error is raised.
Second argument string-valued-expression (which follows keyword VERSION)
is evaluated, and the resulting string is used as the value of the prolog version
property. The value of the prolog standalone property (lowercase) is taken from the
optional third argument STANDALONE YES or NO value. If NOVALUE is used for
VERSION, then "version=1.0" is used in the resulting prolog. If NOVALUE is used
for STANDALONE, then the standalone property is omitted from the resulting prolog.
Function XMLRoot returns an instance of XMLType. If first argument
xml-expression evaluates to NULL, then the function returns NULL.
Example 18–19 uses XMLRoot to add an XML declaration with version and
standalone attributes.
Example 18–19 Using Oracle SQL Function XMLRoot
SELECT XMLRoot(XMLType('143598'), VERSION '1.0', STANDALONE YES)
AS xmlroot FROM DUAL;

This results in the following output:
XMLROOT
-------------------------------------
143598
1 row selected.

XMLCOLATTVAL Oracle SQL Function
Oracle SQL function XMLColAttVal generates a forest of XML column elements
containing the values of the arguments passed in. This function is an Oracle extension
to the SQL/XML ANSI-ISO standard functions. Figure 18–11 shows the
XMLColAttVal syntax.
Figure 18–11

XMLCOLATTVAL Syntax
,
c_alias
AS
EVALNAME

XMLCOLATTVAL

(

value_expr

value_expr
)

The arguments are used as the values of the name attribute of the column element.
The c_alias values are used as the attribute identifiers.
Generating XML Data from the Database 18-19

Generating XML using SQL Functions

As an alternative to using keyword AS followed by a literal string c_alias, you can
use AS EVALNAME followed by an expression that evaluates to a string to be used as
the attribute identifier.
Because argument values value_expr are used only as attribute values, they need not
be escaped in any way. This is in contrast to function XMLForest. It means that you
can use XMLColAttVal to transport SQL columns and values without escaping.
Example 18–20 uses XMLColAttVal to generate an Emp element for each employee,
with a name attribute, and with column elements that have the employee hire date
and department as the content.
Example 18–20 XMLCOLATTVAL: Generating Elements with Attribute and Child
Elements
SELECT XMLElement("Emp",
XMLAttributes(e.first_name ||' '||e.last_name AS "fullname" ),
XMLColAttVal(e.hire_date, e.department_id AS "department"))
AS "RESULT"
FROM hr.employees e
WHERE e.department_id = 30;

This query produces the following XML result. (The result is shown here
pretty-printed, for clarity.)
RESULT
----------------------------------------------------------
2002-12-07
30


2003-05-18
30


2005-12-24
30


2005-07-24
30


2006-11-15
30


2007-08-10
30

6 rows selected.

See Also: Example 18–8, "XMLFOREST: Generating Elements with
Attribute and Child Elements"

18-20 Oracle XML DB Developer's Guide

Generating XML using DBMS_XMLGEN

XMLCDATA Oracle SQL Function
You use Oracle SQL function XMLCDATA to generate an XML CDATA section.
Figure 18–12 shows the syntax:
Figure 18–12
XMLCDATA

XMLCDATA Syntax
(

value_expr

)

Argument value_expr is evaluated to a string, and the result is used as the body of
the generated XML CDATA section, , where
string-result is the result of evaluating value_expr. If string-result is the
empty string, then the CDATA section is empty: .
An error is raised if the constructed XML is not a legal XML CDATA section. In
particular, string-result must not contain two consecutive right brackets (]): "]]".
Function XMLCDATA returns an instance of XMLType. If string-result is NULL,
then the function returns NULL.
Example 18–21 uses XMLCDATA to generate an XML CDATA section.
Example 18–21 Using Oracle SQL Function XMLCDATA
SELECT XMLElement("PurchaseOrder",
XMLElement("Address",
XMLCDATA('100 Pennsylvania Ave.'),
XMLElement("City", 'Washington, D.C.')))
AS RESULT FROM DUAL;

This results in the following output. (The result is shown here pretty-printed, for
clarity.)
RESULT
-------------------------


Washington, D.C.



Generating XML using DBMS_XMLGEN
PL/SQL package DBMS_XMLGEN creates XML documents from SQL query results. It
retrieves an XML document as a CLOB or XMLType value.
It provides a fetch interface, whereby you can specify the maximum number of rows to
retrieve and the number of rows to skip. For example, the first fetch could retrieve a
maximum of ten rows, skipping the first four. This is especially useful for pagination
requirements in Web applications.
Package DBMS_XMLGEN also provides options for changing tag names for ROW,
ROWSET, and so on. The parameters of the package can restrict the number of rows
retrieved and the enclosing tag names.

Generating XML Data from the Database 18-21

Generating XML using DBMS_XMLGEN

See Also:
■
■

Oracle Database PL/SQL Packages and Types Reference
Oracle XML Developer's Kit Programmer's Guide (compare
OracleXMLQuery with DBMS_XMLGEN)

Using PL/SQL Package DBMS_XMLGEN
Figure 18–13 illustrates how to use package DBMS_XMLGEN. The steps are as follows:
1.

Get the context from the package by supplying a SQL query and calling PL/SQL
function newContext.

2.

Pass the context to all procedures or functions in the package to set the various
options. For example, to set the ROW element name, use setRowTag(ctx), where
ctx is the context got from the previous newContext call.

3.

Get the XML result, using PL/SQL function getXML or getXMLType. By setting
the maximum number of rows to be retrieved for each fetch using PL/SQL
procedure setMaxRows, you can call either of these functions repeatedly,
retrieving up to the maximum number of rows for each call. These functions
return XML data (as a CLOB value and as an instance of XMLType, respectively),
unless there are no rows retrieved. In that case, these functions return NULL. To
determine how many rows were retrieved, use PL/SQL function
getNumRowsProcessed.

4.

You can reset the query to start again and repeat step 3.

5.

Call PL/SQL procedure closeContext to free up any previously allocated
resources.

Figure 18–13 Using PL/SQL Package DBMS_XMLGEN

Using DBMS_XMLGEN to Generate XML
REGISTER
Query

set
the options

bind
values

User, browser,
client or
application

fetch
XML

Generated
XML
as DOM
User, browser,
client or
application

close

Generated
XML
as String

In conjunction with a SQL query, PL/SQL method DBMS_XMLGEN.getXML()
typically returns a result similar to the following, as a CLOB value:


18-22 Oracle XML DB Developer's Guide

Generating XML using DBMS_XMLGEN



100
Steven
King
SKING
515.123.4567
17-JUN-87
AD_PRES
24000
90


101
Neena
Kochhar
NKOCHHAR
515.123.4568
21-SEP-89
AD_VP
17000
100
90



The default mapping between relational data and XML data is as follows:
■

■

Each row returned by the SQL query maps to an XML element with the default
element name ROW.
Each column returned by the SQL query maps to a child element of the ROW
element.

■

The entire result is wrapped in a ROWSET element.

■

Binary data is transformed to its hexadecimal representation.

Element names ROW and ROWSET can be replaced with names you choose, using
DBMS_XMLGEN procedures setRowTagName and setRowSetTagName, respectively.
The CLOB value returned by getXML has the same encoding as the database character
set. If the database character set is SHIFTJIS, then the XML document returned is also
SHIFTJIS.

Functions and Procedures of Package DBMS_XMLGEN
Table 18–1 describes the functions and procedures of package DBMS_XMLGEN.

Generating XML Data from the Database 18-23

Generating XML using DBMS_XMLGEN

Table 18–1

DBMS_XMLGEN Functions and Procedures

Function or Procedure

Description

SUBTYPE ctxHandle IS NUMBER

The context handle used by all functions.
Document Type Definition (DTD) or schema specifications:
NONE CONSTANT NUMBER:= 0;
DTD CONSTANT NUMBER:= 1;
SCHEMA CONSTANT NUMBER:= 2;
Can be used in function getXML to specify whether to generate
a DTD or XML schema or neither (NONE). Only the NONE
specification is supported.

newContext()

Given a query string, generate a new context handle to be used
in subsequent functions.

newContext(
queryString IN VARCHAR2)

Returns a new context
Parameter: queryString (IN)- the query string, the result of
which must be converted to XML
Returns: Context handle. Call this function first to obtain a
handle that you can use in the getXML and other functions to
get the XML back from the result.

newContext(
queryString IN SYS_REFCURSOR)
RETURN ctxHandle;

Creates a new context handle from a PL/SQL cursor variable.
The context handle can be used for the rest of the functions.

newContextFromHierarchy(
queryString IN VARCHAR2)
RETURN ctxHandle;

Parameter: queryString (IN) - the query string, the result of
which must be converted to XML. The query is a hierarchical
query typically formed using a CONNECT BY clause, and the
result must have the same property as the result set generated
by a CONNECT BY query. The result set must have only two
columns, the level number and an XML value. The level number
is used to determine the hierarchical position of the XML value
within the result XML document.
Returns: Context handle. Call this function first to obtain a
handle that you can use in the getXML and other functions to
get a hierarchical XML with recursive elements back from the
result.

setRowTag()

Sets the name of the element separating all the rows. The default
name is ROW.

setRowTag(ctx IN ctxHandle,
rowTag IN VARCHAR2);

Parameters:
ctx(IN) - the context handle obtained from the newContext
call.
rowTag(IN) - the name of the ROW element. A NULL value for
rowTag indicates that you do not want the ROW element to be
present.
Call this procedure to set the name of the ROW element, if you do
not want the default ROW name to show up. You can also set
rowTag to NULL to suppress the ROW element itself.
However, since getXML returns complete XML documents, not
XML fragments, there must be a (single) root element. Therefore,
an error is raised if both the rowTag value and the rowSetTag
value (see setRowSetTag, next) are NULL and there is more
than one column or row in the output.

setRowSetTag()

18-24 Oracle XML DB Developer's Guide

Sets the name of the document root element. The default name is
ROWSET

Generating XML using DBMS_XMLGEN

Table 18–1 (Cont.) DBMS_XMLGEN Functions and Procedures
Function or Procedure

Description

setRowSetTag(ctx IN ctxHandle,
rowSetTag IN VARCHAR2);

Parameters:
ctx(IN) – the context handle obtained from the newContext
call.
rowSetTag(IN) – the name of the document root element to be
used in the output. A NULL value for rowSetTag indicates that
you do not want the ROWSET element to be present.
Call this procedure to set the name of the document root
element, if you do not want the default name ROWSET to be
used. You can set rowSetTag to NULL to suppress printing of
the document root element.
However, since function getXML returns complete XML
documents, not XML fragments, there must be a (single) root
element. Therefore, an error is raised if both the rowTag value
and the rowSetTag value (see setRowTag, previous) are NULL
and there is more than one column or row in the output, or if the
rowSetTag value is NULL and there is more than one row in the
output.

getXML()

Gets the XML document by fetching the maximum number of
rows specified. It appends the XML document to the CLOB
passed in.

getXML(ctx IN ctxHandle,
clobval IN OUT NCOPY clob,
dtdOrSchema IN number:= NONE);

Parameters:
ctx(IN) - The context handle obtained from calling
newContext.
clobval(IN/OUT) - the CLOB to which the XML document is
to be appended,
dtdOrSchema(IN) - whether you should generate the DTD or
Schema. This parameter is NOT supported.
Use this version of the getXML function, to avoid any extra
CLOB copies and if you want to reuse the same CLOB for
subsequent calls. This getXML call is more efficient than the next
flavor, though this involves that you create the LOB locator.
When generating the XML, the number of rows indicated by the
setSkipRows call are skipped, then the maximum number of
rows as specified by the setMaxRows call (or the entire result if
not specified) is fetched and converted to XML. Use the
getNumRowsProcessed function to check if any rows were
retrieved or not.

getXML()

Generates the XML document and returns it as a CLOB.

getXML(ctx IN ctxHandle,
dtdOrSchema IN number:= NONE)
RETURN clob;

Parameters:
ctx(IN) - The context handle obtained from calling
newContext.
dtdOrSchema(IN) - whether to generate a DTD or XML
schema. This parameter is not supported.
Returns: A temporary CLOB containing the document. Free the
temporary CLOB obtained from this function using the DBMS_
LOB.freeTemporary call.

Generating XML Data from the Database 18-25

Generating XML using DBMS_XMLGEN

Table 18–1 (Cont.) DBMS_XMLGEN Functions and Procedures
Function or Procedure

Description

getXMLType(
ctx IN ctxHandle,
dtdOrSchema IN number:= NONE)
RETURN XMLType;

Parameters:
ctx(IN) - The context handle obtained from calling
newContext.
dtdOrSchema(IN) - whether to generate a DTD or XML
schema. This parameter is not supported.
Returns: An XMLType instance containing the document.

getXML(
sqlQuery IN VARCHAR2,
dtdOrSchema IN NUMBER := NONE)
RETURN CLOB;

Converts the query results from the passed in SQL query string
to XML format, and returns the XML as a CLOB.

getXMLType(
sqlQuery IN VARCHAR2,
dtdOrSchema IN NUMBER := NONE)
RETURN XMLType;

Converts the query results from the passed in SQL query string
to XML format, and returns the XML as a CLOB.

getNumRowsProcessed()

Gets the number of SQL rows processed when generating XML
data using function getXML. This count does not include the
number of rows skipped before generating XML data.

getNumRowsProcessed(ctx IN ctxHandle)
RETURN number;

Parameter: queryString(IN)- the query string, the result of
which must be converted to XML
Returns: The number of SQL rows that were processed in the last
call to getXML.
You can call this to find out if the end of the result set has been
reached. This does not include the number of rows skipped before
generating XML data. Use this function to determine the
terminating condition if you are calling getXML in a loop. Note
that getXML would always generate an XML document even if
there are no rows present.

setMaxRows()

Sets the maximum number of rows to fetch from the SQL query
result for every invocation of the getXML call. It is an error to
call this function on a context handle created by function
newContextFromHierarchy.

setMaxRows(ctx IN ctxHandle,
maxRows IN NUMBER);

Parameters:
ctx(IN) - the context handle corresponding to the query
executed,
maxRows(IN) - the maximum number of rows to get for each
call to getXML.
The maxRows parameter can be used when generating
paginated results using this utility. For instance when generating
a page of XML or HTML data, you can restrict the number of
rows converted to XML and then in subsequent calls, you can
get the next set of rows and so on. This also can provide for
faster response times. It is an error to call this procedure on a
context handle created by function
newContextFromHierarchy.

setSkipRows()

18-26 Oracle XML DB Developer's Guide

Skips a given number of rows before generating the XML output
for every call to getXML. It is an error to call this function on a
context handle created by function
newContextFromHierarchy.

Generating XML using DBMS_XMLGEN

Table 18–1 (Cont.) DBMS_XMLGEN Functions and Procedures
Function or Procedure

Description

setSkipRows(ctx IN ctxHandle,
skipRows IN NUMBER);

Parameters:
ctx(IN) - the context handle corresponding to the query
executed,
skipRows(IN) - the number of rows to skip for each call to
getXML.
The skipRows parameter can be used when generating
paginated results for stateless Web pages using this utility. For
instance when generating the first page of XML or HTML data,
you can set skipRows to zero. For the next set, you can set the
skipRows to the number of rows that you got in the first case. It
is an error to call this function on a context handle created by
function newContextFromHierarchy.

setConvertSpecialChars()

Determines whether or not special characters in the XML data
must be converted into their escaped XML equivalent. For
example, the < sign is converted to <. The default behavior is
to perform escape conversions.

setConvertSpecialChars(
ctx IN ctxHandle,
conv IN BOOLEAN);

Parameters:
ctx(IN) - the context handle to use,
conv(IN) - true indicates that conversion is needed.
You can use this function to speed up the XML processing
whenever you are sure that the input data cannot contain any
special characters such as <, >, ", ', and so on, which must be
preceded by an escape character. It is expensive to scan the
character data to replace the special characters, particularly if it
involves a lot of data. So, in cases when the data is XML-safe,
this function can be called to improve performance.

useItemTagsForColl()

Sets the name of the collection elements. The default name for
collection elements it the type name itself. You can override that
to use the name of the column with the _ITEM tag appended to
it using this function.

useItemTagsForColl(ctx IN ctxHandle);

Parameter: ctx(IN) - the context handle.
If you have a collection of NUMBER, say, the default tag name for
the collection elements is NUMBER. You can override this action
and generate the collection column name with the _ITEM tag
appended to it, by calling this procedure.

restartQuery()

Restarts the query and generate the XML from the first row
again.

restartQuery(ctx IN ctxHandle);

Parameter: ctx(IN) - the context handle corresponding to the
current query. You can call this to start executing the query
again, without having to create a new context.

closeContext()

Closes a given context and releases all resources associated with
that context, including the SQL cursor and bind and define
buffers, and so on.

closeContext(ctx IN ctxHandle);

Parameter: ctx(IN) - the context handle to close. Closes all
resources associated with this handle. After this you cannot use
the handle for any other DBMS_XMLGEN function call.

Conversion Functions
convert(
xmlData IN varchar2,
flag IN NUMBER := ENTITY_ENCODE)
RETURN VARCHAR2;

Encodes or decodes the XML data string argument.
■

■

Encoding refers to replacing entity references such as < to
their escaped equivalent, such as <.
Decoding refers to the reverse conversion.

Generating XML Data from the Database 18-27

Generating XML using DBMS_XMLGEN

Table 18–1 (Cont.) DBMS_XMLGEN Functions and Procedures
Function or Procedure

Description

convert(
xmlData IN CLOB,
flag IN NUMBER := ENTITY_ENCODE)
RETURN CLOB;

Encodes or decodes the passed in XML CLOB data.
■

■

Encoding refers to replacing entity references such as < to
their escaped equivalent, such as <.
Decoding refers to the reverse conversion.

NULL Handling

The setNullHandling flag values are:

setNullHandling(ctx IN ctxHandle,
flag IN NUMBER);

■

DROP_NULLS CONSTANT NUMBER := 0;
This is the default setting and leaves out the tag for NULL
elements.

■

NULL_ATTR CONSTANT NUMBER := 1;
This sets xsi:nil = "true".

■

EMPTY_TAG CONSTANT NUMBER := 2;
This sets, for example, .

useNullAttributeIndicator(
ctx IN ctxHandle,
attrind IN BOOLEAN := TRUE);

useNullAttributeIndicator is a shortcut for
setNullHandling(ctx, NULL_ATTR).

setBindValue(
ctx IN ctxHandle,
bindVariableName IN VARCHAR2,
bindValue IN VARCHAR2);

Sets bind value for the bind variable appearing in the query
string associated with the context handle. The query string with
bind variables cannot be executed until all of the bind variables
are set values using setBindValue.

clearBindValue(ctx IN ctxHandle);

Clears all the bind values for all the bind variables appearing in
the query string associated with the context handle. Afterwards,
all of the bind variables must rebind new values using
setBindValue.

DBMS_XMLGEN Examples
Example 18–22 uses DBMS_XMLGEN to create an XML document by selecting employee
data from an object-relational table and putting the resulting CLOB value into a table.
Example 18–22 DBMS_XMLGEN: Generating Simple XML
CREATE TABLE temp_clob_tab (result CLOB);
DECLARE
qryCtx DBMS_XMLGEN.ctxHandle;
result CLOB;
BEGIN
qryCtx := DBMS_XMLGEN.newContext(
'SELECT * FROM hr.employees WHERE employee_id = 101');
-- Set the row header to be EMPLOYEE
DBMS_XMLGEN.setRowTag(qryCtx, 'EMPLOYEE');
-- Get the result
result := DBMS_XMLGEN.getXML(qryCtx);
INSERT INTO temp_clob_tab VALUES(result);
--Close context
DBMS_XMLGEN.closeContext(qryCtx);
END;
/

That generates the following XML document:
SELECT * FROM temp_clob_tab;

18-28 Oracle XML DB Developer's Guide

Generating XML using DBMS_XMLGEN

RESULT
------------------------------------------------------


101
Neena
Kochhar
NKOCHHAR
515.123.4568
21-SEP-05
AD_VP
17000
100
90


1 row selected.

Instead of generating all of the XML data for all rows, you can use the fetch interface
of package DBMS_XMLGEN to retrieve a fixed number of rows each time. This speeds
up response time and can help in scaling applications that need a Document Object
Model (DOM) Application Program Interface (API) on the resulting XML, particularly
if the number of rows is large.
Example 18–23 uses DBMS_XMLGEN to retrieve results from table HR.employees:
Example 18–23 DBMS_XMLGEN: Generating Simple XML with Pagination (Fetch)
-- Create a table to hold the results
CREATE TABLE temp_clob_tab (result clob);
DECLARE
qryCtx DBMS_XMLGEN.ctxHandle;
result CLOB;
BEGIN
-- Get the query context;
qryCtx := DBMS_XMLGEN.newContext('SELECT * FROM hr.employees');
-- Set the maximum number of rows to be 2
DBMS_XMLGEN.setMaxRows(qryCtx, 2);
LOOP
-- Get the result
result := DBMS_XMLGEN.getXML(qryCtx);
-- If no rows were processed, then quit
EXIT WHEN DBMS_XMLGEN.getNumRowsProcessed(qryCtx) = 0;
-- Do some processing with the lob data
-Insert the results into a table.
-You can print the lob out, output it to a stream,
-put it in a queue, or do any other processing.
INSERT INTO temp_clob_tab VALUES(result);
END LOOP;
--close context
DBMS_XMLGEN.closeContext(qryCtx);
END;
/
SELECT * FROM temp_clob_tab WHERE rownum < 3;

Generating XML Data from the Database 18-29

Generating XML using DBMS_XMLGEN

RESULT
---------------------------------------------------------


100
Steven
King
SKING
515.123.4567
17-JUN-03
AD_PRES
24000
90


101
Neena
Kochhar
NKOCHHAR
515.123.4568
21-SEP-05
AD_VP
17000
100
90





102
Lex
De Haan
LDEHAAN
515.123.4569
13-JAN-01
AD_VP
17000
100
90


103
Alexander
Hunold
AHUNOLD
590.423.4567
03-JAN-06
IT_PROG
9000
102
60


2 rows selected.

Example 18–24 uses DBMS_XMLGEN with object types to represent nested structures.

18-30 Oracle XML DB Developer's Guide

Generating XML using DBMS_XMLGEN

Example 18–24 DBMS_XMLGEN: Generating XML using Object Types
CREATE TABLE new_departments (department_id
NUMBER PRIMARY KEY,
department_name VARCHAR2(20));
CREATE TABLE new_employees (employee_id
NUMBER PRIMARY KEY,
last_name
VARCHAR2(20),
department_id
NUMBER REFERENCES new_departments);
CREATE TYPE emp_t AS OBJECT ("@employee_id"
NUMBER,
last_name
VARCHAR2(20));
/
INSERT INTO new_departments VALUES (10, 'SALES');
INSERT INTO new_departments VALUES (20, 'ACCOUNTING');
INSERT INTO new_employees
VALUES (30, 'Scott', 10);
INSERT INTO new_employees
VALUES (31, 'Mary', 10);
INSERT INTO new_employees
VALUES (40, 'John', 20);
INSERT INTO new_employees
VALUES (41, 'Jerry', 20);
COMMIT;
CREATE TYPE emplist_t AS TABLE OF emp_t;
/
CREATE TYPE dept_t AS OBJECT ("@department_id" NUMBER,
department_name VARCHAR2(20),
emplist
emplist_t);
/
CREATE TABLE temp_clob_tab (result CLOB);
DECLARE
qryCtx DBMS_XMLGEN.ctxHandle;
result CLOB;
BEGIN
DBMS_XMLGEN.setRowTag(qryCtx, NULL);
qryCtx := DBMS_XMLGEN.newContext
('SELECT dept_t(department_id,
department_name,
cast(MULTISET
(SELECT e.employee_id, e.last_name
FROM new_employees e
WHERE e.department_id = d.department_id)
AS emplist_t))
AS deptxml
FROM new_departments d');
-- now get the result
result := DBMS_XMLGEN.getXML(qryCtx);
INSERT INTO temp_clob_tab VALUES (result);
-- close context
DBMS_XMLGEN.closeContext(qryCtx);
END;
/
SELECT * FROM temp_clob_tab;

Here is the resulting XML:
RESULT
-------------------------------------------



SALES


Scott


Generating XML Data from the Database 18-31

Generating XML using DBMS_XMLGEN


Mary






ACCOUNTING


John


Jerry





1 row selected.

With relational data, the result is an XML document without nested elements. To
obtain nested XML structures, you can use object-relational data, where the mapping
is as follows:
■

■

Object types map as an XML element – see Chapter 7, "XML Schema Storage and
Query: Basic".
Attributes of the type map to sub-elements of the parent element
Complex structures can be obtained by using object types
and creating object views or object tables. A canonical mapping is
used to map object instances to XML.

Note:

When used in column names or attribute names, the at-sign (@) is
translated into an attribute of the enclosing XML element in the
mapping.
When you provide a user-defined data-type instance to DBMS_XMLGEN functions, the
user-defined data-type instance is mapped to an XML document using canonical
mapping: the attributes of the user-defined data type are mapped to XML elements.
Attributes with names starting with an at-sign character (@) are mapped to attributes
of the preceding element.
User-defined data-type instances can be used for nesting in the resulting XML
document.
For example, consider the tables emp and dept defined in Example 18–25. To generate
a hierarchical view of the data, that is, departments with their employees,
Example 18–25 defines suitable object types to create the structure inside the database.
Example 18–25 DBMS_XMLGEN: Generating XML using User-Defined Data-Type
Instances
CREATE TABLE dept (deptno NUMBER PRIMARY KEY, dname VARCHAR2(20));
CREATE TABLE emp (empno
NUMBER PRIMARY KEY, ename VARCHAR2(20),
deptno NUMBER REFERENCES dept);

18-32 Oracle XML DB Developer's Guide

Generating XML using DBMS_XMLGEN

-- empno is preceded by an at-sign (@) to indicate that it must
-- be mapped as an attribute of the enclosing Employee element.
CREATE TYPE emp_t AS OBJECT ("@empno" NUMBER, -- empno defined as attribute
ename
VARCHAR2(20));
/
INSERT INTO DEPT VALUES (10, 'Sports');
INSERT INTO DEPT VALUES(20, 'Accounting');
INSERT INTO EMP VALUES(200, 'John', 10);
INSERT INTO EMP VALUES(300, 'Jack', 10);
INSERT INTO EMP VALUES(400, 'Mary', 20);
INSERT INTO EMP VALUES(500, 'Jerry', 20);
COMMIT;
CREATE TYPE emplist_t AS TABLE OF emp_t;
/
CREATE TYPE dept_t AS OBJECT("@deptno" NUMBER,
dname
VARCHAR2(20),
emplist
emplist_t);
/
-- Department type dept_t contains a list of employees.
-- You can now query the employee and department tables and get
-- the result as an XML document, as follows:
CREATE TABLE temp_clob_tab (result CLOB);
DECLARE
qryCtx DBMS_XMLGEN.ctxHandle;
RESULT CLOB;
BEGIN
-- get query context
qryCtx := DBMS_XMLGEN.newContext(
'SELECT dept_t(deptno,
dname,
cast(MULTISET
(SELECT empno, ename FROM emp e WHERE e.deptno = d.deptno)
AS emplist_t))
AS deptxml
FROM dept d');
-- set maximum number of rows to 5
DBMS_XMLGEN.setMaxRows(qryCtx, 5);
-- set no row tag for this result, since there is a single ADT column
DBMS_XMLGEN.setRowTag(qryCtx, NULL);
LOOP
-- get result
result := DBMS_XMLGEN.getXML(qryCtx);
-- if there were no rows processed, then quit
EXIT WHEN DBMS_XMLGEN.getNumRowsProcessed(qryCtx) = 0;
-- do something with the result
INSERT INTO temp_clob_tab VALUES (result);
END LOOP;
END;
/

The MULTISET keyword for Oracle SQL function cast treats the employees working
in the department as a list, which cast assigns to the appropriate collection type. A
department instance is created using constructor dept_t, and DBMS_XMLGEN routines
create the XML data for the object instance.
SELECT * FROM temp_clob_tab;
RESULT
---------------------------------

Generating XML Data from the Database 18-33

Generating XML using DBMS_XMLGEN




Sports


John


Jack




Accounting


Mary


Jerry




1 row selected.

The default name ROW is not present because it was set to NULL. The deptno and
empno have become attributes of the enclosing element.
Example 18–26 uses DBMS_XMLGEN.getXMLType to generate a purchase order
document in XML format using object views.
Example 18–26 DBMS_XMLGEN: Generating an XML Purchase Order
-- Create relational schema and define object views
-- DBMS_XMLGEN maps user-defined data-type attribute names that start
-with an at-sign (@) to XML attributes
-- Purchase Order Object View Model
-- PhoneList varray object type
CREATE TYPE phonelist_vartyp AS VARRAY(10) OF VARCHAR2(20)
/
-- Address object type
CREATE TYPE address_typ AS OBJECT(Street VARCHAR2(200),
City
VARCHAR2(200),
State CHAR(2),
Zip
VARCHAR2(20))
/
-- Customer object type
CREATE TYPE customer_typ AS OBJECT(CustNo
NUMBER,
CustName VARCHAR2(200),
Address
address_typ,
PhoneList phonelist_vartyp)
/
-- StockItem object type
CREATE TYPE stockitem_typ AS OBJECT("@StockNo" NUMBER,
Price
NUMBER,
TaxRate
NUMBER)
18-34 Oracle XML DB Developer's Guide

Generating XML using DBMS_XMLGEN

/
-- LineItems object type
CREATE TYPE lineitem_typ AS OBJECT("@LineItemNo" NUMBER,
Item
stockitem_typ,
Quantity
NUMBER,
Discount
NUMBER)
/
-- LineItems ordered collection table
CREATE TYPE lineitems_ntabtyp AS TABLE OF lineitem_typ
/
-- Purchase Order object type
CREATE TYPE po_typ AUTHID CURRENT_USER
AS OBJECT(PONO
NUMBER,
Cust_ref
REF customer_typ,
OrderDate
DATE,
ShipDate
TIMESTAMP,
LineItems_ntab lineitems_ntabtyp,
ShipToAddr
address_typ)
/
-- Create Purchase Order relational model tables
-- Customer table
CREATE TABLE customer_tab (CustNo
NUMBER NOT NULL,
CustName
VARCHAR2(200),
Street
VARCHAR2(200),
City
VARCHAR2(200),
State
CHAR(2),
Zip
VARCHAR2(20),
Phone1
VARCHAR2(20),
Phone2
VARCHAR2(20),
Phone3
VARCHAR2(20),
CONSTRAINT cust_pk PRIMARY KEY (CustNo));
-- Purchase Order table
CREATE TABLE po_tab (PONo
NUMBER,
/* purchase order number */
Custno
NUMBER
/* foreign KEY referencing customer */
CONSTRAINT po_cust_fk REFERENCES customer_tab,
OrderDate DATE,
/* date of order */
ShipDate
TIMESTAMP,
/* date to be shipped */
ToStreet
VARCHAR2(200), /* shipto address */
ToCity
VARCHAR2(200),
ToState
CHAR(2),
ToZip
VARCHAR2(20),
CONSTRAINT po_pk PRIMARY KEY(PONo));
--Stock Table
CREATE TABLE stock_tab (StockNo NUMBER CONSTRAINT stock_uk UNIQUE,
Price
NUMBER,
TaxRate NUMBER);
--Line Items table
CREATE TABLE lineitems_tab (LineItemNo NUMBER,
PONo
NUMBER
CONSTRAINT li_po_fk REFERENCES po_tab,
StockNo
NUMBER,
Quantity
NUMBER,
Discount
NUMBER,
CONSTRAINT li_pk PRIMARY KEY (PONo, LineItemNo));
-- Create Object views
-- Customer Object View
CREATE OR REPLACE VIEW customer OF customer_typ
WITH OBJECT IDENTIFIER(CustNo)
AS SELECT c.custno, c.custname,
address_typ(c.street, c.city, c.state, c.zip),

Generating XML Data from the Database 18-35

Generating XML using DBMS_XMLGEN

phonelist_vartyp(phone1, phone2, phone3)
FROM customer_tab c;
--Purchase order view
CREATE OR REPLACE VIEW po OF po_typ
WITH OBJECT IDENTIFIER (PONo)
AS SELECT p.pono, make_ref(Customer, P.Custno), p.orderdate, p.shipdate,
cast(MULTISET
(SELECT lineitem_typ(l.lineitemno,
stockitem_typ(l.stockno, s.price,
s.taxrate),
l.quantity, l.discount)
FROM lineitems_tab l, stock_tab s
WHERE l.pono = p.pono AND s.stockno=l.stockno)
AS lineitems_ntabtyp),
address_typ(p.tostreet,p.tocity, p.tostate, p.tozip)
FROM po_tab p;
-- Create table with XMLType column to store purchase order in XML format
CREATE TABLE po_xml_tab (poid NUMBER, podoc XMLType)
/
-- Populate data
-------------------- Establish Inventory
INSERT INTO stock_tab VALUES(1004, 6750.00, 2);
INSERT INTO stock_tab VALUES(1011, 4500.23, 2);
INSERT INTO stock_tab VALUES(1534, 2234.00, 2);
INSERT INTO stock_tab VALUES(1535, 3456.23, 2);
-- Register Customers
INSERT INTO customer_tab
VALUES (1, 'Jean Nance', '2 Avocet Drive',
'Redwood Shores', 'CA', '95054',
'415-555-1212', NULL, NULL);
INSERT INTO customer_tab
VALUES (2, 'John Nike', '323 College Drive',
'Edison', 'NJ', '08820',
'609-555-1212', '201-555-1212', NULL);
-- Place orders
INSERT INTO po_tab
VALUES (1001, 1, '10-APR-1997', '10-MAY-1997',
NULL, NULL, NULL, NULL);
INSERT INTO po_tab
VALUES (2001, 2, '20-APR-1997', '20-MAY-1997',
'55 Madison Ave', 'Madison', 'WI', '53715');
-- Detail line items
INSERT INTO lineitems_tab VALUES(01, 1001, 1534, 12, 0);
INSERT INTO lineitems_tab VALUES(02, 1001, 1535, 10, 10);
INSERT INTO lineitems_tab VALUES(01, 2001, 1004, 1, 0);
INSERT INTO lineitems_tab VALUES(02, 2001, 1011, 2, 1);
-- Use package DBMS_XMLGEN to generate purchase order in XML format
-and store XMLType in table po_xml
DECLARE
qryCtx DBMS_XMLGEN.ctxHandle;
pxml XMLType;
cxml CLOB;
BEGIN
-- get query context;
qryCtx := DBMS_XMLGEN.newContext('SELECT pono,deref(cust_ref) customer,
p.orderdate,
p.shipdate,
lineitems_ntab lineitems,

18-36 Oracle XML DB Developer's Guide

Generating XML using DBMS_XMLGEN

shiptoaddr
FROM po p');
-- set maximum number of rows to be 1,
DBMS_XMLGEN.setMaxRows(qryCtx, 1);
-- set ROWSET tag to NULL and ROW tag to PurchaseOrder
DBMS_XMLGEN.setRowSetTag(qryCtx, NULL);
DBMS_XMLGEN.setRowTag(qryCtx, 'PurchaseOrder');
LOOP
-- get purchase order in XML format
pxml := DBMS_XMLGEN.getXMLType(qryCtx);
-- if there were no rows processed, then quit
EXIT WHEN DBMS_XMLGEN.getNumRowsProcessed(qryCtx) = 0;
-- Store XMLType po in po_xml table (get the pono out)
INSERT INTO po_xml_tab(poid, poDoc)
VALUES(XMLCast(XMLQuery('//PONO/text()' PASSING pxml RETURNING CONTENT)
AS NUMBER),
pxml);
END LOOP;
END;
/

This query then produces two XML purchase-order documents:
SELECT XMLSerialize(DOCUMENT x.podoc AS CLOB) xpo FROM po_xml_tab x;
XPO
--------------------------------------------------
1001

1
Jean Nance

2 Avocet Drive
Redwood Shores
CA
95054


415-555-1212


10-APR-97
10-MAY-97 12.00.00.000000 AM



2234
2

12
0



3456.23
2

10
10

Generating XML Data from the Database 18-37

Generating XML using DBMS_XMLGEN





2001

2
John Nike

323 College Drive
Edison
NJ
08820


609-555-1212
201-555-1212


20-APR-97
20-MAY-97 12.00.00.000000 AM



6750
2

1
0



4500.23
2

2
1



55 Madison Ave
Madison
WI
53715


2 rows selected.

Example 18–27 shows how to open a cursor variable for a query and use that cursor
variable to create a new context handle for DBMS_XMLGEN.
Example 18–27 DBMS_XMLGEN: Generating a New Context Handle from a REF Cursor
CREATE TABLE emp_tab (emp_id
NUMBER PRIMARY KEY,
name
VARCHAR2(20),
dept_id
NUMBER);
Table created.
INSERT INTO emp_tab VALUES (122, 'Scott', 301);

18-38 Oracle XML DB Developer's Guide

Generating XML using DBMS_XMLGEN

1 row created.
INSERT INTO emp_tab
1 row created.
INSERT INTO emp_tab
1 row created.
INSERT INTO emp_tab
1 row created.
INSERT INTO emp_tab
1 row created.
COMMIT;

VALUES (123, 'Mary',

472);

VALUES (124, 'John',

93);

VALUES (125, 'Howard', 488);
VALUES (126, 'Sue',

16);

DECLARE
ctx
NUMBER;
maxrow NUMBER;
xmldoc CLOB;
refcur SYS_REFCURSOR;
BEGIN
DBMS_LOB.createtemporary(xmldoc, TRUE);
maxrow := 3;
OPEN refcur FOR 'SELECT * FROM emp_tab WHERE ROWNUM <= :1' USING maxrow;
ctx := DBMS_XMLGEN.newContext(refcur);
-- xmldoc will have 3 rows
DBMS_XMLGEN.getXML(ctx, xmldoc, DBMS_XMLGEN.NONE);
DBMS_OUTPUT.put_line(xmldoc);
DBMS_LOB.freetemporary(xmldoc);
CLOSE refcur;
DBMS_XMLGEN.closeContext(ctx);
END;
/



122
Scott
301


123
Mary
472


124
John
93


PL/SQL procedure successfully completed.

Oracle Database PL/SQL Language Reference for more
information about cursor variables (REF CURSOR)

See Also:

Example 18–28 shows how to specify NULL handling when using DBMS_XMLGEN.
Example 18–28 DBMS_XMLGEN: Specifying NULL Handling
CREATE TABLE emp_tab (emp_id
name
dept_id

NUMBER PRIMARY KEY,
VARCHAR2(20),
NUMBER);

Generating XML Data from the Database 18-39

Generating XML using DBMS_XMLGEN

Table created.
INSERT INTO emp_tab VALUES
1 row created.
INSERT INTO emp_tab VALUES
1 row created.
INSERT INTO emp_tab VALUES
1 row created.
COMMIT;
CREATE TABLE temp_clob_tab
Table created.

(30, 'Scott', NULL);
(31, 'Mary', NULL);
(40, 'John', NULL);

(result CLOB);

DECLARE
qryCtx DBMS_XMLGEN.ctxHandle;
result CLOB;
BEGIN
qryCtx := DBMS_XMLGEN.newContext('SELECT * FROM emp_tab where name = :NAME');
-- Set the row header to be EMPLOYEE
DBMS_XMLGEN.setRowTag(qryCtx, 'EMPLOYEE');
-- Drop nulls
DBMS_XMLGEN.setBindValue(qryCtx, 'NAME', 'Scott');
DBMS_XMLGEN.setNullHandling(qryCtx, DBMS_XMLGEN.DROP_NULLS);
result := DBMS_XMLGEN.getXML(qryCtx);
INSERT INTO temp_clob_tab VALUES(result);
-- Null attribute
DBMS_XMLGEN.setBindValue(qryCtx, 'NAME', 'Mary');
DBMS_XMLGEN.setNullHandling(qryCtx, DBMS_XMLGEN.NULL_ATTR);
result := DBMS_XMLGEN.getXML(qryCtx);
INSERT INTO temp_clob_tab VALUES(result);
-- Empty tag
DBMS_XMLGEN.setBindValue(qryCtx, 'NAME', 'John');
DBMS_XMLGEN.setNullHandling(qryCtx, DBMS_XMLGEN.EMPTY_TAG);
result := DBMS_XMLGEN.getXML(qryCtx);
INSERT INTO temp_clob_tab VALUES(result);
--Close context
DBMS_XMLGEN.closeContext(qryCtx);
END;
/
PL/SQL procedure successfully completed.
SELECT * FROM temp_clob_tab;
RESULT
------------------------------------------


30
Scott





31
Mary




18-40 Oracle XML DB Developer's Guide

Generating XML using DBMS_XMLGEN




40
John



3 rows selected.

Function DBMS_XMLGEN.newContextFromHierarchy takes as argument a
hierarchical query string, which is typically formulated with a CONNECT BY clause. It
returns a context that can be used to generate a hierarchical XML document with
recursive elements.
The hierarchical query returns two columns, the level number (a pseudocolumn
generated by CONNECT BY query) and an XMLType. The level is used to determine the
position of the XMLType value within the hierarchy of the result XML document.
It is an error to set the skip number of rows or the maximum number of rows for a
context created using newContextFromHierarchy.
Example 18–29 uses DBMS_ XMLGEN.newContextFromHierarchy to generate a
manager–employee hierarchy.
Example 18–29 DBMS_XMLGEN: Generating Recursive XML with a Hierarchical Query
CREATE TABLE sqlx_display (id NUMBER, xmldoc XMLType);
Table created.
DECLARE
qryctx DBMS_XMLGEN.ctxhandle;
result XMLType;
BEGIN
qryctx :=
DBMS_XMLGEN.newContextFromHierarchy(
'SELECT level,
XMLElement("employees",
XMLElement("enumber", employee_id),
XMLElement("name", last_name),
XMLElement("Salary", salary),
XMLElement("Hiredate", hire_date))
FROM hr.employees
START WITH last_name=''De Haan'' CONNECT BY PRIOR employee_id=manager_id
ORDER SIBLINGS BY hire_date');
result := DBMS_XMLGEN.getxmltype(qryctx);
DBMS_OUTPUT.put_line('');
DBMS_OUTPUT.put_line(to_char(DBMS_XMLGEN.getNumRowsProcessed(qryctx)));
DBMS_OUTPUT.put_line('');
INSERT INTO sqlx_display VALUES (2, result);
COMMIT;
DBMS_XMLGEN.closecontext(qryctx);
END;
/

6

PL/SQL procedure successfully completed.

Generating XML Data from the Database 18-41

Generating XML using DBMS_XMLGEN

SELECT xmldoc FROM sqlx_display WHERE id = 2;
XMLDOC
----------------------------------------------------

102
De Haan
17000
2001-01-13

103
Hunold
9000
2006-01-03

105
Austin
4800
2005-06-25


106
Pataballa
4800
2006-02-05


107
Lorentz
4200
2007-02-07


104
Ernst
6000
2007-05-21



1 row selected.

By default, the ROWSET tag is NULL: there is no default ROWSET tag used to enclose the
XML result. However, you can explicitly set the ROWSET tag by using procedure
setRowSetTag, as follows:
CREATE TABLE gg (x XMLType);
Table created.
DECLARE
qryctx DBMS_XMLGEN.ctxhandle;
result CLOB;
BEGIN
qryctx := DBMS_XMLGEN.newContextFromHierarchy(
'SELECT level,
XMLElement("NAME", last_name) AS myname FROM hr.employees
CONNECT BY PRIOR employee_id=manager_id
START WITH employee_id = 102');

18-42 Oracle XML DB Developer's Guide

Generating XML using DBMS_XMLGEN

DBMS_XMLGEN.setRowSetTag(qryctx, 'mynum_hierarchy');
result:=DBMS_XMLGEN.getxml(qryctx);
DBMS_OUTPUT.put_line('');
DBMS_OUTPUT.put_line(to_char(DBMS_XMLGEN.getNumRowsProcessed(qryctx)));
DBMS_OUTPUT.put_line('');
INSERT INTO gg VALUES(XMLType(result));
COMMIT;
DBMS_XMLGEN.closecontext(qryctx);
END;
/

6

PL/SQL procedure successfully completed.
SELECT * FROM gg;
X
---------------------------------------------------------

De Haan
Hunold
Ernst
Austin
Pataballa
Lorentz



1 row selected.

If the query string used to create a context contains host variables, you can use
PL/SQL method setBindValue() to give the variables values before query
execution. Example 18–30 illustrates this.
Example 18–30 DBMS_XMLGEN: Binding Query Variables using SETBINDVALUE()
-- Bind one variable
DECLARE
ctx NUMBER;
xmldoc CLOB;
BEGIN
ctx := DBMS_XMLGEN.newContext(
'SELECT * FROM employees WHERE employee_id = :NO');
DBMS_XMLGEN.setBindValue(ctx, 'NO', '145');
xmldoc := DBMS_XMLGEN.getXML(ctx);
DBMS_OUTPUT.put_line(xmldoc);
DBMS_XMLGEN.closeContext(ctx);
EXCEPTION
WHEN OTHERS THEN DBMS_XMLGEN.closeContext(ctx);
RAISE;
END;
/



145
John

Generating XML Data from the Database 18-43

Generating XML using DBMS_XMLGEN

Russell
JRUSSEL
011.44.1344.429268
01-OCT-04
SA_MAN
14000
.4
100
80


PL/SQL procedure successfully completed.
-- Bind one variable twice with different values
DECLARE
ctx NUMBER;
xmldoc CLOB;
BEGIN
ctx := DBMS_XMLGEN.newContext('SELECT * FROM employees
WHERE hire_date = :MDATE');
DBMS_XMLGEN.setBindValue(ctx, 'MDATE', '01-OCT-04');
xmldoc := DBMS_XMLGEN.getXML(ctx);
DBMS_OUTPUT.put_line(xmldoc);
DBMS_XMLGEN.setBindValue(ctx, 'MDATE', '10-MAR-05');
xmldoc := DBMS_XMLGEN.getXML(ctx);
DBMS_OUTPUT.put_line(xmldoc);
DBMS_XMLGEN.closeContext(ctx);
EXCEPTION
WHEN OTHERS THEN DBMS_XMLGEN.closeContext(ctx);
RAISE;
END;
/



145
John
Russell
JRUSSEL
011.44.1344.429268
01-OCT-04
SA_MAN
14000
.4
100
80





147
Alberto
Errazuriz
AERRAZUR
011.44.1344.429278
10-MAR-05
SA_MAN

18-44 Oracle XML DB Developer's Guide

Generating XML using DBMS_XMLGEN

12000
.3
100
80


159
Lindsey
Smith
LSMITH
011.44.1345.729268
10-MAR-97
SA_REP
8000
.3
146
80


PL/SQL procedure successfully completed.
-- Bind two variables
DECLARE
ctx NUMBER;
xmldoc CLOB;
BEGIN
ctx := DBMS_XMLGEN.newContext('SELECT * FROM employees
WHERE employee_id = :NO
AND hire_date = :MDATE');
DBMS_XMLGEN.setBindValue(ctx, 'NO', '145');
DBMS_XMLGEN.setBindValue(ctx, 'MDATE', '01-OCT-04');
xmldoc := DBMS_XMLGEN.getXML(ctx);
DBMS_OUTPUT.put_line(xmldoc);
DBMS_XMLGEN.closeContext(ctx);
EXCEPTION
WHEN OTHERS THEN DBMS_XMLGEN.closeContext(ctx);
RAISE;
END;
/



145
John
Russell
JRUSSEL
011.44.1344.429268
01-OCT-04
SA_MAN
14000
.4
100
80


PL/SQL procedure successfully completed.

Generating XML Data from the Database 18-45

SYS_XMLGEN Oracle SQL Function

SYS_XMLGEN Oracle SQL Function
Oracle SQL function sys_XMLGen is similar to standard SQL/XML function
XMLElement, but it takes a single argument and it converts the result to an XMLType
instance. Unlike the other XML generation functions, sys_XMLGen always returns a
well-formed XML document. Unlike package DBMS_XMLGEN, which operates at a query
level, sys_XMLGen operates at the row level, returning an XML document for each row.
Example 18–31 uses sys_XMLGen to query XML instances, returning an XML
document for each row of relational data.
Example 18–31 Creating XML Data using SYS_XMLGEN
SELECT sys_XMLGen(employee_id) AS "result"
FROM employees WHERE first_name LIKE 'John%';

The resulting XML documents are as follows:
result
--------------
110

139

145
3 rows selected.

SYS_XMLGEN Syntax
Oracle SQL function sys_XMLGen takes as argument a scalar value, object type, or
XMLType instance to be converted to an XML document. It also takes an optional
XMLFormat object (previously called XMLGenFormatType), which you can use to
specify formatting options for the resulting XML document. The syntax is shown in
Figure 18–14.
Figure 18–14

SYS_XMLGEN Syntax
,

SYS_XMLGEN

(

expr

fmt
)

Expression expr evaluates to a particular row and column of the database. It can be a
scalar value, a user-defined data-type instance, or an XMLType instance.
■

■

■

If expr evaluates to a scalar value, then the function returns an XML element
containing the scalar value.
If expr evaluates to a user-defined data-type instance, then the function maps the
user-defined data-type attributes to XML elements.
If expr evaluates to an XMLType instance, then the function encloses the
document in an XML element whose default tag name is ROW.

By default, the elements of the XML document match expr. For example, if expr
resolves to a column name, then the enclosing XML element has the same name as the
column. If you want to format the XML document differently, then specify fmt, which
is an instance of the XMLFormat object.

18-46 Oracle XML DB Developer's Guide

SYS_XMLGEN Oracle SQL Function

You can use a WHERE clause in a query to suppress  tags with sys_XMLGen, if
you do not want NULL values represented:
SELECT sys_XMLGen(x) FROM table_name WHERE x IS NOT NULL;

Example 18–32 retrieves the employee first name from table HR.employees, where
the employee_id value is 110, and it generates an XMLType instance containing an
XML document with an FIRST_NAME element.
Example 18–32 SYS_XMLGEN: Generating an XML Element from a Database Column
SELECT XMLSerialize(DOCUMENT SYS_XMLGEN(first_name))
FROM employees WHERE employee_id = 110;
XMLSERIALIZE(DOCUMENTSYS_XMLGEN(FIRST_NAME))
-------------------------------------------
John
1 row selected.

Advantages of using Oracle SQL Function SYS_XMLGEN
Oracle SQL function sys_XMLGen has the following advantages:
■
■

You can create and query XML instances within SQL queries.
Using the object-relational infrastructure, you can create complex and nested XML
instances from simple relational tables. For example, when you use an XMLType
view that uses sys_XMLGen on top of an object type, Oracle XML DB rewrites
these queries when possible. See also Chapter 8, "XPath Rewrite for Structured
Storage".

sys_XMLGen creates an XML document from a user-defined data-type instance, a
scalar value, or an XMLType instance. It returns an XMLType instance.
sys_XMLGen also accepts an optional XMLFormat object as argument, which you can
use to customize the result. A NULL format object implies that the default mapping
action is to be used.

Using XMLFormat Object Type
You can use the XMLFormat object to specify formatting arguments for Oracle SQL
functions sys_XMLGen and sys_XMLAgg.
Function sys_XMLGen returns an XMLType instance containing an XML document.
Oracle Database provides the XMLFormat object to format the output of sys_XMLGen.
Table 18–2 lists the attributes of object XMLFormat.

Generating XML Data from the Database 18-47

SYS_XMLGEN Oracle SQL Function

Table 18–2

Attributes of the XMLFormat Object

Attribute

Data Type

Purpose

enclTag

VARCHAR2(100)

The name of the enclosing tag for the result of the sys_XMLGen
function. If the input to the function is a column name, then the
column name is used as the default value. Otherwise, the default
value is ROWSET. When schemaType is set to USE_GIVEN_
SCHEMA, this attribute also provides the name of the XML schema
element.

schemaType

VARCHAR2(100)

The type of schema generation for the output document. Valid
values are 'NO_SCHEMA' and 'USE_GIVEN_SCHEMA'. The default
value is 'NO_SCHEMA'.

schemaName

VARCHAR2(4000)

The name of the target schema used if schemaType is 'USE_
GIVEN_SCHEMA'. If you specify schemaName, then the enclosing
tag is used as the element name.

targetNameSpace

VARCHAR2(4000)

The target namespace if the schema is specified (that is,
schemaType is GEN_SCHEMA_*, or USE_GIVEN_SCHEMA)

dburl

VARCHAR2(2000)

The URL to the database to be used if WITH_SCHEMA is specified.
If this attribute is not specified, then a relative URL reference is
used for the URL to the types.

processingIns

VARCHAR2(4000)

User-provided processing instructions. They are appended to the
top of the function output, before the element.

You can use PL/SQL method createFormat() to implement the XMLFormat object.
Method createFormat() of object XMLFormat accepts as arguments the enclosing
element name, the XML schema type, and the XML schema name. Default values are
provided for the other XMLFormat attributes.
See Also:
■

■

Example 18–35 for an example of using createFormat to name
the root element that is output by sys_XMLGen
Oracle Database SQL Language Reference for more information about
sys_XMLGen and the XMLFormat object

Oracle SQL function sys_XMLGen converts a scalar value to an element that contains
the scalar value. The query in Example 18–33 illustrates this. It returns an XML
document that contains the employee_id value as the content of element
EMPLOYEE_ID.
Example 18–33 SYS_XMLGEN: Converting a Scalar Value to XML Element Contents
SELECT sys_XMLGen(employee_id) FROM hr.employees WHERE ROWNUM < 2;
SYS_XMLGEN(EMPLOYEE_ID)
--------------------------
100
1 row selected.

The enclosing element name, in this case EMPLOYEE_ID, is derived from the column
name passed to sys_XMLGen. The query result is a single row containing an XMLType
instance that corresponds to a complete XML document.

18-48 Oracle XML DB Developer's Guide

SYS_XMLGEN Oracle SQL Function

In Example 18–33, the column name EMPLOYEE_ID is used by default for the XML
element name. If the column name cannot be derived directly, then the default name
ROW is used instead, as shown in Example 18–34.
Example 18–34 SYS_XMLGEN: Default Element Name ROW
SELECT sys_XMLGen(employee_id*2) FROM hr.employees WHERE ROWNUM < 2;
SYS_XMLGEN(EMPLOYEE_ID*2)
------------------------
200
1 row selected.

In Example 18–34, the argument to sys_XMLGen is not a simple column name, so the
name of the output element tag cannot be a column name – the default element name,
ROW, is used.
You can override the default ROW tag by supplying an XMLFormat object as the second
sys_XMLGen argument. Example 18–35 illustrates this: the query passes a formatting
argument to sys_XMLGen, to name the element explicitly.
Example 18–35 Overriding the Default Element Name using SYS_XMLGEN with
XMLFormat
SELECT XMLSerialize(DOCUMENT
SYS_XMLGEN(employee_id*2,
XMLFormat.createformat('DOUBLE_ID'))
AS CLOB)
FROM hr.employees WHERE ROWNUM < 2;
XMLSERIALIZE(DOCUMENTSYS_XMLGEN(EMPLOYEE_ID*2,XMLFORMAT.CREATEFORMAT('DOUBLE_ID'
-------------------------------------------------------------------------------
200
1 row selected.

When you provide a user-defined data-type instance as an argument to sys_XMLGen,
the instance is canonically mapped to an XML document. In this mapping, the
user-defined data-type attributes are mapped to XML elements.
Any data-type attributes with names that start with an at sign (@) are mapped to
attributes of the preceding XML element. User-defined data-type instances can be used
to obtain nesting in the resulting XML document.
Example 18–36 shows how to generate hierarchical XML for the
employee-and-department example of section "Generating XML using DBMS_
XMLGEN" on page 18-21.
Example 18–36 SYS_XMLGEN: Converting a User-Defined Data-Type Instance to XML
CREATE OR REPLACE TYPE hr.emp_t AS OBJECT(empno
ename
job
mgr
hiredate
sal
comm
/

NUMBER(6),
VARCHAR2(25),
VARCHAR2(10),
NUMBER(6),
DATE,
NUMBER(8,2),
NUMBER(2,2));

Generating XML Data from the Database 18-49

SYS_XMLGEN Oracle SQL Function

Type created.
CREATE OR REPLACE TYPE hr.emplist_t AS TABLE OF emp_t;
/
Type created.
CREATE OR REPLACE TYPE hr.dept_t AS OBJECT(deptno NUMBER(4),
dname
VARCHAR2(30),
loc
VARCHAR2(4),
emplist emplist_t);
/
Type created.
SELECT XMLSerialize(
DOCUMENT
SYS_XMLGEN(
dept_t(department_id,
department_name,
d.location_id,
cast(MULTISET
(SELECT emp_t(e.employee_id, e.last_name,
e.job_id, e.manager_id, e.hire_date,
e.salary, e.commission_pct)
FROM hr.employees e
WHERE e.department_id = d.department_id)
AS emplist_t)))
AS CLOB)
AS deptxml
FROM hr.departments d WHERE department_id = 10 OR department_id = 20;

The MULTISET keyword for Oracle SQL function cast treats the employees working
in the department as a list, which cast assigns to the appropriate collection type.
sys_XMLGen creates the XML data for the object instance.
The result is as follows. The default name ROW is present because the function cannot
deduce the name of the input operand directly.
DEPTXML
------------------------------------

10
Administration
1700


200
Whalen
AD_ASST
101
17-SEP-03
4400





20
Marketing
1800



18-50 Oracle XML DB Developer's Guide

SYS_XMLGEN Oracle SQL Function

201
Hartstein
MK_MAN
100
17-FEB-04
13000


202
Fay
MK_REP
201
17-AUG-05
6000



2 rows selected.

The difference between using SQL function sys_XMLGen
and PL/SQL package DBMS_XMLGEN is apparent from the
preceding example. Function sys_XMLGen works inside SQL
queries, and operates on the expressions and columns within the
rows. Package DBMS_XMLGEN works on the entire result set.

Note:

If you pass an XML document to function sys_XMLGen, the function wraps the
document (or fragment) with an element whose tag name is the default ROW, or the
name passed in through the XMLFormat formatting object. This functionality can be
used to turn XML fragments into well-formed documents. Example 18–37 illustrates
this.
Example 18–37 SYS_XMLGEN: Converting an XMLType Instance
CREATE TABLE po_xml_tab (podoc XMLType);
Table created.
INSERT INTO po_xml_tab VALUES (XMLType('

John
200


Jack
400


Joseph
300

'));
1 row created.
COMMIT;

This query extracts ENAME elements:
SELECT XMLQuery('/DOCUMENT/EMPLOYEE/ENAME' PASSING e.podoc RETURNING CONTENT)
FROM po_xml_tab e;

Generating XML Data from the Database 18-51

SYS_XMLGEN Oracle SQL Function

The query result is an XML document fragment (pretty-printed here for clarity):
John
Jack
Joseph

You can make such a fragment into a valid XML document by calling sys_XMLGen to
wrap a root element around the fragment, as follows:
SELECT XMLSerialize(DOCUMENT
sys_XMLGen(XMLQuery('/DOCUMENT/EMPLOYEE/ENAME'
PASSING e.podoc RETURNING CONTENT))
AS CLOB)
FROM po_xml_tab e;

This places a ROW element around the fragment, as follows (pretty-printed here for
clarity):


John
Jack
Joseph


Note: If the input to sys_XMLGen is a column, then the column
name is used as the default element name. You can override the
element name using the XMLFormat formatting object as a second
argument to sys_XMLGen. See "Using XMLFormat Object Type" on
page 18-47.

Example 18–38 shows how to use sys_XMLGen with object views. (For any undefined
entities here, refer to the code in Example 18–26 on page 18-34.)
Example 18–38 Using SYS_XMLGEN with Object Views
-- Create purchase order object type
CREATE OR REPLACE TYPE po_typ AUTHID CURRENT_USER
AS OBJECT(pono
NUMBER,
customer
customer_typ,
orderdate
DATE,
shipdate
TIMESTAMP,
lineitems_ntab lineitems_ntabtyp,
shiptoaddr
address_typ)
/
--Purchase order view
CREATE OR REPLACE VIEW po OF po_typ
WITH OBJECT IDENTIFIER (PONO)
AS SELECT p.pono, customer_typ(p.custno, c.custname, c.address, c.phonelist),
p.orderdate, p.shipdate,
cast(MULTISET
(SELECT lineitem_typ(l.lineitemno,
stockitem_typ(l.stockno, s.price,
s.taxrate),
l.quantity, l.discount)
FROM lineitems_tab l, stock_tab s
WHERE l.pono = p.pono AND s.stockno=l.stockno)

18-52 Oracle XML DB Developer's Guide

SYS_XMLGEN Oracle SQL Function

AS lineitems_ntabtyp),
address_typ(p.tostreet, p.tocity, p.tostate, p.tozip)
FROM po_tab p, customer c
WHERE p.custno=c.custno;
-- Use sys_XMLGen to generate PO in XML format
SELECT XMLSerialize(DOCUMENT
SYS_XMLGEN(OBJECT_VALUE,
XMLFormat.createFormat('PurchaseOrder'))
AS CLOB) PO
FROM po p WHERE p.pono=1001;

The query returns the purchase order in XML format:
PO
---------------------------------------------

1001

1
Jean Nance

2 Avocet Drive
Redwood Shores
CA
95054


415-555-1212


10-APR-97
10-MAY-97 12.00.00.000000 AM



2234
2

12
0



3456.23
2

10
10




1 row selected.

Generating XML Data from the Database 18-53

SYS_XMLAGG Oracle SQL Function

SYS_XMLAGG Oracle SQL Function
Oracle SQL function sys_XMLAgg aggregates all XML documents or fragments
represented by an expression, producing a single XML document from them. It wraps
the results of the expression in a new element named ROWSET (by default).
Oracle function sys_XMLAgg is similar to standard SQL/XML function XMLAgg, but
sys_XMLAgg returns a single node and it accepts an XMLFormat parameter. You can
use that parameter to format the resulting XML document in various ways.
Figure 18–15

SYS_XMLAGG Syntax
,

SYS_XMLAGG

(

See Also:

fmt

expr

)

Oracle Database SQL Language Reference

Guidelines for Generating XML with Oracle XML DB
This section describes additional guidelines for generating XML using Oracle
XML DB.

Ordering Query Results Before Aggregating, using XMLAGG ORDER BY Clause
To use the XMLAgg ORDER BY clause before aggregation, specify the ORDER BY
clause following the first XMLAGG argument. This is illustrated in Example 18–39.
Example 18–39 Using XMLAGG ORDER BY Clause
CREATE TABLE dev_tab (dev
dev_total
devname
Table created.
INSERT INTO dev_tab VALUES (16,
1 row created.
INSERT INTO dev_tab VALUES (2,
1 row created.
INSERT INTO dev_tab VALUES (1,
1 row created.
INSERT INTO dev_tab VALUES (9,
1 row created.
COMMIT;

NUMBER,
NUMBER,
VARCHAR2(20));
5,

'Alexis');

14, 'Han');
2,

'Jess');

88, 'Kurt');

The result of the following query is aggregated according to the order of the dev
column. (The result is shown here pretty-printed, for clarity.)
SELECT XMLAgg(XMLElement("Dev",
XMLAttributes(dev AS "id", dev_total AS "total"),
devname)
ORDER BY dev)
FROM tab1 dev_total;
XMLAGG(XMLELEMENT("DEV",XMLATTRIBUTES(DEVAS"ID",DEV_TOTALAS"TOTAL"),DEVNAME)ORDE
-------------------------------------------------------------------------------Jess
Han
Kurt
Alexis

18-54 Oracle XML DB Developer's Guide

Guidelines for Generating XML with Oracle XML DB

1 row selected.

Returning a Rowset using XMLTABLE
You can use standard SQL/XML function XMLTable to return a rowset with relevant
portions of a document extracted as multiple rows, as shown in Example 18–40.
Example 18–40 Returning a Rowset using XMLTABLE
CONNECT oe
Enter password: password
Connected.
SELECT item.descr, item.partid
FROM purchaseorder,
XMLTable('$p/PurchaseOrder/LineItems/LineItem' PASSING OBJECT_VALUE
COLUMNS descr VARCHAR2(256) PATH 'Description',
partid VARCHAR2(14) PATH 'Part/@Id') item
WHERE item.partid = '715515012027'
OR item.partid = '715515011921'
ORDER BY partid;

This returns a rowset with just the descriptions and part IDs, ordered by part ID.
DESCR
-------------PARTID
-------------My Man Godfrey
715515011921
My Man Godfrey
715515011921
My Man Godfrey
715515011921
My Man Godfrey
715515011921
My Man Godfrey
715515011921
My Man Godfrey
715515011921
My Man Godfrey
715515011921
Mona Lisa
715515012027
Mona Lisa
715515012027
Mona Lisa
715515012027

Generating XML Data from the Database 18-55

Guidelines for Generating XML with Oracle XML DB

Mona Lisa
715515012027
Mona Lisa
715515012027
Mona Lisa
715515012027
Mona Lisa
715515012027
Mona Lisa
715515012027
Mona Lisa
715515012027
16 rows selected.

18-56 Oracle XML DB Developer's Guide

19
XMLType Views
This chapter describes how to create and use XMLType views. It contains these topics:
■

What Are XMLType Views?

■

Creating Non-Schema-Based XMLType Views

■

Creating XML Schema-Based XMLType Views

■

Creating XMLType Views from XMLType Tables

■

Referencing XMLType View Objects using SQL Function REF

■

DML (Data Manipulation Language) on XMLType Views

What Are XMLType Views?
XMLType views wrap existing relational and object-relational data in XML formats.
The major advantages of using XMLType views are:
■

■

You can exploit Oracle XML DB XML features that use XML schema functionality
without having to migrate your base legacy data.
With XMLType views, you can experiment with various other forms of storage,
besides the object-relational, CLOB, and binary XML storage available for XMLType
tables.

XMLType views are similar to object views. Each row of an XMLType view
corresponds to an XMLType instance. The object identifier for uniquely identifying
each row in the view can be created using SQL/XML functions XMLCast and
XMLQuery.
Throughout this chapter XML schema refers to the W3C XML Schema 1.0
recommendation, http://www.w3.org/XML/Schema.
There are two types of XMLType views:
■

■

Non-schema-based XMLType views. These views do not confirm to a particular
XML schema.
XML schema-based XMLType views. As with XMLType tables, XMLType views
that conform to a particular XML schema are called XML schema-based XMLType
views. These provide stronger typing than non-schema-based XMLType views.

XPath rewrite of queries over XMLType views is enabled for both XML schema-based
and non-schema-based XMLType views. XPath rewrite is described in Chapter 8,
"XPath Rewrite for Structured Storage".
To create an XML schema-based XMLType view, first register your XML schema. If the
view is an object view, that is, if it is constructed using an object type, then the XML
XMLType Views 19-1

Creating Non-Schema-Based XMLType Views

schema should have annotations that represent the bidirectional mapping from XML
to SQL object types. XMLType views conforming to this registered XML schema can
then be created by providing an underlying query that constructs instances of the
appropriate SQL object type.
See Also:
■

■

"Accessing XML Data in Oracle XML DB using Relational
Views" on page 3-48
Chapter 7, "XML Schema Storage and Query: Basic"

You can create XMLType views in any of the following ways:
■

■

■

Based on SQL/XML publishing functions, such as XMLElement, XMLForest,
XMLConcat, and XMLAgg. SQL/XML publishing functions can be used to
construct both non-schema-based XMLType views and XML schema-based
XMLType views. This enables construction of XMLType view from the underlying
relational tables directly without physically migrating those relational legacy data
into XML. However, to construct XML schema-based XMLType view, the XML
schema must be registered and the XML value generated by SQL/XML publishing
functions must be constrained to the XML schema.
Based on object types, object views, and Oracle SQL function sys_XMLGen.
Non-schema-based XMLType views can be constructed using object types, object
views, and function sys_XMLGen and XML schema-based XMLType view can be
constructed using object types and object views. This enables the construction of
the XMLType view from underlying relational or object relational tables directly
without physically migrating the relational or object relational legacy data into
XML. Creating non-schema-based XMLType view requires the use of sys_XMLGen
over existing object types or object views. Creating XML-schema-based XMLType
view requires to annotate the XML schema with a mapping to existing object types
or to generate the XML schema from the existing object types.
Directly from an XMLType table.

Creating XMLType Views: Syntax
Figure 19–1 shows the CREATE VIEW clause for creating XMLType views. See Oracle
Database SQL Language Reference for details on the CREATE VIEW syntax.
Figure 19–1 Creating XMLType Views Clause: Syntax
DEFAULT

XMLSchema_spec
OF

XMLTYPE

WITH

OBJECT

IDENTIFIER

,
(

expr

)

Creating Non-Schema-Based XMLType Views
Non-schema-based XMLType views are XMLType views whose resultant XML value is
not constrained to be a particular element in a registered XML schema. You can create
a non-schema-based XMLType view in either of these ways:
■

Using SQL/XML publishing functions.

19-2 Oracle XML DB Developer's Guide

Creating Non-Schema-Based XMLType Views

See Also: Chapter 18, "Generating XML Data from the Database",
for details on SQL/XML publishing functions
■

Using object types or object views, together with Oracle SQL function sys_
XMLGen. This is convenient when you already have object types, views, and tables
that you want to map to XML data.
See Also: "Creating XML Schema-Based XMLType Views using
Object Types or Object Views" on page 19-11

Creating Non-Schema-Based XMLType Views using SQL/XML Publishing Functions
Example 19–1 shows how to create an XMLType view using SQL/XML function
XMLELement.
Example 19–1

Creating an XMLType View using XMLELEMENT

CREATE OR REPLACE VIEW emp_view OF XMLType
WITH OBJECT ID (XMLCast(XMLQuery('/Emp/@empno'
PASSING OBJECT_VALUE RETURNING CONTENT)
AS BINARY_DOUBLE)) AS
SELECT XMLElement("Emp",
XMLAttributes(employee_id AS "empno"),
XMLForest(e.first_name ||' '|| e.last_name AS "name",
e.hire_date AS "hiredate"))
AS "result" FROM employees e WHERE salary > 15000;
SELECT * FROM emp_view;
SYS_NC_ROWINFO$
------------------------------------------------------------------------------------Steven King2003-06-17
Neena Kochhar2005-09-21
Lex De Haan2001-01-13

Existing data in relational tables or views can be exposed as XML this way. If a view is
generated using a SQL/XML publishing function, then queries that access that view
using XPath expressions can often be rewritten. These optimized queries can then
directly access the underlying relational columns. See Chapter 8, "XPath Rewrite for
Structured Storage" for details.
You can perform DML operations on these XMLType views, but, in general, you must
write instead-of triggers to handle the DML operation.

Creating Non-Schema-Based XMLType Views using Object Types and SYS_XMLGEN
You can also create an XMLType view using object types and Oracle SQL function
sys_XMLGen. Function sys_XMLGen accepts as argument an instance of an object
type, and it generates a corresponding instance of XMLType. The query in
Example 19–2 uses sys_XMLGen and produces the same result as the query of
Example 19–1.
Example 19–2

Creating an XMLType View using Object Types and SYS_XMLGEN

CREATE TYPE emp_t AS OBJECT ("@empno"
fname
lname
hiredate
/

NUMBER(6),
VARCHAR2(20),
VARCHAR2(25),
DATE);

XMLType Views 19-3

Creating XML Schema-Based XMLType Views

CREATE OR REPLACE VIEW employee_view OF XMLType
WITH OBJECT ID (XMLCast(XMLQuery('/Emp/@empno'
PASSING OBJECT_VALUE RETURNING CONTENT)
AS BINARY_DOUBLE)) AS
SELECT sys_XMLGen(emp_t(e.employee_id, e.first_name, e.last_name, e.hire_date),
XMLFormat('EMP'))
FROM employees e WHERE salary > 15000;
SELECT * FROM employee_view;
SYS_NC_ROWINFO$
-------------------------------------------------------
Steven
King
17-JUN-03



Neena
Kochhar
21-SEP-05



Lex
De Haan
13-JAN-01


Existing relational or object-relational data can be exposed as XML data using this
mechanism.

Creating XML Schema-Based XMLType Views
XML schema-based XMLType views are views whose data is constrained to conform to
an XML schema. You can create an XML schema-based XMLType view in either of
these ways:
■

Using SQL/XML publishing functions.
See Also: "Creating XML Schema-Based XMLType Views using
SQL/XML Publishing Functions" on page 19-4

■

Using object types or object views. This is convenient when you already have
object types, views, and tables that you want to map to XML data.
See Also: "Creating XML Schema-Based XMLType Views using
Object Types or Object Views" on page 19-11

Creating XML Schema-Based XMLType Views using SQL/XML Publishing Functions
You can use SQL/XML publishing functions to create XML schema-based XMLType
views in a similar way as for the non-schema-based case described in section "Creating
Non-Schema-Based XMLType Views":
19-4 Oracle XML DB Developer's Guide

Creating XML Schema-Based XMLType Views

1.

Create and register the XML schema document that contains the necessary XML
structures. You do not need to annotate the XML schema to define the mapping
between XML types and SQL object types.

2.

Use SQL/XML publishing functions to create an XMLType view that conforms to
the XML schema.

These two steps are illustrated in Example 19–3 and Example 19–4, respectively.
Example 19–3

Registering XML Schema emp_simple.xsd

BEGIN
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'http://www.oracle.com/emp_simple.xsd',
SCHEMADOC => '






















',
LOCAL
=> TRUE,
GENTYPES => TRUE);
END;

Example 19–3 assumes that you have an XML schema emp_simple.xsd that contains
XML structures defining an employee. It registers the XML schema with the target
location http://www.oracle.com/emp_simple.xsd.

XMLType Views 19-5

Creating XML Schema-Based XMLType Views

When using SQL/XML publishing functions to generate XML schema-based content,
you must specify the appropriate namespace information for all of the elements and
also indicate the location of the schema using attribute xsi:schemaLocation. These
can be specified using the XMLAttributes clause. Example 19–4 illustrates this.
Example 19–4

Creating an XMLType View using SQL/XML Publishing Functions

CREATE OR REPLACE VIEW emp_simple_xml OF XMLType
XMLSCHEMA "http://www.oracle.com/emp_simple.xsd" ELEMENT "Employee"
WITH OBJECT ID (XMLCast(XMLQuery('/Employee/EmployeeId/text()'
PASSING OBJECT_VALUE
RETURNING CONTENT)
AS BINARY_DOUBLE)) AS
SELECT
XMLElement("Employee",
XMLAttributes(
'http://www.oracle.com/emp_simple.xsd' AS "xmlns" ,
'http://www.w3.org/2001/XMLSchema-instance' AS "xmlns:xsi",
'http://www.oracle.com/emp_simple.xsd
http://www.oracle.com/emp_simple.xsd'
AS "xsi:schemaLocation"),
XMLForest(e.employee_id
AS "EmployeeId",
e.last_name
AS "Name",
e.job_id
AS "Job",
e.manager_id
AS "Manager",
e.hire_date
AS "HireDate",
e.salary
AS "Salary",
e.commission_pct AS "Commission",
XMLForest(
d.department_id
AS "DeptNo",
d.department_name AS "DeptName",
d.location_id
AS "Location") AS "Dept"))
FROM employees e, departments d
WHERE e.department_id = d.department_id;

In Example 19–4, function XMLElement creates XML element Employee. Function
XMLForest creates the children of element Employee. The XMLAttributes clause
inside XMLElement constructs the required XML namespace and schema location
attributes, so that the XML data that is generated conforms to the XML schema of the
view. The innermost call to XMLForest creates the children of element department,
which is a child of element Employee.
By default, the XML generation functions create a non-schema-based XML instance.
However, when the schema location is specified, using attribute
xsi:schemaLocation or xsi:noNamespaceSchemaLocation, Oracle XML DB
generates XML schema-based XML data. For XMLType views, as long as the names of
the elements and attributes match those in the XML schema, the XML data is
converted implicitly into a valid XML schema-based document. Any errors in the
generated XML data are caught later, when operations such as validation or extraction
operations are performed on the XML instance.
Example 19–5 queries the XMLType view, returning an XML result from tables
employees and departments. The result of the query is shown pretty-printed, for
clarity.
Example 19–5

Querying an XMLType View

SELECT OBJECT_VALUE AS RESULT FROM emp_simple_xml WHERE ROWNUM < 2;
RESULT
19-6 Oracle XML DB Developer's Guide

Creating XML Schema-Based XMLType Views

--------------------------------------------------------------------
200
Whalen
AD_ASST
101
2003-09-17
4400

10
Administration
1700



Using Namespaces with SQL/XML Publishing Functions
If you have complex XML schemas involving namespaces, you must use the partially
escaped mapping provided by the SQL/XML publishing functions and create
elements with appropriate namespaces and prefixes.
The query in Example 19–6 creates XML instances that have the correct namespace,
prefixes, and target schema location. It can be used as the query in the definition of
view emp_simple_xml.
Example 19–6

Using Namespace Prefixes with SQL/XML Publishing Functions

SELECT XMLElement("ipo:Employee",
XMLAttributes('http://www.oracle.com/emp_simple.xsd' AS "xmlns:ipo",
'http://www.oracle.com/emp_simple.xsd
http://www.oracle.com/emp_simple.xsd' AS "xmlns:xsi"),
XMLForest(e.employee_id
AS "ipo:EmployeeId",
e.last_name
AS "ipo:Name",
e.job_id
AS "ipo:Job",
e.manager_id
AS "ipo:Manager",
TO_CHAR(e.hire_date,'YYYY-MM-DD') AS "ipo:HireDate",
e.salary
AS "ipo:Salary",
e.commission_pct
AS "ipo:Commission",
XMLForest(d.department_id
AS "ipo:DeptNo",
d.department_name AS "ipo:DeptName", d.location_id
AS "ipo:Location") AS "ipo:Dept"))
FROM employees e, departments d
WHERE e.department_id = d.department_id AND d.department_id = 20;
BEGIN
-- Delete schema if it already exists (else error)
DBMS_XMLSCHEMA.deleteSchema('emp-noname.xsd', 4);
END;
XMLELEMENT("IPO:EMPLOYEE",XMLATTRIBUTES('HTTP://WWW.ORACLE.COM/EMP_SIMPLE.XSD'AS
-------------------------------------------------------------------------------
201Hartstein
MK_MAN100
2004-02-1713000
20Marketing
XMLType Views 19-7

Creating XML Schema-Based XMLType Views

1800
202
FayMK_REP201
2005-08-176000
20Marketing1800



If the XML schema had no target namespace, then you could use attribute
xsi:noNamespaceSchemaLocation to indicate that. Example 19–7 shows such an
XML schema.
Example 19–7

XML Schema with No Target Namespace

BEGIN
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'emp-noname.xsd',
SCHEMADOC => '






















',
LOCAL
=> TRUE,
GENTYPES => TRUE);
END;

Example 19–8 creates a view that conforms to the XML schema in Example 19–7. The
XMLAttributes clause creates an XML element that contains the noNamespace
schema location attribute.
Example 19–8

Creating a View for an XML Schema with No Target Namespace

CREATE OR REPLACE VIEW emp_xml OF XMLType
XMLSCHEMA "emp-noname.xsd" ELEMENT "Employee"
WITH OBJECT ID (XMLCast(XMLQuery('/Employee/EmployeeId/text()'
PASSING OBJECT_VALUE
RETURNING CONTENT)

19-8 Oracle XML DB Developer's Guide

Creating XML Schema-Based XMLType Views

AS BINARY_DOUBLE)) AS
SELECT XMLElement(
"Employee",
XMLAttributes('http://www.w3.org/2001/XMLSchema-instance' AS "xmlns:xsi",
'emp-noname.xsd' AS "xsi:noNamespaceSchemaLocation"),
XMLForest(e.employee_id
AS "EmployeeId",
e.last_name
AS "Name",
e.job_id
AS "Job",
e.manager_id
AS "Manager",
e.hire_date
AS "HireDate",
e.salary
AS "Salary",
e.commission_pct AS "Commission",
XMLForest(d.department_id
AS "DeptNo",
d.department_name AS "DeptName",
d.location_id
AS "Location") AS "Dept"))
FROM employees e, departments d
WHERE e.department_id = d.department_id;

Example 19–9 creates view dept_xml, which conforms to XML schema dept.xsd.
Example 19–9

Using SQL/XML Functions in XML Schema-Based XMLType Views

BEGIN
-- Delete schema if it already exists (else error)
DBMS_XMLSCHEMA.deleteSchema('http://www.oracle.com/dept.xsd', 4);
END;
/
BEGIN
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'http://www.oracle.com/dept.xsd',
SCHEMADOC => '






















',
LOCAL
=> TRUE,

XMLType Views 19-9

Creating XML Schema-Based XMLType Views

GENTYPES
END;

=> FALSE);

/
CREATE OR REPLACE VIEW dept_xml OF XMLType
XMLSCHEMA "http://www.oracle.com/dept.xsd" ELEMENT "Department"
WITH OBJECT ID (XMLCast(XMLQuery('/Department/DeptNo'
PASSING OBJECT_VALUE RETURNING CONTENT)
AS BINARY_DOUBLE)) AS
SELECT XMLElement(
"Department",
XMLAttributes(
'http://www.oracle.com/emp.xsd' AS "xmlns" ,
'http://www.w3.org/2001/XMLSchema-instance' AS "xmlns:xsi",
'http://www.oracle.com/dept.xsd
http://www.oracle.com/dept.xsd' AS "xsi:schemaLocation"),
XMLForest(d.department_id "DeptNo",
d.department_name "DeptName",
d.location_id "Location"),
(SELECT XMLagg(
XMLElement("Employee",
XMLForest(
e.employee_id "EmployeeId",
e.last_name "Name",
e.job_id "Job",
e.manager_id "Manager",
to_char(e.hire_date,'YYYY-MM-DD') "Hiredate",
e.salary "Salary",
e.commission_pct "Commission")))
FROM employees e
WHERE e.department_id = d.department_id))
FROM departments d;

This is the XMLType instance that results:
SELECT OBJECT_VALUE AS result FROM dept_xml WHERE ROWNUM < 2;
RESULT
---------------------------------------------------------------
10
Administration
1700

200
Whalen
AD_ASST
101
2003-09-17
4400



19-10 Oracle XML DB Developer's Guide

Creating XML Schema-Based XMLType Views

Creating XML Schema-Based XMLType Views using Object Types or Object Views
To create an XML schema-based XMLType view from object types or object views, do
the following:
1.

Create the object types, if they do not yet exist.

2.

Create and then register the XML schema, annotating it to define the mapping
between XML types and SQL object types and attributes.
You can annotate the XML schema before registering it. You typically do this when
you wrap existing data to create an XMLType view.
See:

Chapter 7, "XML Schema Storage and Query: Basic"

You can use PL/SQL functions DBMS_XMLSchema.generateSchema and DBMS_
XMLSchema.generateSchemas to generate the default XML mapping for
specified object types. The generated XML schema has the requisite annotations
SQLType, SQLSchema, and so on. When such an XML schema document is
registered, the following validation can occur:
■

■

3.

SQLType for attributes or elements based on simpleType. The SQL type
must be compatible with the XML type of the corresponding XMLType data.
For example, an XML string data type can be mapped only to a VARCHAR2
or a Large Object (LOB) data type.
SQLType specified for elements based on complexType. This is either a LOB
or an object type whose structure must be compatible with the declaration of
the complexType, that is, the object type must have the correct number of
attributes with the correct data types.

Create the XMLType view, specifying the XML schema URL and the root element
name. The query defining the view first constructs the object instances and then
converts them to XML.
a.

Create an object view.

b.

Create an XMLType view over the object view.

The following sections present examples of creating XML schema-based XMLType
views using object types or object views. They are based on relational tables that
contain employee and department data.
■

"Creating XMLType Employee View, with Nested Department Information"

■

"Creating XMLType Department View, with Nested Employee Information"

The same relational data is used to create each of two XMLType views. In the employee
view, emp_xml, the XML document describes an employee, with the employee's
department as nested information. In the department view, dept_xml, the XML data
describes a department, with the department's employees as nested information.

Creating XMLType Employee View, with Nested Department Information
This section describes how to create XMLType view emp_xml based on object views.
For the last step, there are two alternatives:
■

■

"Step 3a. Create XMLType View emp_xml using Object Type emp_t" – create
XMLType view emp_xml using object type emp_t
"Step 3b. Create XMLType View emp_xml using Object View emp_v" – create
XMLType view emp_xml using object view emp_v

XMLType Views

19-11

Creating XML Schema-Based XMLType Views

Step 1. Create Object Types Example 19–10 creates the object types used in the other
steps.
Example 19–10 Creating Object Types for Schema-Based XMLType Views
CREATE TYPE dept_t AS OBJECT
(deptno NUMBER(4),
dname VARCHAR2(30),
loc
NUMBER(4));
/
CREATE TYPE emp_t AS OBJECT
(empno
NUMBER(6),
ename
VARCHAR2(25),
job
VARCHAR2(10),
mgr
NUMBER(6),
hiredate DATE,
sal
NUMBER(8,2),
comm
NUMBER(2,2),
dept
dept_t);
/

Step 2. Create and Register XML Schema emp_complex.xsd You can create an XML schema
manually, or you can use package DBMS_XMLSCHEMA to generate an XML schema
automatically from existing object types, as shown in Example 19–11.
Example 19–11 Generating an XML Schema with DBMS_
XMLSCHEMA.GENERATESCHEMA
SELECT DBMS_XMLSCHEMA.generateSchema('HR','EMP_T') AS result FROM DUAL;

Example 19–11 generates the XML schema for type emp_t. You can supply various
arguments to PL/SQL function DBMS_XMLSCHEMA.generateSchemas, to add
namespaces, and so on. You can also edit the XML schema to change the default
mappings that are generated. Function generateSchemas generates a list of XML
schemas, one for each SQL database schema that is referenced by the object type and
its object attributes.
Example 19–12 shows how to register XML schema emp_complex.xsd, which
specifies how XML elements and attributes are mapped to corresponding object
attributes in the object types (the xdb:SQLType annotations).
Example 19–12 Registering XML Schema emp_complex.xsd
BEGIN
-- Delete schema if it already exists (else error)
DBMS_XMLSCHEMA.deleteSchema('http://www.oracle.com/emp_complex.xsd', 4);
END;
/
COMMIT;
BEGIN
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'http://www.oracle.com/emp_complex.xsd',
SCHEMADOC => '







































',
=> TRUE,
=> FALSE);

END;
/

Example 19–12 registers the XML schema using the target location
http://www.oracle.com/emp_complex.xsd.

XMLType Views

19-13

Creating XML Schema-Based XMLType Views

Step 3a. Create XMLType View emp_xml using Object Type emp_t Example 19–13 creates an
XMLType view using object type emp_t.
Example 19–13 Creating XMLType View emp_xml
CREATE OR REPLACE VIEW emp_xml OF XMLType
XMLSCHEMA "http://www.oracle.com/emp_complex.xsd"
ELEMENT "Employee"
WITH OBJECT ID (XMLCast(XMLQuery('/Employee/EMPNO'
PASSING OBJECT_VALUE RETURNING CONTENT)
AS BINARY_DOUBLE)) AS
SELECT emp_t(e.employee_id, e.last_name, e.job_id, e.manager_id, e.hire_date,
e.salary, e.commission_pct,
dept_t(d.department_id, d.department_name, d.location_id))
FROM employees e, departments d
WHERE e.department_id = d.department_id;

Example 19–13 uses SQL/XML function XMLCast in the OBJECT ID clause to convert
the XML employee number to SQL data type BINARY_DOUBLE.
Step 3b. Create XMLType View emp_xml using Object View emp_v Example 19–14 creates an
XMLType view based on an object view.
Example 19–14 Creating an Object View and an XMLType View on the Object View
CREATE OR REPLACE VIEW emp_v OF emp_t WITH OBJECT ID (empno) AS
SELECT emp_t(e.employee_id, e.last_name, e.job_id, e.manager_id, e.hire_date,
e.salary, e.commission_pct,
dept_t(d.department_id, d.department_name, d.location_id))
FROM employees e, departments d
WHERE e.department_id = d.department_id;
CREATE OR REPLACE VIEW emp_xml OF XMLType
XMLSCHEMA "http://www.oracle.com/emp_complex.xsd" ELEMENT "Employee"
WITH OBJECT ID DEFAULT AS
SELECT VALUE(p) FROM emp_v p;

Creating XMLType Department View, with Nested Employee Information
This section describes how to create XMLType view dept_xml. Each department in
this view contains nested employee information. For the last step, there are two
alternatives:
■

■

"Step 3a. Create XMLType View dept_xml using Object Type dept_t" – create
XMLType view dept_xml using the object type for a department, dept_t
"Step 3b. Create XMLType View dept_xml using Relational Data Directly" – create
XMLType view dept_xml using relational data directly

Step 1. Create Object Types Example 19–15 creates the object types used in the other
steps.
Example 19–15 Creating Object Types
CREATE TYPE emp_t AS OBJECT (empno
ename
job
mgr
hiredate
sal

19-14 Oracle XML DB Developer's Guide

NUMBER(6),
VARCHAR2(25),
VARCHAR2(10),
NUMBER(6),
DATE,
NUMBER(8,2),

Creating XML Schema-Based XMLType Views

comm

NUMBER(2,2));

/
CREATE OR REPLACE TYPE emplist_t AS TABLE OF emp_t;
/
CREATE TYPE dept_t AS OBJECT (deptno
dname
loc
emps
/

NUMBER(4),
VARCHAR2(30),
NUMBER(4),
emplist_t);

Step 2. Register XML Schema dept_complex.xsd You can either use a pre-existing XML
schema or generate an XML schema from the object type with function DBMS_
XMLSCHEMA.generateSchema or DBMS_XMLSCHEMA.generateSchemas (see
Example 19–11 on page 19-12). Example 19–16 registers the XML schema dept_
complex.xsd.
Example 19–16 Registering XML Schema dept_complex.xsd
BEGIN
-- Delete schema if it already exists (else error)
DBMS_XMLSCHEMA.deleteSchema('http://www.oracle.com/dept_complex.xsd', 4);
END;
/
BEGIN
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'http://www.oracle.com/dept_complex.xsd',
SCHEMADOC => '



















XMLType Views

19-15

Creating XML Schema-Based XMLType Views

LOCAL
GENTYPES






















',
=> TRUE,
=> FALSE);

END;
/

Step 3a. Create XMLType View dept_xml using Object Type dept_t Example 19–17 creates
XMLType view dept_xml using object type dept_t.
Example 19–17 Creating XMLType View dept_xml using Object Type dept_t
CREATE OR REPLACE VIEW dept_xml OF XMLType
XMLSCHEMA "http://www.oracle.com/dept_complex.xsd" ELEMENT "Department"
WITH OBJECT ID (XMLCast(XMLQuery('/Department/DEPTNO'
PASSING OBJECT_VALUE RETURNING CONTENT)
AS BINARY_DOUBLE)) AS
SELECT dept_t(d.department_id, d.department_name, d.location_id,
cast(MULTISET
(SELECT emp_t(e.employee_id, e.last_name, e.job_id,
e.manager_id, e.hire_date,
e.salary, e.commission_pct)
FROM employees e WHERE e.department_id = d.department_id)
AS emplist_t))
FROM departments d;

Step 3b. Create XMLType View dept_xml using Relational Data Directly Alternatively, you can
use SQL/XML publishing functions to create XMLType view dept_xml from the
relational tables without using object type dept_t. Example 19–18 illustrates this.
Example 19–18 Creating XMLType View dept_xml using Relational Data Directly
CREATE OR REPLACE VIEW dept_xml OF XMLType
XMLSCHEMA "http://www.oracle.com/dept_complex.xsd" ELEMENT "Department"
WITH OBJECT ID (XMLCast(XMLQuery('/Department/DEPTNO'

19-16 Oracle XML DB Developer's Guide

Creating XMLType Views from XMLType Tables

PASSING OBJECT_VALUE RETURNING CONTENT)
AS BINARY_DOUBLE)) AS
SELECT
XMLElement(
"Department",
XMLAttributes('http://www.oracle.com/dept_complex.xsd' AS "xmlns",
'http://www.w3.org/2001/XMLSchema-instance' AS "xmlns:xsi",
'http://www.oracle.com/dept_complex.xsd
http://www.oracle.com/dept_complex.xsd'
AS "xsi:schemaLocation"),
XMLForest(d.department_id "DeptNo", d.department_name "DeptName",
d.location_id "Location"),
(SELECT XMLAgg(XMLElement("Employee",
XMLForest(e.employee_id "EmployeeId",
e.last_name "Name",
e.job_id "Job",
e.manager_id "Manager",
e.hire_date "Hiredate",
e.salary "Salary",
e.commission_pct "Commission")))
FROM employees e WHERE e.department_id = d.department_id))
FROM departments d;

XML schema and element information must be specified at
the view level, because the SELECT list could arbitrarily construct
XML of a different XML schema from the underlying table.

Note:

Creating XMLType Views from XMLType Tables
An XMLType view can be created on an XMLType table, for example, to transform the
XML data or to restrict the rows returned.
Example 19–19 creates an XMLType view by restricting the rows included from an
underlying XMLType table. It uses XML schema dept_complex.xsd to create the
underlying table—see "Creating XMLType Department View, with Nested Employee
Information".
Example 19–19 Creating an XMLType View by Restricting Rows from an XMLType Table
CREATE TABLE dept_xml_tab OF XMLType
XMLSchema "http://www.oracle.com/dept_complex.xsd" ELEMENT "Department"
NESTED TABLE XMLDATA."EMPS" STORE AS dept_xml_tab_tab1;
CREATE OR REPLACE VIEW dallas_dept_view OF XMLType
XMLSchema "http://www.oracle.com/dept.xsd" ELEMENT "Department"
AS SELECT OBJECT_VALUE FROM dept_xml_tab
WHERE XMLCast(XMLQuery('/Department/LOC'
PASSING OBJECT_VALUE RETURNING CONTENT)
AS VARCHAR2(20))
= 'DALLAS';
CREATE OR REPLACE VIEW dallas_dept_view OF XMLType

Here, dallas_dept_view restricts the XMLType table rows to those departments
whose location is Dallas.
Example 19–20 shows how you can create an XMLType view by transforming XML
data using a style sheet.

XMLType Views

19-17

Referencing XMLType View Objects using SQL Function REF

Example 19–20 Creating an XMLType View by Transforming an XMLType Table
CREATE OR REPLACE VIEW hr_po_tab OF XMLType
ELEMENT "PurchaseOrder" WITH OBJECT ID DEFAULT AS
SELECT XMLtransform(OBJECT_VALUE, x.col1)
FROM purchaseorder p, xsl_tab x;

Referencing XMLType View Objects using SQL Function REF
You can reference an XMLType view object using SQL function ref:
SELECT ref(d) FROM dept_xml_tab d;

An XMLType view reference is based on one of the following object IDs:
■

System-generated OID — for views on XMLType tables or object views

■

Primary key based OID -- for views with OBJECT ID expressions

These REFs can be used to fetch OCIXMLType instances in the OCI Object cache, or
they can be used in SQL queries. These REFs act the same as REFs to object views.

DML (Data Manipulation Language) on XMLType Views
A given XMLType view might not be implicitly updatable. In that case you must write
INSTEAD-OF TRIGGERS to handle all data manipulation (DML). One way to
determine whether a given XMLType view is implicitly updatable is to query the view
to see whether it is based on an object view or an object constructor that is itself
inherently updatable. Example 19–21 illustrates this.
Example 19–21 Determining Whether an XMLType View is Implicitly Updatable
CREATE TYPE dept_t AS OBJECT
(deptno NUMBER(4),
dname VARCHAR2(30),
loc
NUMBER(4));
/
BEGIN
-- Delete schema if it already exists (else error)
DBMS_XMLSCHEMA.deleteSchema('http://www.oracle.com/dept.xsd', 4);
END;
/
COMMIT;
BEGIN
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'http://www.oracle.com/dept_t.xsd',
SCHEMADOC => '





19-18 Oracle XML DB Developer's Guide

DML (Data Manipulation Language) on XMLType Views

LOCAL
GENTYPES











',
=> TRUE,
=> FALSE);

END;
/
CREATE OR REPLACE VIEW dept_xml of XMLType
XMLSchema "http://www.oracle.com/dept_t.xsd" element "Department"
WITH OBJECT ID (XMLCast(XMLQuery('/Department/DEPTNO'
PASSING OBJECT_VALUE RETURNING CONTENT)
AS BINARY_DOUBLE)) AS
SELECT dept_t(d.department_id, d.department_name, d.location_id)
FROM departments d;
INSERT INTO dept_xml
VALUES (
XMLType.createXML(
'
300
Processing
1700
'));
UPDATE dept_xml d
SET d.OBJECT_VALUE = updateXML(d.OBJECT_VALUE, '/Department/DNAME/text()',
'Shipping')
WHERE XMLExists('/Department[DEPTNO=300]' PASSING OBJECT_VALUE);

XMLType Views

19-19

DML (Data Manipulation Language) on XMLType Views

19-20 Oracle XML DB Developer's Guide

20
Accessing Data Through URIs
This chapter describes how to generate and store URLs in the database and how to
retrieve data pointed to by those URLs. Three kinds of URIs are discussed:
■

DBUris – addresses to relational data in the database

■

XDBUris – addresses to data in Oracle XML DB Repository

■

HTTPUris – Web addresses that use the Hyper Text Transfer Protocol (HTTP(S))

This chapter contains these topics:
■

Overview of Oracle XML DB URL Features

■

URIs and URLs

■

URIType and its Subtypes

■

Accessing Data using URIType Instances

■

XDBUris: Pointers to Repository Resources

■

DBUris: Pointers to Database Data

■

Creating New Subtypes of URIType using Package URIFACTORY

■

SYS_DBURIGEN SQL Function

■

DBUriServlet

Overview of Oracle XML DB URL Features
The two main features described in this chapter are these:
■

■

Using paths as an indirection mechanism – You can store a path in the database and
then access its target indirectly by referring to the path. The paths in question are
various kinds of Uniform Resource Identifier (URI).
Using paths that target database data to produce XML documents – One kind of URI
that you can use for indirection in particular, a DBUri, provides a convenient
XPath notation for addressing database data. You can use a DBUri to construct an
XML document that contains database data and whose structure reflects the
database structure.

URIs and URLs
In developing Web-based XML applications, you often refer to data located on a
network using Uniform Resource Identifiers, or URIs. A URL, or Uniform Resource
Locator, is a URI that accesses an object using an Internet protocol.

Accessing Data Through URIs 20-1

URIType and its Subtypes

A URI has two parts, separated by a number sign (#):
■
■

A URL part, that identifies a document.
A fragment part, that identifies a fragment within the document. The notation for
the fragment depends on the document type. For HTML documents, it is an
anchor name. For XML documents, it is an XPath expression.

These are typical URIs:
■

■

For HTML – http://www.example.com/document1#some_anchor, where
some_anchor is a named anchor in the HTML document.
For XML – http://www.example.com/xml_doc#/po/cust/custname,
where:
–

http://www.example.com/xml_doc identifies the location of the XML
document.

–

/po/cust/custname identifies a fragment within the document. This
portion is defined by the W3C XPointer recommendation.
See Also:
■

■

■

■

http://www.w3.org/2002/ws/Activity.html an
explanation of HTTP(S) URL notation
http://www.w3.org/TR/xpath for an explanation of the
XML XPath notation
http://www.w3.org/TR/xptr/ for an explanation of the
XML XPointer notation
http://xml.coverpages.org/xmlMediaMIME.html for a
discussion of MIME types

URIType and its Subtypes
Oracle XML DB can represent paths of various kinds as database objects. These are the
available path object types:
■

HTTPURIType – An object of this type is called an HTTPUri and represents a URL
that begins with http://. With HTTPURIType, you can create objects that
represent links to remote Web pages (or files) and retrieve those Web pages by
calling object methods. Applications using HTTPUriType must have the proper
access privileges. HTTPUriType implements the Hyper Text Transfer Protocol
(HTTP(S)) for accessing remote Web pages. HTTPURIType uses package UTL_
HTTP to fetch data, so session settings and access control for this package can also
be used to influence HTTP fetches.
See Also:
■

■

■

"HTTPURIType PL/SQL Method GETCONTENTTYPE()" on
page 20-5
Oracle Database Security Guide for information about managing
fine-grained access to external network services

DBURIType – An object of this type is called a DBUri and represents a URI that
targets database data – a table, one or more rows, or a single column. With
DBURIType, you can create objects that represent links to database data, and
retrieve such data as XML by calling object methods. A DBUri uses a simple form

20-2 Oracle XML DB Developer's Guide

URIType and its Subtypes

of XPath expression as its URI syntax – for example, the following XPath
expression is a DBUri reference to the row of table HR.employees where column
first_name has value Jack:
/HR/EMPLOYEES/ROW[FIRST_NAME="Jack"]

See Also :
■

DBUris: Pointers to Database Data on page 20-12

XDBURIType – An object of this type is called an XDBUri, and represents a URI
that targets a resource in Oracle XML DB Repository. With XDBURIType, you can
create objects that represent links to repository resources, and retrieve all or part of
any resource by calling object methods. The URI syntax for an XDBUri is a
repository resource address optionally followed by an XPath expression. For
example, /public/hr/doc1.xml#/purchaseOrder/lineItem is an XDBUri
reference to the lineItem child element of the root element purchaseOrder in
repository file doc1.xml in folder /public/hr.
See Also :

XDBUris: Pointers to Repository Resources on page 20-10

Each of these object types is derived from an abstract object type, URIType. As an
abstract type, it has no instances (objects). Only its subtypes have instances.
Type URIType provides the following features:
■

■

Unified access to data stored inside and outside the server. Because you can use
URIType values to store pointers to HTTP(S) and DBUris, you can create queries
and indexes without worrying about where the data resides.
Mapping of URIs in XML Documents to Database Columns. When an XML document
is broken up and stored in object-relational tables and columns, any URIs
contained in the document are mapped to database columns of the appropriate
URIType subtype.

You can reference data stored in relational columns and expose it to the external world
using URIs. Oracle Database provides a standard servlet, DBUriServlet, that interprets
DBUris. It also provides PL/SQL package UTL_HTTP and Java class java.net.URL,
which you can use to fetch URL references.
URIType columns can be indexed natively in Oracle Database using Oracle Text – no
special data store is needed.
See Also:
■

■

"Creating New Subtypes of URIType using Package
URIFACTORY" on page 20-20 for information about defining
new URIType subtypes
Chapter 6, "Indexing XMLType Data"

DBUris and XDBUris – What For?
The following are typical uses of DBUris and XDBUris:
■

■

You can reference XSLT style sheets from within database-generated Web pages.
PL/SQL package DBMS_METADATA uses DBUris to reference XSL style sheets. An
XDBUri can be used to reference XSLT style sheets stored in Oracle XML DB
Repository.
You can reference HTML text, images and other data stored in the database. URLs
can be used to point to data stored in database tables or in repository folders.

Accessing Data Through URIs 20-3

URIType and its Subtypes

■

■

■

You can improve performance by bypassing the Web server. Replace a global URL
in your XML document with a reference to the database, and use a servlet, a
DBUri, or an XDBUri to retrieve the targeted content. Using a DBUri or an XDBUri
generally provides better performance than using a servlet, because you interact
directly with the database rather than through a Web server.
With a DBUri, you can access an XML document in the database without using
SQL.
Whenever a repository resource is stored in a database table to which you have
access, you can use either an XDBUri or a DBUri to access its content.
See Also: Oracle Database PL/SQL Packages and Types Reference,
"DBMS_METADATA package"

URIType Methods
Abstract object type URIType includes PL/SQL methods that can be used with each of
its subtypes. Each of these methods can be overridden by any of the subtypes.
Table 20–1 lists the URIType PL/SQL methods. In addition, each of the subtypes has a
constructor with the same name as the subtype.
Table 20–1

URIType PL/SQL Methods

URIType Method

Description

getURL()

Returns the URL of the URIType instance.
Use this method instead of referencing a URL directly. URIType subtypes
override this method to provide the correct URL. For example,
HTTPURIType stores a URL without prefix http://. Method getURL()
then prepends the prefix and returns the entire URL.

getExternalURL() Similar to getURL(), but getExternalURL() escapes characters in the
URL, to conform with the URL specification. For example, spaces are
converted to the escaped value %20.
getContentType() Returns the MIME content type for the URI.
HTTPUri: To return the content type, the URL is followed and the MIME
header examined.
DBUri: The returned content type is either text/plain (for a scalar
value) or text/xml (otherwise).
XDBUri: The value of the ContentType metadata property of the
repository resource is returned.
getCLOB()

Returns the target of the URI as a CLOB value. The database character set
is used for encoding the data.
DBUri: XML data is returned (unless node-test text() is used, in which
case the targeted data is returned as is). When a BLOB column is targeted,
the binary data in the column is translated as hexadecimal character data.

getBLOB()

Returns the target of the URI as a BLOB value. No character conversion is
performed, and the character encoding is that of the URI target. This
method can also be used to fetch binary data.
DBUri: When applied to a DBUri that targets a BLOB column, getBLOB()
returns the binary data translated as hexadecimal character data. When
applied to a DBUri that targets non-binary data, the data is returned in the
database character set.

20-4 Oracle XML DB Developer's Guide

URIType and its Subtypes

Table 20–1 (Cont.) URIType PL/SQL Methods
URIType Method

Description

getXML()

Returns the target of the URI as an XMLType instance. Using this, an
application that performs operations other than getCLOB() and
getBLOB() can use XMLType methods to do those operations. This
throws an exception if the URI does not target a well-formed XML
document.

createURI()

Constructs an instance of one of the URIType subtypes.

HTTPURIType PL/SQL Method GETCONTENTTYPE()
HTTPURIType PL/SQL method getContentType() returns the MIME information
for its targeted document. You can use this information to decide whether to retrieve
the document as a BLOB value or a CLOB value. For example, you might treat a Web
page with a MIME type of x/jpeg as a BLOB value, and one with a MIME type of
text/plain or text/html as a CLOB value.
Example 20–1 tests the HTTP content type to determine whether to retrieve data as a
CLOB or BLOB value. The content-type data is the HTTP header, for HTTPURIType, or
the metadata of the database column, for DBURIType.
Example 20–1

Using HTTPURIType PL/SQL Method GETCONTENTTYPE()

DECLARE
httpuri HTTPURIType;
y CLOB;
x BLOB;
BEGIN
httpuri := HTTPURIType('http://www.oracle.com/index.html');
DBMS_OUTPUT.put_line(httpuri.getContentType());
IF httpuri.getContentType() = 'text/html'
THEN
y := httpuri.getCLOB();
END IF;
IF httpuri.getContentType() = 'application-x/bin'
THEN
x := httpuri.getBLOB();
END IF;
END;
/
text/html

DBURIType PL/SQL Method GETCONTENTTYPE()
PL/SQL method getContentType() returns the MIME information for a URL. If a
DBUri targets a scalar value, then the MIME content type returned is text/plain.
Otherwise, the type returned is text/xml.
CREATE TABLE dbtab (a VARCHAR2(20), b BLOB);

DBUris corresponding to the following XPath expressions have content type
text/xml, because each targets a complete column of XML data.
■

/HR/DBTAB/ROW/A

■

/HR/DBTAB/ROW/B

DBUris corresponding to the following XPath expressions have content type
text/plain, because each targets a scalar value.

Accessing Data Through URIs 20-5

Accessing Data using URIType Instances

■

/HR/DBTAB/ROW/A/text()

■

/HR/DBTAB/ROW/B/text()

DBURIType PL/SQL Method GETCLOB()
When PL/SQL method getCLOB() is applied to a DBUri, the targeted data is
returned as XML data, using the targeted column or table name as an XML element
name. If the target XPath uses node-test text(), then the data is returned as text
without an enclosing XML tag. In both cases, the returned data is in the database
character set.
For example: If applied to a DBUri with XPath /HR/DBTAB/ROW/A/text(), where A
is a non-binary column, the data in column A is returned as is. Without XPath
node-test text(), the result is the data wrapped in XML:
...data_in_column_A...

When applied to a DBUri that targets a binary (BLOB) column, the binary data in the
column is translated as hexadecimal character data.
For example: If applied to a DBUri with XPath /HR/DBTAB/ROW/B/text(), where B
is a BLOB column, the targeted binary data is translated to hexadecimal character data
and returned. Without XPath node-test text(), the result is the translated data
wrapped in XML:
...data_translated_to_hex...

DBURIType PL/SQL Method GETBLOB()
When applied to a DBUri that targets a BLOB column, getBLOB() returns the binary
data translated as hexadecimal character data. When applied to a DBUri that targets
non-binary data, getBLOB() returns the data (as a BLOB value) in the database
character set.
For example, consider table dbtab:
CREATE TABLE dbtab (a VARCHAR2(20), b BLOB);

When getBLOB() is applied to a DBUri corresponding to XPath expression
/HR/DBTAB/ROW/B, it returns a BLOB value containing an XML document with root
element B whose content is the hexadecimal-character translation of the binary data of
column B.
When getBLOB() is applied to a DBUri corresponding to XPath expression
/HR/DBTAB/ROW/B/text(), it returns a BLOB value containing only the
hexadecimal-character translation of the binary data of column B.
When getBLOB() is applied to a DBUri corresponding to XPath expression
/HR/DBTAB/ROW/A/text(), which targets non-binary data, it returns a BLOB value
containing the data of column A, in the database character set.

Accessing Data using URIType Instances
To use instances of URIType subtypes for indirection, you generally store such
instances in the database and then use them in queries with a PL/SQL method such as
getCLOB() to retrieve the targeted data. This section illustrates how to do this.
You can create database columns using URIType or any of its subtypes, or you can
store just the text of each URI as a string and then create the needed URIType

20-6 Oracle XML DB Developer's Guide

Accessing Data using URIType Instances

instances on demand, when the URIs are accessed. You can store objects of different
URIType subtypes in the same URIType database column.
You can also define your own object types that inherit from the URIType subtypes.
Deriving new types lets you use custom techniques to retrieve, transform, or filter
data.
See Also:
■

■

"Creating New Subtypes of URIType using Package
URIFACTORY" on page 20-20 for information about defining
new URIType subtypes
"XSL Transformation and Oracle XML DB" on page 3-64 for
information about transforming XML data

Example 20–2 stores an HTTPUri and a DBUri (instances of URIType subtypes
HTTPURIType and DBURIType) in the same database column of type URIType. A
query retrieves the data addressed by each of the URIs. The first URI is a Web-page
URL. The second URI references data in table employees of standard database
schema HR. (For brevity, only the beginning of the Web page is shown.)
Example 20–2

Creating and Querying a URI Column

CREATE TABLE uri_tab (url URIType);
Table created.
INSERT INTO uri_tab VALUES (HTTPURIType.createURI('http://www.oracle.com'));
1 row created.
INSERT INTO uri_tab VALUES (DBURIType.createURI(
'/HR/EMPLOYEES/ROW[FIRST_NAME="Jack"]'));
1 row created.
SELECT e.url.getCLOB() FROM uri_tab e;
E.URL.GETCLOB()
------------------------------------------------------------------


. . .


177
Jack
Livingston
JLIVINGS
011.44.1644.429264
23-APR-06
SA_REP
8400
.2
149
80

2 rows selected.

Accessing Data Through URIs 20-7

Accessing Data using URIType Instances

To use URIType PL/SQL method createURI(), you must know the particular
URIType subtype to use. PL/SQL method getURI() of package URIFACTORY lets
you instead use the flexibility of late binding, determining the particular type
information at run time.
URIFACTORY.getURI() takes as argument a URI string. It returns a URIType
instance of the appropriate subtype (HTTPURIType, DBURIType, or XDBURIType),
based on the form of the URI string:
■
■

■

If the URI starts with http://, then getURI() creates and returns an HTTPUri.
If the URI starts with either /oradb/ or /dburi/, then getURI() creates and
returns a DBUri.
Otherwise, getURI() creates and returns an XDBUri.

Example 20–3 is similar to Example 20–2, but it uses two different ways to obtain
documents targeted by URIs:
■

■

PL/SQL method SYS.URIFACTORY.getURI() with absolute URIs:
–

an HTTPUri that targets HTTP address http://www.oracle.com

–

a DBUri that targets database address
/oradb/HR/EMPLOYEES/ROW[EMPLOYEE_ID=200]

Constructor SYS.HTTPURIType() with a relative URL (no http://). The same
HTTPUri is used as for the absolute URI: the Oracle home page.

In Example 20–3, the URI strings passed to getURI() are hard-coded, but they could
just as easily be string values that are obtained by an application at run time.
Example 20–3

Using Different Kinds of URI, Created in Different Ways

CREATE TABLE uri_tab (docUrl SYS.URIType, docName VARCHAR2(200));
Table created.
-- Insert an HTTPUri with absolute URL into SYS.URIType using URIFACTORY.
-- The target is Oracle home page.
INSERT INTO uri_tab VALUES
(SYS.URIFACTORY.getURI('http://www.oracle.com'), 'AbsURL');
1 row created.
-- Insert an HTTPUri with relative URL using constructor SYS.HTTPURIType.
-- Note the absence of prefix http://. The target is the same.
INSERT INTO uri_tab VALUES (SYS.HTTPURIType('www.oracle.com'), 'RelURL');
1 row created.
-- Insert a DBUri that targets employee data from table HR.employees.
INSERT INTO uri_tab VALUES
(SYS.URIFACTORY.getURI('/oradb/HR/EMPLOYEES/ROW[EMPLOYEE_ID=200]'), 'Emp200');
1 row created.
-- Extract all of the documents.
SELECT e.docUrl.getCLOB(), docName FROM uri_tab e;
E.DOCURL.GETCLOB()
----------------DOCNAME
-----------------------------------



20-8 Oracle XML DB Developer's Guide

Accessing Data using URIType Instances

. . .
AbsURL



. . .
RelURL


200
Jennifer
Whalen
JWHALEN
515.123.4444
17-SEP-03
AD_ASST
4400
101
10

Emp200
3 rows selected.
-- In PL/SQL
CREATE OR REPLACE FUNCTION returnclob
RETURN CLOB
IS a SYS.URIType;
BEGIN
SELECT docUrl INTO a FROM uri_Tab WHERE docName LIKE 'Emp200%';
RETURN a.getCLOB;
END;
/
Function created.
SELECT returnclob() FROM DUAL;
RETURNCLOB()
--------------------------------------------------------------

200
Jennifer
Whalen
JWHALEN
515.123.4444
17-SEP-03
AD_ASST
4400
101
10

1 row selected.

Accessing Data Through URIs 20-9

XDBUris: Pointers to Repository Resources

XDBUris: Pointers to Repository Resources
XDBURIType is a subtype of URIType that provides a way to expose resources in
Oracle XML DB Repository using URIs. Instances of type XDBURIType are called
XDBUris.

XDBUri URI Syntax
The URL portion of an XDBUri URI is the hierarchical address of the targeted
repository resource – it is a repository path (not an XPath expression).
The optional fragment portion of the URI uses the XPath syntax, and is separated from
the URL part by a number-sign (#). It is appropriate only if the targeted resource is an
XML document, in which case the fragment portion targets one or more parts of the
XML document. If the targeted resource is not an XML document, then omit the
fragment and number-sign.
The following are examples of XDBUri URIs:
■

/public/hr/image27.jpg

■

/public/hr/doc1.xml#/PurchaseOrder/LineItem

Based on the form of these URIs:
■

/public/hr is a folder resource in Oracle XML DB Repository.

■

image27.jpg and doc1.xml are resources in folder /public/hr.

■

Resource doc1.xml is a file resource, and it contains an XML document.

■

The XPath expression /PurchaseOrder/LineItem refers to the LineItem
child element in element PurchaseOrder of XML document doc1.xml.

You can create an XDBUri using PL/SQL method getURI() of package URIFACTORY.
XDBURIType is the default URIType used when generating instances using
URIFACTORY PL/SQL method getURI(), unless the URI has one of the recognized
prefixes http://, /dburi, or /oradb.
For example, if resource doc1.xml is present in repository folder /public/hr, then
the following query returns an XDBUri that targets that resource.
SELECT SYS.URIFACTORY.getURI('/public/hr/doc1.xml') FROM DUAL;

It is the lack of a special prefix that determines that the type is XDBURIType, not any
particular resource file extension or the presence of # followed by an XPath expression.
Even if the resource were named foo.bar instead of doc1.xml, the returned
URIType instance would still be an XDBUri.

XDBUri Examples
Example 20–4 creates an XDBUri, inserts values into a purchase-order table, and then
selects all of the purchase orders. Because there is no special prefix used in the URI
passed to URIFACTORY.getURI(), the created URIType instance is an XDBUri.
Example 20–4

Access a Repository Resource by URI using an XDBUri

DECLARE
res BOOLEAN;
postring VARCHAR2(100):= '

999

20-10 Oracle XML DB Developer's Guide

XDBUris: Pointers to Repository Resources

';
BEGIN
res:=DBMS_XDB.createFolder('/public/orders/');
res:=DBMS_XDB.createResource('/public/orders/po1.xml', postring);
END;
/
PL/SQL procedure successfully completed.
CREATE TABLE uri_tab (poUrl SYS.URIType, poName VARCHAR2(1000));
Table created.
-- Create an abstract type column so any type of URI can be used
-- Insert an absolute URL into poUrl.
-- The factory will create an XDBURIType because there is no prefix.
-- Here, po1.xml is an XML file that is stored in /public/orders/
-- of the XML repository.
INSERT INTO uri_tab VALUES
(URIFACTORY.getURI('/public/orders/po1.xml'), 'SomePurchaseOrder');
1 row created.
-- Get all the purchase orders
SELECT e.poUrl.getCLOB(), poName FROM uri_tab e;
E.POURL.GETCLOB()
----------------PONAME
-----

999

SomePurchaseOrder
1 row selected.
-- Using PL/SQL, you can access table uri_tab as follows:
CREATE OR REPLACE FUNCTION returnclob
RETURN CLOB
IS a URIType;
BEGIN
-- Get absolute URL for purchase order named like 'Some%'
SELECT poUrl INTO a FROM uri_tab WHERE poName LIKE 'Some%';
RETURN a.getCLOB();
END;
/
Function created.
SELECT returnclob() FROM DUAL;
RETURNCLOB()
--------------------

999

1 row selected.

Accessing Data Through URIs 20-11

DBUris: Pointers to Database Data

Because PL/SQL method getXML() returns an XMLType instance, you can use it with
SQL/XML functions such as XMLQuery. The query in Example 20–5 illustrates this.
The query retrieves all purchase orders numbered 999.
Example 20–5

Using PL/SQL Method GETXML() with XMLCAST and XMLQUERY

SELECT e.poUrl.getCLOB() FROM uri_tab e
WHERE XMLCast(XMLQuery('$po/ROW/PO'
PASSING e.poUrl.getXML() AS "po"
RETURNING CONTENT)
AS VARCHAR2(24))
= '999';
E.POURL.GETCLOB()
--------------------

999

1 row selected.

DBUris: Pointers to Database Data
A DBUri is a URI that targets database data. As for all instances of URIType subtypes, a
DBUri provides an indirection mechanism for accessing data. In addition, DBURIType
lets you do the following:
■

Address database data using XPath notation. This, in effect, lets you visualize and
access the database as if it were XML data.
For example, a DBUri can use an expression such as
/HR/EMPLOYEES/ROW[FIRST_NAME="Jack"] to target the row of table
HR.employees where column first_name has value Jack.

■

Construct an XML document that contains database data targeted by a DBUri and
whose structure reflects the database structure.
For example: A DBUri with XPath /HR/DBTAB/ROW/A can be used to construct an
XML document that wraps the data of column A in XML elements that reflect the
database structure and are named accordingly:
...data_in_column_A...

A DBUri does not reference a global location as does an HTTPUri. You can, however,
also access objects addressed by a DBUri in a global manner, by appending the DBUri
to an HTTPUri that identifies a servlet that handles DBUris – see "DBUriServlet" on
page 20-26.

Viewing the Database as XML Data
You can access only those database schemas to which you have been granted access
privileges. This portion of the database is, in effect, your own view of the database.
Using DBURIType, you can have corresponding XML views of the database, which are
portions of the database to which you have access, presented in the form of XML data.
This means all kinds database data, not just data that is stored as XML. When
visualized this way, the database data is effectively wrapped in XML elements,
resulting in one or more XML documents.

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DBUris: Pointers to Database Data

Such "XML views" are not database views, in the technical sense of the term. "View"
here means only an abstract perspective that can be useful for understanding
DBURIType. You can think of DBURIType as providing a way to visualize and access
the database as if it were XML data.
However, DBURIType does not just provide an exercise in visualization and an
additional means to access database data. Each "XML view" can be realized as an XML
document – that is, you can use DBURIType to generate XML documents using
database data.
All of this is another way of saying that DBURIType lets you use XPath notation to 1)
address and access any database data to which you have access and 2) construct XML
representations of that data.
Figure 20–1 illustrates the relation between a relational table, HR.employees, a
corresponding XML view of a portion of that table, and the corresponding DBUri URI
(a simple XPath expression). In this case, the portion of the data exposed as XML is the
row where employee_id is 200. The URI can be used to access the data and
construct an XML document that reflects the "XML view".
Figure 20–1 A DBUri Corresponds to an XML Visualization of Relational Data

DBUri: /oradb/HR/EMPLOYEES/ROW[EMPLOYEE_ID=200]/LAST_NAME

Database

hr.employees
employee_id

last_name

200
177

Whalen
Livingston

Relational Data





200
XML

Visualization

Whalen




XML Document

The XML elements in the "XML view" and the steps in the URI XPath expression both
reflect the database table and column names. Note the use of ROW to indicate a row in
the database table – both in the "XML view" and in the URI XPath expression.
Note also that the XPath expression contains a root-element step, oradb. This is used
to indicate that the URI corresponds to a DBUri, not an HTTPUri or an XDBUri.
Whenever this correspondence is understood from context, this XPath step can be
skipped. For example, if it is known that the path in question is a path to database
data, the following URIs are equivalent:
■

/oradb/HR/EMPLOYEES/ROW[EMPLOYEE_ID=200]/LAST_NAME

■

/HR/EMPLOYEES/ROW[EMPLOYEE_ID=200]/LAST_NAME

Whenever the URI context is not clear, however, you must use the prefix /oradb to
distinguish a URI as corresponding to a DBUri. In particular, you must supply the
prefix to URIFACTORY PL/SQL methods and to DBUriServlet.

Accessing Data Through URIs 20-13

DBUris: Pointers to Database Data

See Also:
■

■
■

"Creating New Subtypes of URIType using Package
URIFACTORY" on page 20-20
"DBUriServlet" on page 20-26
Chapter 18, "Generating XML Data from the Database" for other
ways to generate XML from database data

DBUri URI Syntax
An XPath expression is a path into XML data that addresses one or more XML nodes.
A DBUri exploits the notion of a virtual XML user visualization of the database to use
a simple form of XPath expression as a URI to address database data. This is so,
regardless of the type of data, in particular, whether or not the data is XML.
Thus, for DBURIType, Oracle Database supports only a subset of the full XPath or
XPointer syntax. There are no syntax restrictions for XDBUri XPath expressions. There
is also an exception in the DBUri case: data in XMLType tables. For an XMLType table,
the simple XPath form is used to address the table itself within the database. Then, to
address particular XML data in the table, the remainder of the XPath expression can
use the full XPath syntax. This exception applies only to XMLType tables, not to
XMLType columns.
In any case, unlike an XDBUri, a DBUri URI does not use a number-sign (#) to
separate the URL portion of a URI from a fragment (XPath) portion. DBURIType does
not use URI fragments. Instead, the entire URI is treated as a (simple) XPath
expression.
You can create DBUris to any database data to which you have access. XPath
expressions such as the following are allowed:
■

/database_schema/table

■

/database_schema/table/ROW[predicate_expression]/column

■

/database_schema/table/ROW[predicate_expression]/object_
column/attribute

■

/database_schema/XMLType_table/ROW/XPath_expression

In the last case, XMLType_table is an XMLType table, and XPath_expression is
any XPath expression. For tables that are not XMLType, a DBUri XPath expression must
end at a column (it cannot address specific data inside a column). This restriction
includes XMLType columns, LOB columns, and VARCHAR2 columns that contain XML
data.
A DBUri XPath expression can do any of the following:
■

Target an entire table.
For example, /HR/EMPLOYEES targets table employees of database schema HR.

■

Include XPath predicates at any step in the path, except the database schema and
table steps.
For example, /HR/EMPLOYEES/ROW[EMPLOYEE_ID=200]/EMAIL targets
column email of table HR.employees, where employee_id is 200.

■

Use the text() XPath node test on data with scalar content. This is the only node
test that can be used, and it cannot be used with the table or row step.

The following can be used in DBUri (XPath) predicate expressions:

20-14 Oracle XML DB Developer's Guide

DBUris: Pointers to Database Data

■

Boolean operators and, or, and not

■

Relational operators <, >, <=, !=, >=, =, mod, div, * (multiply)

A DBUri XPath expression must do all of the following:
■
■

Use only the child XPath axis – other axes, such as parent, are not allowed.
Either specify a database schema or specify PUBLIC to resolve the table name
without a specific schema.

■

Specify a database view or table name.

■

Include a ROW step, if a database column is targeted.

■

Identify a single data value, which can be an object-type instance or a collection.

■

Result in well-formed XML when it is used to generate XML data using database
data.
An example of a DBUri that does not result in well-formed XML is
/HR/EMPLOYEES/ROW/LAST_NAME. It returns more than one 
element fragment, with no single root element.

■

Use none of the following:
■

* (wildcard)

■

. (self)

■

.. (parent)

■

// (descendant or self)

■

XPath functions, such as count

A DBUri XPath expression can optionally be prefixed by /oradb or /dburi (the two
are equivalent) to distinguish it. This prefix is case-insensitive. However, the rest of the
DBUri XPath expression is case-sensitive, as are XPath expressions generally. Thus, for
example, to specify table HR.employees as a DBUri XPath expression, you must use
HR/EMPLOYEES, not hr/employees (or a mixed-case combination), because table
and column names are uppercase, by default.
See Also:

http://www.w3.org/TR/xpath on XPath notation

DBUris are Scoped to a Database and Session
The content of the XML views you have of the database, and hence of the XML
documents that you can construct, reflects the permissions you have for accessing
particular database data at a given time. That is, a DBUri is scoped to a given database
session, so the same DBUri can give different results in the same query, depending on
the session context (which user is connected and what privileges the user has).
To complicate things a bit, there is also an XML element PUBLIC, under which
database data is accessible without any database-schema qualification. This is a
convenience feature, but it can also lead to some confusion if you forget that the XML
views of the database for a given user depend on the specific access the user has to the
database at a given time.
XML element PUBLIC corresponds to the use of a public synonym. For example, when
queried by user quine, the following query tries to match table foo under database
schema quine, but if no such table exists, it tries to match a public synonym named
foo.
SELECT * FROM foo;

Accessing Data Through URIs 20-15

DBUris: Pointers to Database Data

In the same way, XML element PUBLIC contains all of the database data visible to a
given user and all of the data visible to that user through public synonyms. So, the
same DBUri URI /PUBLIC/FOO can resolve to quine.foo when user quine is
connected, and resolve to curry.foo when user curry is connected.

DBUri Examples
A DBUri can identify a table, a row, a column in a row, or an attribute of an object
column. The following sections describe how to target different object types.

Targeting a Table
You can target a complete database table, using this syntax:
/database_schema/table

Example 20–6 uses a DBUri that targets a complete table. An XML document is
returned that corresponds to the table contents. The top-level XML element is named
for the table. The values of each row are enclosed in a ROW element.
Example 20–6

Targeting a Complete Table using a DBUri

CREATE TABLE uri_tab (url URIType);
Table created.
INSERT INTO uri_tab VALUES
(DBURIType.createURI('/HR/EMPLOYEES'));
1 row created.
SELECT e.url.getCLOB() FROM uri_tab e;
E.URL.GETCLOB()
--------------


100
Steven
King
SKING
515.123.4567
17-JUN-03
AD_PRES
24000
90


101
Neena
Kochhar
NKOCHHAR
515.123.4568
21-SEP-05
AD_VP
17000
100
90

. . .

20-16 Oracle XML DB Developer's Guide

DBUris: Pointers to Database Data

1 row selected.

Targeting a Row in a Table
You can target one or more specific rows of a table, using this syntax:
/database_schema/table/ROW[predicate_expression]

Example 20–7 uses a DBUri that targets a single table row. The XPath predicate
expression identifies the single table row that corresponds to employee number 200.
The result is an XML document with ROW as the top-level element.
Example 20–7

Targeting a Particular Row in a Table using a DBUri

CREATE TABLE uri_tab (url URIType);
Table created.
INSERT INTO uri_tab VALUES
(DBURIType.createURI('/HR/EMPLOYEES/ROW[EMPLOYEE_ID=200]'));
1 row created.
SELECT e.url.getCLOB() FROM uri_tab e;
E.URL.GETCLOB()
------------------------------------------------------

200
Jennifer
Whalen
JWHALEN
515.123.4444
17-SEP-03
AD_ASST
4400
101
10

1 row selected.

Targeting a Column
You can target a specific column, using this syntax:
/database_schema/table/ROW[predicate_expression]/column

You can target a specific attribute of an object column, using this syntax:
/database_schema/table/ROW[predicate_expression]/object_column/attribute

You can target a specific object column whose attributes have specific values, using
this syntax:
/database_schema/table/ROW[predicate_expression_with_attributes]/object_column

Example 20–8 uses a DBUri that targets column last_name for the same employee as
in Example 20–7. The top-level XML element is named for the targeted column.

Accessing Data Through URIs 20-17

DBUris: Pointers to Database Data

Example 20–8

Targeting a Specific Column using a DBUri

CREATE TABLE uri_tab (url URIType);
Table created.
INSERT INTO uri_tab VALUES
(DBURIType.createURI('/HR/EMPLOYEES/ROW[EMPLOYEE_ID=200]/LAST_NAME'));
1 row created.
SELECT e.url.getCLOB() FROM uri_tab e;
E.URL.GETCLOB()
-----------------------------
Whalen
1 row selected.

Example 20–9 uses a DBUri that targets a CUST_ADDRESS object column containing
city and postal code attributes with certain values. The top-level XML element is
named for the column, and it contains child elements for each of the object attributes.
Example 20–9

Targeting an Object Column with Specific Attribute Values using a DBUri

CREATE TABLE uri_tab (url URIType);
Table created.
INSERT INTO uri_tab VALUES
(DBURIType.createURI(
'/OE/CUSTOMERS/ROW[CUST_ADDRESS/CITY="Poughkeepsie" and
CUST_ADDRESS/POSTAL_CODE=12601]/CUST_ADDRESS'));
1 row created.
SELECT e.url.getCLOB() FROM uri_tab e;
E.URL.GETCLOB()
--------------

33 Fulton St
12601
Poughkeepsie
NY
US

1 row selected.

The DBUri identifies the object that has a CITY attribute with Poughkeepsie as value
and a POSTAL_CODE attribute with 12601 as value.

Retrieving the Text Value of a Column
In many cases, it can be useful to retrieve only the text values of a column and not the
enclosing tags. For example, if XSLT style sheets are stored in a CLOB column, you can
retrieve the document text without having any enclosing column-name tags. You can
use the text() XPath node test for this. It specifies that you want only the text value
of the node. Use the following syntax:
/oradb/database_schema/table/ROW[predicate_expression]/column/text()

20-18 Oracle XML DB Developer's Guide

DBUris: Pointers to Database Data

Example 20–10 retrieves the text value of the employee last_name column for
employee number 200, without the XML tags.
Example 20–10 Retrieve Only the Text Value of a Node using a DBUri
CREATE TABLE uri_tab (url URIType);
Table created.
INSERT INTO uri_tab VALUES
(DBURIType.createURI(
'/HR/EMPLOYEES/ROW[EMPLOYEE_ID=200]/LAST_NAME/text()'));
1 row created.
SELECT e.url.getCLOB() FROM uri_tab e;
E.URL.GETCLOB()
--------------Whalen
1 row selected.

Targeting a Collection
You can target a database collection, such as an ordered collection table. You must,
however, target the entire collection – you cannot target individual members of a
collection. When a collection is targeted, the XML document produced by the DBUri
contains each collection member as an XML element, with all such elements enclosed
in a element named for the type of the collection.
Example 20–11 uses a DBUri that targets a collection of numbers. The top-level XML
element is named for the collection, and its children are named for the collection type
(NUMBER).
Example 20–11 Targeting a Collection using a DBUri
CREATE TYPE num_collection AS VARRAY(10) OF NUMBER;
/
Type created.
CREATE TABLE orders (item VARCHAR2(10), quantities num_collection);
Table created.
INSERT INTO orders VALUES ('boxes', num_collection(3, 7, 4, 9));
1 row created.
SELECT * FROM orders;
ITEM
---QUANTITIES
---------boxes
NUM_COLLECTION(3, 7, 4, 9)
1 row selected.
SELECT DBURIType('/HR/ORDERS/ROW[ITEM="boxes"]/QUANTITIES').getCLOB() FROM DUAL;
DBURITYPE('/HR/ORDERS/ROW[ITEM="BOXES"]/QUANTITIES').GETCLOB()

Accessing Data Through URIs 20-19

Creating New Subtypes of URIType using Package URIFACTORY

-------------------------------------------------------------

3
7
4
9

1 row selected.

Creating New Subtypes of URIType using Package URIFACTORY
You can use PL/SQL package URIFACTORY to do more than create URIType
instances. Additional PL/SQL methods are listed in Table 20–2.
Table 20–2

URIFACTORY PL/SQL Methods

PL/SQL Method

Description

getURI()

Returns the URL of the URIType instance.

escapeURI()

Escapes the URI string by replacing characters that are not permitted in URIs by
their equivalent escape sequence.

unescapeURI()

Removes escaping from a given URI.

registerURLHandler()

Registers a particular type name for handling a particular URL. This is called by
getURI() to generate an instance of the type.
A Boolean argument can be used to indicate that the prefix must be stripped off
before calling the appropriate type constructor.

unregisterURLHandler() Unregisters a URL handler.

Of particular note is that you can use package URIFACTORY to define new subtypes of
type URIType. You can then use those subtypes to provide specialized processing of
URIs. In particular, you can define URIType subtypes that correspond to particular
protocols – URIFACTORY then recognizes and processes instances of those subtypes
accordingly.
Defining new types and creating database columns specific to the new types has these
advantages:
■

■

It provides an implicit constraint on the columns to contain only instances of those
types. This can be useful for implementing specialized indexes on a column for
specific protocols. For a DBUri, for instance, you can implement specialized
indexes that fetch data directly from disk blocks, rather than executing SQL
queries.
You can have different constraints on different columns, based on the type. For a
HTTPUri, for instance, you can define proxy and firewall constraints on a column,
so that any access through the HTTP uses the proxy server.

Registering New URIType Subtypes with Package URIFACTORY
To provide specialized processing of URIs, you define and register a new URIType
subtype, as follows:
1.

Create the new type using SQL statement CREATE TYPE. The type must
implement PL/SQL method createURI().

20-20 Oracle XML DB Developer's Guide

Creating New Subtypes of URIType using Package URIFACTORY

2.

Optionally override the default methods, to perform specialized processing when
retrieving data or to transform the XML data before displaying it.

3.

Choose a new URI prefix, to identify URIs that use this specialized processing.

4.

Register the new prefix using PL/SQL method registerURLHandler(), so that
package URIFACTORY can create an instance of your new subtype when it receives
a URI starting with the new prefix you defined.

After the new subtype is defined, a URI with the new prefix is recognized by
URIFACTORY methods, and you can create and use instances of the new type.
For example, suppose that you define a new protocol prefix, ecom://, and define a
subtype of URIType to handle it. Perhaps the new subtype implements some special
logic for PL/SQL method getCLOB(), or perhaps it makes some changes to XML tags
or data in method getXML(). After you register prefix ecom:// with URIFACTORY, a
call to getURI() generates an instance of the new URIType subtype for a URI with
that prefix.
Example 20–12 creates a new type, ECOMURIType, to handle a new protocol,
ecom://. The example stores three different kinds of URIs in a single table: an
HTTPUri, a DBUri, and an instance of the new type, ECOMURIType. To run this
example, you would need to define each of the ECOMURIType member functions.
Example 20–12 URIFACTORY: Registering the ECOM Protocol
CREATE TABLE url_tab (urlcol varchar2(80));
Table created.
-- Insert an HTTP URL reference
INSERT INTO url_tab VALUES ('http://www.oracle.com/');
1 row created.
-- Insert a DBUri
INSERT INTO url_tab VALUES ('/oradb/HR/EMPLOYEES/ROW[FIRST_NAME="Jack"]');
1 row created.
-- Create a new type to handle a new protocol called ecom://
-- This is just an example template. For this to run, the implementations
-- of these functions must be specified.
CREATE OR REPLACE TYPE ECOMURIType UNDER SYS.URIType (
OVERRIDING MEMBER FUNCTION getCLOB RETURN CLOB,
OVERRIDING MEMBER FUNCTION getBLOB RETURN BLOB,
OVERRIDING MEMBER FUNCTION getExternalURL RETURN VARCHAR2,
OVERRIDING MEMBER FUNCTION getURI RETURN VARCHAR2,
-- Must have this for registering with the URL handler
STATIC FUNCTION createURI(url IN VARCHAR2) RETURN ECOMURIType);
/
-- Register a new handler for the ecom:// prefixes
BEGIN
-- The handler type name is ECOMURIType; schema is HR
-- Ignore the prefix case, so that URIFACTORY creates the same subtype
-- for URIs beginning with ECOM://, ecom://, eCom://, and so on.
-- Strip the prefix before calling PL/SQL method createURI(),
-- so that the string 'ecom://' is not stored inside the
-- ECOMURIType object. It is added back automatically when
-- you call ECOMURIType.getURI().
URIFACTORY.registerURLHandler (prefix => 'ecom://',
schemaname => 'HR',
typename => 'ECOMURITYPE',
ignoreprefixcase => TRUE,

Accessing Data Through URIs 20-21

SYS_DBURIGEN SQL Function

stripprefix => TRUE);
END;
/
PL/SQL procedure successfully completed.
-- Insert this new type of URI into the table
INSERT INTO url_tab VALUES ('ECOM://company1/company2=22/comp');
1 row created.
-- Use the factory to generate an instance of the appropriate
-- subtype for each URI in the table.
-- You would need to define the member functions for this to work:
SELECT urifactory.getURI(urlcol) FROM url_tab;
-- This would generate:
HTTPURIType('www.oracle.com'); -- an HTTPUri
DBURIType('/oradb/HR/EMPLOYEES/ROW[FIRST_NAME="Jack"]', null); -- a DBUri
ECOMURIType('company1/company2=22/comp'); -- an ECOMURIType instance

SYS_DBURIGEN SQL Function
You can create a DBUri by providing an XPath expression to constructor DBURIType
or to appropriate URIFACTORY PL/SQL methods. With Oracle SQL function sys_
DburiGen, you can alternatively create a DBUri with an XPath that is composed from
database columns and their values.
Oracle SQL function sys_DburiGen takes as its argument one or more database
columns or attributes, and optionally a rowid, and generates a DBUri that targets a
particular column or row object. Function sys_DburiGen takes an additional
parameter that indicates whether the text value of the node is needed. See Figure 20–2.
Figure 20–2 SYS_DBURIGEN Syntax
,
column
SYS_DBURIGEN

rowid

,

’

text

(

)

’

(

)
attribute

All columns or attributes referenced must reside in the same table. They must each
reference a unique value. If you specify multiple columns, then the initial columns
identify the row, and the last column identifies the column within that row. If you do
not specify a database schema, then the table name is interpreted as a public synonym.
See Also:

Oracle Database SQL Language Reference

Example 20–13 uses Oracle SQL function sys_DburiGen to generate a DBUri that
targets column email of table HR.employees where employee_id is 206:
Example 20–13 SYS_DBURIGEN: Generating a DBUri that Targets a Column
SELECT sys_DburiGen(employee_id, email)
FROM employees
WHERE employee_id = 206;
SYS_DBURIGEN(EMPLOYEE_ID,EMAIL)(URL, SPARE)
-------------------------------------------------------------------

20-22 Oracle XML DB Developer's Guide

SYS_DBURIGEN SQL Function

DBURITYPE('/PUBLIC/EMPLOYEES/ROW[EMPLOYEE_ID = "206"]/EMAIL', NULL)
1 row selected.

Rules for Passing Columns or Object Attributes to SYS_DBURIGEN
A column or attribute passed to Oracle SQL function sys_DburiGen must obey the
following rules:
■

■

Same table: All columns referenced in function sys_DburiGen must come from
the same table or view.
Unique mapping: The column or object attribute must be uniquely mappable back
to the table or view from which it came. The only virtual columns allowed are
those produced with value or ref. The column can come from a subquery with a
SQL TABLE collection expression, that is, TABLE(...), or from an inline view (as
long as the inline view does not rename the columns).
See Oracle Database SQL Language Reference for information about the SQL TABLE
collection expression.

■

■

■

Key columns: Either the rowid or a set of key columns must be specified. The list of
key columns is not required to be declared as a unique or primary key, as long as
the columns uniquely identify a particular row in the result.
PUBLIC element: If the table or view targeted by the rowid or key columns does
not specify a database schema, then the PUBLIC keyword is used. When a DBUri
is accessed, the table name resolves to the same table, synonym, or database view
that was visible by that name when the DBUri was created.
Optional text() argument: By default, DBURIType constructs an XML document.
Use text() as the third argument to sys_DburiGen to create a DBUri that
targets a text node (no XML elements). For example:
SELECT sys_DburiGen(employee_id, last_name, 'text()') FROM hr.employees,
WHERE employee_id=200;

This constructs a DBUri with the following URI:
/HR/EMPLOYEES/ROW[EMPLOYEE_ID=200]/LAST_NAME/text()
■

Single-column argument: If there is a single-column argument, then the column is
used as both the key column to identify the row and the referenced column.

The query in Example 20–14 uses employee_id as both the key column and the
referenced column. It generates a DBUri that targets the row with employee_id 200.
Example 20–14 Passing Columns with Single Arguments to SYS_DBURIGEN
SELECT sys_DburiGen(employee_id) FROM employees
WHERE employee_id=200;
SYS_DBURIGEN(EMPLOYEE_ID)(URL, SPARE)
------------------------------------DBURITYPE('/PUBLIC/EMPLOYEES/ROW[EMPLOYEE_ID=''200'']/EMPLOYEE_ID', NULL)
1 row selected.

Accessing Data Through URIs 20-23

SYS_DBURIGEN SQL Function

SYS_DBURIGEN SQL Function: Examples
Example 20–15 Inserting Database References using SYS_DBURIGEN
CREATE TABLE doc_list_tab (docno NUMBER PRIMARY KEY, doc_ref SYS.DBURIType);
Table created.
-- Insert a DBUri that targets the row with employee_id=177
INSERT INTO doc_list_tab VALUES(1001, (SELECT sys_DburiGen(rowid, employee_id)
FROM employees WHERE employee_id=177));
1 row created.
-- Insert a DBUri that targets the last_name column of table employees
INSERT INTO doc_list_tab VALUES(1002,
(SELECT sys_DburiGen(employee_id, last_name)
FROM employees WHERE employee_id=177));
1 row created.
SELECT * FROM doc_list_tab;
DOCNO
---------DOC_REF(URL, SPARE)
----------------------------------------------------1001
DBURITYPE('/PUBLIC/EMPLOYEES/ROW[ROWID=''AAAQCcAAFAAAABSABN'']/EMPLOYEE_ID', NULL)
1002
DBURITYPE('/PUBLIC/EMPLOYEES/ROW[EMPLOYEE_ID=''177'']/LAST_NAME', NULL)
2 rows selected.

Returning Partial Results
When selecting from a large column, you might sometimes want to retrieve only a
portion of the result, and create a URL to the column instead. For example, consider
the case of a travel story Web site. If travel stories are stored in a table, and users
search for a set of relevant stories, then you do not want to list each entire story in the
search-result page. Instead, you might show just the first 20 characters of each story, to
represent the gist, and then return a URL to the full story. This can be done as follows:
Example 20–16 creates the travel story table.
Example 20–16 Creating the Travel Story Table
CREATE TABLE travel_story (story_name VARCHAR2(100), story CLOB);
Table created.
INSERT INTO travel_story
VALUES ('Egypt', 'This is the story of my time in Egypt....');
1 row created.

Example 20–17 creates a function that returns only the first 20 characters from the
story.
Example 20–17 A Function that Returns the First 20 Characters
CREATE OR REPLACE FUNCTION charfunc(clobval IN CLOB) RETURN VARCHAR2 IS
res VARCHAR2(20);
amount NUMBER := 20;

20-24 Oracle XML DB Developer's Guide

SYS_DBURIGEN SQL Function

BEGIN
DBMS_LOB.read(clobval, amount, 1, res);
RETURN res;
END;
/
Function created.

Example 20–18 creates a view that selects only the first twenty characters from the
travel story, and returns a DBUri to the story column.
Example 20–18 Creating a Travel View for Use with SYS_DBURIGEN
CREATE OR REPLACE VIEW travel_view AS
SELECT story_name, charfunc(story) short_story,
sys_DburiGen(story_name, story, 'text()') story_link
FROM travel_story;
View created.
SELECT * FROM travel_view;
STORY_NAME
---------SHORT_STORY
----------STORY_LINK(URL, SPARE)
---------------------Egypt
This is the story of
DBURITYPE('/PUBLIC/TRAVEL_STORY/ROW[STORY_NAME=''Egypt'']/STORY/text()', NULL)
1 row selected.

RETURNING URLs to Inserted Objects
You can use Oracle SQL function sys_DburiGen in the RETURNING clause of DML
statements to retrieve the URL of an object as it is inserted.
In Example 20–19, whenever a document is inserted into table clob_tab, its URL is
inserted into table uri_tab. This is done using Oracle SQL function sys_DburiGen
in the RETURNING clause of the INSERT statement.
Example 20–19 Retrieving a URL using SYS_DBURIGEN in RETURNING Clause
CREATE TABLE clob_tab (docid NUMBER, doc CLOB);
Table created.
CREATE TABLE uri_tab (docs SYS.DBURIType);
Table created.

In PL/SQL, specify the storage of the URL of the inserted document as part of the
insertion operation, using the RETURNING clause and EXECUTE IMMEDIATE:
DECLARE
ret SYS.DBURIType;
BEGIN
-- execute the insert operation and get the URL
EXECUTE IMMEDIATE
'INSERT INTO clob_tab VALUES (1, ''TEMP CLOB TEST'')
RETURNING sys_DburiGen(docid, doc, ''text()'') INTO :1'
RETURNING INTO ret;
-- Insert the URL into uri_tab

Accessing Data Through URIs 20-25

DBUriServlet

INSERT INTO uri_tab VALUES (ret);
END;
/
SELECT e.docs.getURL() FROM hr.uri_tab e;
E.DOCS.GETURL()
-----------------------------------------------/ORADB/PUBLIC/CLOB_TAB/ROW[DOCID='1']/DOC/text()
1 row selected.

DBUriServlet
Oracle XML DB Repository resources can be retrieved using the HTTP server that is
incorporated in Oracle XML DB. Oracle Database also includes a servlet,
DBUriServlet, that makes any kind of database data available through HTTP(S) URLs.
The data can be returned as plain text, HTML, or XML.
A Web client or application can access such data without using SQL or a specialized
database API. You can retrieve the data by linking to it on a Web page or by requesting
it through HTTP-aware APIs of Java, PL/SQL, and Perl. You can display or process the
data using an application such as a Web browser or an XML-aware spreadsheet.
DBUriServlet can generate content that is XML data or not, and it can transform the
result using XSLT style sheets.
You make database data Web-accessible by using a URI that is composed of a servlet
address (URL) plus a DBUri URI that specifies which database data to retrieve. This is
the syntax, where http://server:port is the URL of the servlet (server and port),
and /oradb/database_schema/table is the DBUri URI (any DBUri URI can be
used):
http://server:port/oradb/database_schema/table

When using XPath notation in a URL for the servlet, you might need to escape certain
characters. You can use URIType PL/SQL method getExternalURL() to do this.
You can either use DBUriServlet, which is pre-installed as part of Oracle XML DB,
or write your own servlet that runs on a servlet engine. The servlet reads the URI
portion of the invoking URL, creates a DBUri using that URI, calls URIType PL/SQL
methods to retrieve the data, and returns the values in a form such as a Web page, an
XML document, or a plain-text document.
The MIME type to use is specified to the servlet through the URI:
■

■

By default, the servlet produces MIME types text/xml and text/plain. If the
DBUri path ends in text(), then text/plain is used. Otherwise, an XML
document is generated with MIME type text/xml.
You can override the default MIME type, setting it to binary/x-jpeg or some
other value, by using the contenttype argument to the servlet.
See Also: Chapter 32, "Writing Oracle XML DB Applications in
Java", for information about Oracle XML DB servlets

Table 20–3 describes each of the optional URL parameters you can pass to
DBUriServlet to customize its output.

20-26 Oracle XML DB Developer's Guide

DBUriServlet

Table 20–3

DBUriServlet: Optional Arguments

Argument

Description

rowsettag

Changes the default root tag name for the XML document. For example:
http://server:8080/oradb/HR/EMPLOYEES?rowsettag=OracleEmployees

contenttype Specifies the MIME type of the generated document. For example:
http://server:8080/oradb/HR/EMPLOYEES?contenttype=text/plain
transform

Passes a URL to URIFACTORY, which retrieves the XSL style sheet at that
location. This style sheet is then applied to the XML document being returned by
the servlet. For example:
http://server:8080/oradb/HR/EMPLOYEES?transform=/oradb/QUINE/XSLS/DOC
/text()&contenttype=text/html

Overriding the MIME Type using a URL
To retrieve the employee_id column of the employee table, you can use a URL such
as one of the following, where computer server.oracle.com is running Oracle
Database with a Web service listening to requests on port 8080. Step oradb is the
virtual path that maps to the servlet.
http://server.oracle.com:8080/oradb/QUINE/A/ROW[B=200]/C/text()

Produces a content type of text/plain
http://server.oracle.com:8080/oradb/QUINE/A/ROW[B=200]/C

Produces a content type of text/xml
To override the content type, you can use a URL that passes text/html to the servlet
as the contenttype parameter:
http://server.oracle.com:8080/oradb/QUINE/A/ROW[B=200]/C?contenttype=text/html

Produces a content type of text/html

Customizing DBUriServlet
DBUriServlet is built into the database – to customize the servlet, you must edit the
Oracle XML DB configuration file, xdbconfig.xml. You can edit it with database
schema (user account) XDB, using WebDAV, FTP, Oracle Enterprise Manager, or
PL/SQL. To update the file using FTP or WebDAV, download the document, edit it,
and save it back into the database.
See Also:
■

Chapter 32, "Writing Oracle XML DB Applications in Java"

■

Chapter 34, "Administering Oracle XML DB"

■

Oracle Database 2 Day + Security Guide for information about
database schema XDB

DBUriServlet is installed at /oradb/*, which is the address specified in the
servlet-pattern tag of xdbconfig.xml. The asterisk (*) is necessary to indicate
that any path following oradb is to be mapped to the same servlet. oradb is
published as the virtual path. You can change the path that is used to access the
servlet.
In Example 20–20, the configuration file is modified to install DBUriServlet under
/dburi/*.

Accessing Data Through URIs 20-27

DBUriServlet

Example 20–20 Changing the Installation Location of DBUriServlet
DECLARE
doc XMLType;
doc2 XMLType;
BEGIN
doc := DBMS_XDB.cfg_get();
SELECT
updateXML(doc,
'/xdbconfig/sysconfig/protocolconfig/httpconfig/webappconfig/servletconfig/
servlet-mappings/servlet-mapping[servlet-name="DBUriServlet"]/servlet-pattern/
text()',
'/dburi/*')
INTO doc2 FROM DUAL;
DBMS_XDB.cfg_update(doc2);
COMMIT;
END;
/

Security parameters, the servlet display-name, and the description can also be
customized in configuration file xdbconfig.xml. The servlet can be removed by
deleting its servlet-pattern. This can also be done using Oracle SQL function
updateXML to update the servlet-mapping element to NULL.

DBUriServlet Security
Servlet security is handled by Oracle Database using roles. When users log in to the
servlet, they use their database user name and password. The servlet checks to ensure
that the user logging has one of the roles specified in the configuration file using
parameter security-role-ref). By default, the servlet is available to role
authenticatedUser, and any user who logs into the servlet with a valid database
password has this role.
The role parameter can be changed to restrict access to any specific database roles. To
change from the default authenticatedUser role to a role that you have created,
you modify the Oracle XML DB configuration file.
Example 20–21 changes the default role authenticatedUser to role
servlet-users (which you must have created).
Example 20–21 Restricting Servlet Access to a Database Role
DECLARE
doc XMLType;
doc2 XMLType;
doc3 XMLType;
BEGIN
doc := DBMS_XDB.cfg_get();
SELECT updateXML(doc,
'/xdbconfig/sysconfig/protocolconfig/httpconfig/webappconfig/servletconfig/
servlet-list/servlet[servlet-name="DBUriServlet"]/security-role-ref/role-name/
text()',
'servlet-users')
INTO doc2 FROM DUAL;
SELECT updateXML(doc2,
'/xdbconfig/sysconfig/protocolconfig/httpconfig/webappconfig/servletconfig/
servlet-list/servlet[servlet-name="DBUriServlet"]/security-role-ref/role-link/
text()',
'servlet-users')
INTO doc3 FROM DUAL;

20-28 Oracle XML DB Developer's Guide

DBUriServlet

DBMS_XDB.cfg_update(doc3);
COMMIT;
END;
/

Configuring Package URIFACTORY to Handle DBUris
A URL such as http://server/servlets/oradb is handled by DBUriServlet (or
by a custom servlet). When a URL such as this is stored as a URIType instance, it is
generally desirable to use subtype DBURIType, since this URI targets database data.
However, if a URIType instance is created using PL/SQL methods of package
URIFACTORY, then, by default, the subtype used is HTTPURIType, not DBURIType.
This is because URIFACTORY looks only at the URI prefix, sees http://, and assumes
that the URI targets a Web page. This results in unnecessary layers of communication
and perhaps extra character conversions.
To make things more efficient, you can teach URIFACTORY that URIs of the given form
represent database accesses and so should be realized as DBUris, not HTTPUris. You
do this by registering a handler for this URI as a prefix, specifying DBURIType as the
type of instance to generate.
Example 20–22 effectively tells URIFACTORY that any URI string starting with
http://server/servlets/oradb corresponds to a database access.
Example 20–22 Registering a Handler for a DBUri Prefix
BEGIN
URIFACTORY.registerURLHandler('http://server/servlets/oradb',
'SYS', 'DBURIType', true, true);
END;
/

After you execute this code, all getURI() calls in the same session automatically
create DBUris for any URI strings with prefix http://server/servlets/oradb.
Oracle Database PL/SQL Packages and Types Reference for
information about URIFACTORY functions

See Also:

Accessing Data Through URIs 20-29

DBUriServlet

20-30 Oracle XML DB Developer's Guide

Part V
Oracle XML DB Repository
Part V of this manual describes Oracle XML DB repository. It includes how to version
your data, implement and manage security, and how to use the associated Oracle
XML DB APIs to access and manipulate repository data.
Part V contains the following chapters:
■

Chapter 21, "Accessing Oracle XML DB Repository Data"

■

Chapter 22, "Configuring Oracle XML DB Repository"

■

Chapter 23, "Using XLink and XInclude with Oracle XML DB"

■

Chapter 24, "Managing Resource Versions"

■

Chapter 25, "Accessing the Repository using RESOURCE_VIEW and PATH_
VIEW"

■

Chapter 26, "Accessing the Repository using PL/SQL"

■

Chapter 27, "Repository Access Control"

■

Chapter 28, "Accessing the Repository using Protocols"

■

Chapter 29, "User-Defined Repository Metadata"

■

Chapter 30, "Oracle XML DB Repository Events"

■

Chapter 31, "Using Oracle XML DB Content Connector"

■

Chapter 32, "Writing Oracle XML DB Applications in Java"

■

Chapter 33, "Using Native Oracle XML DB Web Services"

21
Accessing Oracle XML DB Repository Data
This chapter describes how to access data in Oracle XML DB Repository using
standard protocols such as FTP and HTTP(S)/WebDAV, and other Oracle XML DB
resource Application Program Interfaces (APIs). It also introduces you to using
RESOURCE_VIEW and PATH_VIEW as the SQL mechanism for accessing and
manipulating repository data. It includes a table for comparing repository operations
through the various resource APIs.
This chapter contains these topics:
■

Overview of Oracle XML DB Repository

■

Repository Terminology and Supplied Resources

■

Oracle XML DB Repository Resources

■

Two Ways to Access Oracle XML DB Repository Resources

■

Navigational or Path Access to Repository Resources

■

Query-Based Access to Repository Resources

■

Servlet Access to Repository Resources

■

Operations on Repository Resources

Overview of Oracle XML DB Repository
Using Oracle XML DB Repository you can store content in the database in hierarchical
structures, as opposed to traditional relational database structures.
Figure 21–1 is an example of a hierarchical structure that shows a typical tree of folders
and files in Oracle XML DB Repository. The top of the tree shows /, the root folder.

Accessing Oracle XML DB Repository Data 21-1

Overview of Oracle XML DB Repository

Figure 21–1 A Folder Tree, Showing Hierarchical Structures in the Repository
/

Root Node

/home

/sys
Oracle XML DB System Folders
Do not store your data in /sys

/general

/log

/schemas

/PUBLIC

/schemas

/acls
/po

/acls

/XDB

/QUINE

/graphics

/schemas

/acls

Oracle
XML DB
folders
(containers)

/xmlns.oracle.com
Directories
(containers)

/xdb

Files or Documents
(non-containers)
architecture.jpg
logo.gif
banner.png
readme.txt
whatsnew.fm
into.doc
maincode.jav
chapter1.xml
po_101.xml
po_Jan02.xml
po_Jan03.xml

11_28_01.txt
Graphics
or
binary.files
stored in
BLOBs

Binary
files stored
as BLOBs

all_owner_acl.xml
all_all_acl.xml

XDBSchema.xsd

XML files
typically stored
object-relationally
can also store
in LOBS

ACL files
are stored
in xdb.xdb$ACL
table

XML files
stored in your
XMLType
tables / views

Folder /sys is used by Oracle XML DB to maintain
system-defined XML schemas, access control lists (ACLs), and so on.
Do not add or modify any data in folder /sys.

Note:

Foldering lets applications access hierarchically indexed content in the database using
the FTP, HTTP(S), and WebDAV protocol standards as if the database content were
stored in a file system. You can set access control privileges on repository folders and
resources.
This chapter provides an overview of how to access data in Oracle XML DB
Repository folders using the standard protocols. It discusses APIs that you can use to
access the repository object hierarchy using Java, SQL, and PL/SQL.
See Also:
■

Chapter 25, "Accessing the Repository using RESOURCE_
VIEW and PATH_VIEW"

■

Chapter 26, "Accessing the Repository using PL/SQL"

■

Chapter 27, "Repository Access Control"

■

Chapter 28, "Accessing the Repository using Protocols"

21-2 Oracle XML DB Developer's Guide

Repository Terminology and Supplied Resources

Two Ways to Access Oracle XML DB Repository Resources
There are two ways to access Oracle XML DB Repository resources:
■

Navigational or path-based access. This uses a hierarchical index of resources.
Each resource has one or more unique path names that reflect its location in the
hierarchy. You can navigate, using XPath expressions, to any repository resource.
A repository resource can be created as a reference to an existing XMLType object
in the database. You can navigate to any such database object using XPath. See
"Navigational or Path Access to Repository Resources" on page 21-9.

■

SQL access to the repository. This is done using special views that expose resource
properties and path names, and map hierarchical access operators onto the Oracle
XML DB schema. See "Query-Based Access to Repository Resources" on
page 21-13.
See Also:
■

■

"Oracle XML DB Repository Access" on page 2-3 for guidance
on selecting an access method
Table 21–3, " Accessing Oracle XML DB Repository: API
Options" for a summary comparison of the access methods

A Uniform Resource Locator (URL) is used to access an Oracle XML DB resource. A
URL includes the host name, protocol information, path name, and resource name of
the object.

Repository Terminology and Supplied Resources
Oracle XML DB Repository is the set of database objects, across all XML and database
schemas, that are mapped to path names. It is a connected, directed, acyclic1 graph of
resources, with a single root node (/). Each resource in the graph has one or more
associated path names: the repository supports multiple links to a given resource. The
repository can be thought of as a file system of objects rather than files.

Repository Terminology
The following list describes terms used in Oracle XML DB Repository:
■

resource – Any object or node in the repository hierarchy. Resources are identified
by URLs.
See Also:
"Overview of Oracle XML DB Repository" on page 1-7
"Oracle XML DB Repository Resources" on page 21-5

■
■

1

folder – A resource that can contain other resources. Sometimes called a directory.
path name – A hierarchical name representing an absolute path to a resource. It is
composed of a slash (/) representing the repository root, followed by zero or more
path components separated by slashes. A path component cannot be only . or ..,
but a period (.) can otherwise be used in a path component. A path component is
composed of any characters in the database character set except slash (/), backslash
The graph is established by the hard links that define the repository structure, and cycles are
not permitted using hard links. You can, however, introduce cycles using weak links. See
"Hard Links and Weak Links" on page 21-7.

Accessing Oracle XML DB Repository Data 21-3

Repository Terminology and Supplied Resources

(\), and those characters specified in the Oracle XML DB configuration file,
/xdbconfig.xml, by configuration parameter
/xdbconfig/sysconfig/invalid-pathname-chars.
■

■

■

■

resource name (or link name) – The name of a resource within its parent folder.
This is the rightmost path component of a path name. Resource names must be
unique within their immediately containing folder, and they are case-sensitive.
resource content – The body, or data, of a resource. This is what you get when you
treat the resource as a file and ask for its content. This is always of type XMLType.
XDBBinary element – An XML element that contains binary data. It is defined by
the Oracle XML DB XML schema. XDBBinary elements are stored in the
repository whenever unstructured binary data is uploaded into Oracle XML DB.
access control list (ACL) – A set of principals (users or roles) that are allowed
access to one or more specific resources.
See Also:

Chapter 27, "Repository Access Control"

Many terms used by Oracle XML DB have common synonyms in other contexts, as
shown in Table 21–1.
Table 21–1

Synonyms for Oracle XML DB Repository Terms

Synonym

Repository Term Usage

collection

folder

WebDAV

directory

folder

operating systems

privilege

privilege

permission

right

privilege

various

WebDAV folder

folder

Web folder

role

group

access control

revision

version

RCS, CVS

file system

repository

operating systems

hierarchy

repository

various

file

resource

operating systems

binding

link

WebDAV

Supplied Files and Folders
The list of supplied Oracle XML DB Repository files and folders is as follows. In
addition to using these, you can create your own folders and files wherever you want.
/public
/sys
/sys/acls
/sys/acls/all_all_acl.xml
/sys/acls/all_owner_acl.xml
/sys/acls/bootstrap_acl.xml
/sys/acls/ro_all_acl.xml
/sys/apps
/sys/asm
/sys/log
/sys/schemas
/sys/schemas/PUBLIC

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Oracle XML DB Repository Resources

/sys/schemas/PUBLIC/www.w3.org
/sys/schemas/PUBLIC/www.w3.org/2001
/sys/schemas/PUBLIC/www.w3.org/2001/xml.xsd
/sys/schemas/PUBLIC/xmlns.oracle.com
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/XDBFolderListing.xsd
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/XDBResource.xsd
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/XDBSchema.xsd
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/XDBStandard.xsd
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/acl.xsd
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/dav.xsd
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/log
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/log/ftplog.xsd
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/log/httplog.xsd
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/log/xdblog.xsd
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/stats.xsd
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/xdbconfig.xsd
/xdbconfig.xml

Oracle XML DB Repository Resources
Oracle XML DB Repository resources conform to the Oracle XML DB XML schema
XDBResource.xsd. The elements in a resource include those needed to persistently
store WebDAV-defined properties, such as creation date, modification date, WebDAV
locks, owner, ACL, language, and character set.
See Also: "XDBResource.xsd: XML Schema for Oracle XML DB
Resources" on page A-1

A resource index has a special element called Contents that contains the contents of
the resource.
The XML schema for a resource also defines an any element, with maxoccurs
attribute unbounded. An any element can contain any element outside of the Oracle
XML DB XML namespace. Arbitrary instance-defined properties can be associated
with the resource.

Where Is Repository Data Stored?
Oracle XML DB stores Oracle XML DB Repository data in a set of tables and indexes to
which you have access. If you register an XML schema and request that the tables be
generated by Oracle XML DB, then the tables are created in your database schema.
You are then able to see or modify them. Other users cannot see your tables unless you
grant them permission to do so.

Names of Generated Tables
The names of the generated tables are assigned by Oracle XML DB, and can be
obtained by finding the xdb:defaultTable attribute in your XML schema
document (or in the default XML schema document). When you register an XML
schema, you can alternatively provide your own table name, instead of using the
default name supplied by Oracle XML DB. If the table specifies binary XML storage,
then a document is encoded in binary XML format before storing it in the table.
See Also: "Default Tables Created During XML Schema
Registration" on page 7-10

Accessing Oracle XML DB Repository Data 21-5

Oracle XML DB Repository Resources

Defining Structured Storage for Resources
Applications that need to define structured storage for resources can do so in one of
these ways:
■

■

Subclass the Oracle XML DB resource type. Subclassing Oracle XML DB resources
requires privileges on the table XDB$RESOURCE.
Store data that conforms to a visible, registered XML schema.
See Also:

Chapter 7, "XML Schema Storage and Query: Basic"

Oracle ASM Virtual Folder
The Oracle Automatic Storage Management (Oracle ASM) virtual folder, /sys/asm, is
an exception to the description of the previous sections: its contents are Oracle ASM
files and folders that are managed automatically by Oracle ASM.
See Also:
■

■

"Accessing Oracle ASM Files using Protocols and Resource APIs –
For DBAs" on page 21-12
Oracle Automatic Storage Management Administrator's Guide

Path-Name Resolution
The data relating a folder to its contents is managed by the Oracle XML DB
hierarchical repository index. This provides a fast mechanism for evaluating path
names, similar to the directory mechanisms that are used by operating-system file
systems.
Resources that are folders have the Container attribute of element Resource set to
true.
To resolve a resource name in a folder, the current user must have the following
privileges:
■

resolve privilege on the folder

■

read-properties on the resource in that folder

If the user does not have these privileges, then the user receives an access denied
error. Folder listings and other queries do not return a row when the
read-properties privilege is denied on its resource.
Caution: Error handling in path-name resolution differentiates
between invalid resource names and resources that are not folders,
for compatibility with file systems. Because Oracle XML DB
resources are accessible from outside Oracle XML DB Repository
(using SQL), denying read access on a folder that contains a
resource does not prevent read access to that resource.

See Also: "XDBResource.xsd: XML Schema for Oracle XML DB
Resources" on page A-1 for the definition of element Resource and
its attribute Container

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Oracle XML DB Repository Resources

Link Types
Links in Oracle XML DB can be repository links or document links. Repository links
can be hard links or weak links. Document links can also be hard links or weak links,
when their targets are repository resources. These terms are explained further in the
following sections.

Repository and Document Links
In addition to containing resources, a folder resource can contain links to other
resources (files or folders). These repository links, sometimes called folder links, are
not to be confused with document links, which correspond to the links provided by
the XLink and XInclude standards, and which are also supported by Oracle XML DB.
Repository links are navigational, folder–child links among repository resources.
Document links are arbitrary links among documents that are not necessarily
repository resources.
Repository links represent repository hierarchical relationships. Document links
represent arbitrary relationships whose semantics derives from the applications that
use them. Because they represent repository hierarchical relationships, repository links
can be navigated using file system-related protocols. This is not true of document
links. Because document links can represent arbitrary relationships, they can also
represent repository relationships. When document links thus target resources, they
can also be hard or weak.
See Also: Chapter 23, "Using XLink and XInclude with Oracle
XML DB" for information about document links

Hard Links and Weak Links
Links that target repository resources can be hard links or weak links. Both hard and
weak links are references, or pointers, to physical data—(internal) repository resource
identifiers. They do not point to symbolic names or paths to other links. Their targets
are resolved at the time of link creation. Because they point directly to resource
identifiers, hard and weak links cannot dangle: they remain valid even when their
targets are renamed or moved. You need the same privileges to create or delete hard
and weak links.
The difference between hard and weak links lies in their relationship to target resource
deletion. A target resource is dependent on its hard links, in the sense that it cannot be
deleted as long as it remains the target of a hard link. Deletion of a hard link also
deletes the resource targeted by the link, if the following are both true:
■
■

The resource is not versioned.
The hard link that was deleted was the last (that is, the only) hard link to the
resource.

A weak link has no such hold on a resource: you can delete a resource, even if it is the
target of a weak link (as long as it is not the target of a hard link). Because of this, weak
links can be used as shortcuts to frequently accessed resources, without impacting
deletion of those resources.
There is a dependency in the other direction, however: If you delete a resource that is
the target of one or more weak links, then those links are automatically deleted, as
well. In this sense, too, weak links cannot dangle. Both hard and weak links provide
referential integrity: if a link exists, then so does its target.
Another difference between hard and weak links is this: Hard links to ancestor folders
are not permitted, because they introduce cycles. There is no such restriction for weak

Accessing Oracle XML DB Repository Data 21-7

Oracle XML DB Repository Resources

links: a weak link can target any folder, possibly creating a cycle. It is the set of hard
links that define the (acyclic) structure of Oracle XML DB Repository. Weak links
represent an additional mapping on top of that basic structure.
You can query the repository path view, PATH_VIEW, to determine the type of a
repository link: the link information contains the link type. XMLType column LINK of
PATH_VIEW contains this information in element LinkType, which is a child of the
root element, LINK. Example 21–1 illustrates this. You can also determine the type of a
repository link by using the getLink() callback function on an event handler
(LinkIn, LinkTo, UnlinkIn, or UnlinkFrom).
Example 21–1

Querying PATH_VIEW to Determine Link Type

SELECT RESID, XMLCast(XMLQuery('/LINK/LinkType' PASSING LINK RETURNING CONTENT)
AS VARCHAR2(24)) link_type
FROM PATH_VIEW WHERE equals_path(RES, '/home/QUINE/purchaseOrder.xml') = 1;
RESID
-------------------------------DF9856CF2FE0829EE030578CCE0639C5

LINK_TYPE
--------Weak

See Also:
■
■

■

"Deleting Repository Resources: Examples" on page 25-14
"Query-Based Access to Repository Resources" on page 21-13
for information about PATH_VIEW
Oracle Database PL/SQL Packages and Types Reference for
information on PL/SQL function getLink

Creating a Weak Link with No Knowledge of Folder Hierarchy
Suppose that you want to read a file resource that belongs to one of your colleagues.
You cannot create a hard link to that resource, to make it accessible for your use, unless
you have the privilege  on all of the ancestor folders of that file.
Having that privilege would mean that you could see all of your colleague's folder
names and the structure of the hierarchy down to the target resource.
However, because weak links essentially represent a mapping on top of the real
repository structure, which structure is determined by the set of hard links, you can
create a weak link to a resource using just its OID rather than its full, named path
(URL). Your colleague can determine the OID path to the file, send you that instead of
the named path, and you can create a weak link to the document using that OID path.
Example 21–2 and Example 21–3 illustrate this.
Example 21–2 prints the OID path for the file resource
/home/QUINE/purchaseOrder.xml. User quine can use this to obtain the OID
path to the resource, and then send that path to user curry, who can create a weak
link to the resource (Example 21–3).
Example 21–2

Obtaining the OID Path of a Resource

DECLARE
resoid RAW(16);
oidpath VARCHAR2(100);
BEGIN
SELECT RESID INTO :resoid FROM RESOURCE_VIEW
WHERE equals_path(RES, '/home/QUINE/purchaseOrder.xml') = 1;
oidpath := DBMS_XDB.createOIDPath(resoid)
DBMS_OUTPUT.put_line(oidpath);

21-8 Oracle XML DB Developer's Guide

Navigational or Path Access to Repository Resources

END;

In Example 21–3, user curry creates a weak link named quinePurchaseOrder.xml
in folder /home/CURRY. The target of the link is the OID path that corresponds to the
URL /home/QUINE/purchaseOrder.xml. User curry need not be aware of the
repository structure that is visible to user quine.
Example 21–3

Creating a Weak Link using an OID Path

CALL DBMS_XDB.Link(/sys/oid/1BDCB46477B59C20E040578CCE0623D3
'/home/CURRY', 'quinePurchaseOrder.xml',
DBMS_XDB.LINK_TYPE_WEAK);

Restricting Multiple Hard Links
Sometimes, it is useful to restrict the creation of hard links, disallowing multiple hard
links to folders or files (or both). In particular, allowing multiple hard links to file
resources, but disallowing multiple hard links to folder resources, provides behavior
that is similar to that for some file systems, including UNIX and Linux. This can
simplify application design, by, in effect, ensuring that each file resource has a unique,
canonical hard-link path to it. In addition, preventing multiple hard links to a resource
can lead to query performance improvements.
You can configure the prevention of multiple hard links using the following Boolean
parameters in configuration file xdbconfig.xml. The default value of each
parameter is true, meaning that multiple hard links can be created.
■

■

folder-hard-links – Prevent the creation of multiple hard links to a folder
resource, if false.
non-folder-hard-links – Prevent the creation of multiple hard links to a file
resource, if false.
See Also: "Configuring Oracle XML DB using xdbconfig.xml" on
page 34-5

Navigational or Path Access to Repository Resources
Oracle XML DB Repository folders support the same protocol standards used by many
operating systems. This lets a repository folder act like a native folder (directory) in
supported operating-system environments. For example, you can:
■

■

Use Windows Explorer to open and access Oracle XML DB folders and resources
the same way you access other directories or resources in the Windows NT file
system, as shown in Figure 21–2.
Access Oracle XML DB Repository data using HTTP(S)/WebDAV from an Internet
Explorer browser, such as when viewing Web Folders, as shown in Figure 21–3.
Figure 21–3 shows a Web browser visiting URL http://xdbdemo:8080/: the
server it is connected to is xdbdemo, and its HTTP port number is 8080.
See Also: "Configuring Protocol Server Parameters" on page 28-3 for
information about configuring the HTTP port number

Accessing Oracle XML DB Repository Data 21-9

Navigational or Path Access to Repository Resources

Figure 21–2 Oracle XML DB Folders in Windows Explorer

Figure 21–3 Accessing Repository Data using HTTP(S)/WebDAV and Navigational
Access From IE Browser: Viewing Web Folders

Accessing Oracle XML DB Resources using Internet Protocols
Oracle Net Services provides one way of accessing database resources. Oracle XML DB
support for Internet protocols provides another way of accessing database resources.

21-10 Oracle XML DB Developer's Guide

Navigational or Path Access to Repository Resources

Where You Can Use Oracle XML DB Protocol Access
Oracle Net Services is optimized for record-oriented data. Internet protocols are
designed for stream-oriented data, such as binary files or XML text documents. Oracle
XML DB protocol access is a valuable alternative to Net Services in the following
scenarios:
■

■

■
■

Direct database access from file-oriented applications using the database like a file
system
Heterogeneous application server environments that require a uniform data access
method (such as XML over HTTP, which is supported by most data servers,
including MS SQL Server, Exchange, Notes, many XML databases, stock quote
services and news feeds)
Application server environments that require data in the form of XML text
Web applications that use client-side XSL to format datagrams that do not need
much application processing

■

Web applications that use Java servlets that run inside the database

■

Web access to XML-oriented stored procedures

Using Protocol Access
Accessing Oracle XML DB using a protocol proceeds as follows:
1.

A connection object is established, and the protocol might read part of the request.

2.

The protocol decides whether the user is already authenticated and wants to reuse
an existing session or the connection must be re-authenticated (the latter is more
common).

3.

An existing session is pulled from the session pool, or else a new one is created.

4.

If authentication has not been provided, and the request is HTTP get or head,
then the session is run as the ANONYMOUS user. If the session has already been
authenticated as the ANONYMOUS user, then there is no cost to reuse the existing
session. If authentication has been provided, then the database re-authentication
routines are used to authenticate the connection.

5.

The request is parsed.

6.

(HTTP only) If the requested path name maps to a servlet, then the servlet is
invoked using Java Virtual Machine (VM). The servlet code writes the response to
a response stream or asks XMLType instances to do so.

Retrieving Oracle XML DB Resources
When the protocol indicates that a resource is to be retrieved, the path name to the
resource is resolved. Resources being fetched are always streamed out as XML, with
the exception of resources containing the XDBBinary element, an element defined to
be the XML binary data type, which have their contents streamed out in RAW form.

Storing Oracle XML DB Resources
When the protocol indicates that a resource must be stored, Oracle XML DB checks the
document file name extension for .xml, .xsl, .xsd, and so on. If the document is
XML, then a pre-parse step is done, whereby enough of the resource is read to
determine the XML schemaLocation and namespace of the root element in the
document. If a registered schema is located at the schemaLocation URL, and it has a

Accessing Oracle XML DB Repository Data 21-11

Navigational or Path Access to Repository Resources

definition for the root element of the current document, then the default table specified
for that root element is used to store the contents of the resource.

Using Internet Protocols and XMLType: XMLType Direct Stream Write
Oracle XML DB supports Internet protocols at the XMLType level by using Java
XMLType method writeToStream(). This method is implemented natively and
writes XMLType data directly to the protocol request stream. This avoids Java VM
execution costs and the overhead of converting database data through Java data types
and creating Java objects, resulting in significantly higher performance. Performance is
further enhanced if the Java code deals only with XML element trees that are close to
the root, and does not traverse too many of the leaf elements, so that relatively few
Java objects are created.
See Also:

Chapter 28, "Accessing the Repository using Protocols"

Accessing Oracle ASM Files using Protocols and Resource APIs – For DBAs
Oracle Automatic Storage Management (Oracle ASM) organizes database files into disk
groups for simplified management and added benefits such as database mirroring and
I/O balancing.
Repository access using protocols and resource APIs (such as DBMS_XDB) extends to
Oracle ASM files. These files are accessed in the virtual repository folder /sys/asm.
However, this access is reserved for database administrators (DBAs). It is not intended
for developers.
A typical use of such access is to copy Oracle ASM files from one database instance to
another. For example, a DBA can view folder /sys/asm in a graphical user interface
using the WebDAV protocol, and then drag-and-drop a copy of a data-pump dump set
from an Oracle ASM disk group to an operating-system file system.
Virtual folder /sys/asm is created by default during Oracle XML DB installation. If
the database is not configured to use Oracle ASM, the folder is empty and no
operations are permitted on it.
Folder /sys/asm contains folders and subfolders that follow the hierarchy defined by
the structure of an Oracle ASM fully qualified filename:
■
■

It contains a subfolder for each mounted disk group.
A disk-group folder contains a subfolder for each database that uses that disk
group. In addition, a disk-group folder may contain files and folders
corresponding to Oracle ASM aliases created by the administrator.

■

A database folder contains file-type folders.

■

A file-type folder contains Oracle ASM files, which are binary.

This hierarchy is shown in Figure 21–4, which omits directories created for aliases, for
simplicity.

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Query-Based Access to Repository Resources

Figure 21–4 Oracle ASM Virtual Folder Hierarchy

/sys/asm
Disk Groups

DATA

RECOVERY

Databases

HR

MFG

HR

MFG

File
Types
DATAFILE

TEMPFILE

CONTROLFILE

ONLINELOG

CONTROLFILE ONLINELOG

ARCHIVELOG

The following usage restrictions apply to virtual folder /sys/asm. You cannot:
■

query /sys/asm using SQL

■

put regular files under /sys/asm (you can put only Oracle ASM files there)

■

■

move (rename) an Oracle ASM file to a different Oracle ASM disk group or to a
folder outside Oracle ASM
create hard links to existing Oracle ASM files or directories

In addition:
■
■

You must have the privileges of role DBA to view folder /sys/asm.
To access /sys/asm using Oracle XML DB protocols, you must log in as a user
other than SYS.

Again, Oracle ASM virtual-folder operations are intended only for database
administrators, not developers.
See Also:
■

■

"Using FTP with Oracle ASM Files" on page 28-11 for an example
of using protocol FTP with /sys/asm
Oracle Automatic Storage Management Administrator's Guide for
information about the syntax of a fully qualified Oracle ASM
filename and details on the virtual folder structure

Query-Based Access to Repository Resources
There are two views that enable SQL access to Oracle XML DB Repository data:
■

PATH_VIEW

Accessing Oracle XML DB Repository Data 21-13

Servlet Access to Repository Resources

■

RESOURCE_VIEW

Table 21–2 summarizes the differences between PATH_VIEW and RESOURCE_VIEW.
Table 21–2

Differences Between PATH_VIEW and RESOURCE_VIEW

PATH_VIEW

RESOURCE_VIEW

Contains link properties

No link properties

Has one row for each unique path in repository Has one row for each resource in repository

Rows in these two repository views are of XMLType. In the RESOURCE_VIEW, the
single path associated with a resource is arbitrarily chosen from among the possible
paths that refer to the resource. Oracle XML DB provides SQL functions, such as
under_path, that let applications search for the resources contained within a
particular folder (recursively), obtain the resource depth, and so on.
DML can be used on the repository views to insert, rename, delete, and update
resource properties and contents. Programmatic APIs must be used for other
operations, such as creating links to existing resources.
See Also:
■

■

Chapter 25, "Accessing the Repository using RESOURCE_
VIEW and PATH_VIEW" for details on SQL access to Oracle
XML DB Repository
Chapter 27, "Repository Access Control"

Servlet Access to Repository Resources
Oracle XML DB implements Java Servlet API, version 2.2, with the following
exceptions:
■

■

■

All servlets must be distributable. They must expect to run in different virtual
machines.
WAR and web.xml files are not supported. Oracle XML DB supports a subset of
the XML configurations in this file. An XSL style sheet can be applied to the
web.xml to generate servlet definitions. An external tool must be used to create
database roles for those defined in the web.xml file.
JSP (Java Server Pages) support can be installed as a servlet and configured
manually.

■

HTTPSession and related classes are not supported.

■

Only one servlet context (that is, one Web application) is supported.
See Also: Chapter 32, "Writing Oracle XML DB Applications in
Java"

Operations on Repository Resources
You can operate on data stored in Oracle XML DB Repository resources using any of
the following:
■
■

Oracle XML DB resource APIs for Java
A combination of Oracle XML DB resource views API and Oracle XML DB
resource API for PL/SQL

21-14 Oracle XML DB Developer's Guide

Operations on Repository Resources

■

■

Internet protocols (HTTP(S)/WebDAV and FTP) and Oracle XML DB protocol
server
Oracle XML DB Content Connector and, through it, the standard Content
Repository API for Java (JCR).

These access methods can be used equivalently. It does not matter how you add
content to the repository or retrieve it from there. For example, you can add content to
the repository using SQL or PL/SQL and then retrieve it using an Internet protocol,or
the other way around.
Table 21–3 lists common Oracle XML DB Repository operations, and describes how
these operations can be accomplished using each of several access methods. The table
shows functionality common to the different methods, but not all of the methods are
equally suited to any particular task. Unless mentioned otherwise, "resource" in this
table can be either a file resource or a folder resource.
Table 21–3 also shows the resource privileges that are required for each operation. In
addition to the privileges listed in the table, privilege xdb:read-properties is
required on each resource affected by an operation. Operations that affect the parent
folder of a resource, in addition to the resource targeted by the operation, also require
privilege xdb:read-properties on that parent folder. For example, deleting a
resource affects both the resource to delete and its parent folder, so you need privilege
xdb:read-properties on both the resource and its parent folder.

Table 21–3

Accessing Oracle XML DB Repository: API Options

Data Access

SQL and PL/SQL

Protocols

Create
resource

DBMS_XDB.createResource('/public/T1/testcase.txt',
'ORIGINAL text');
INSERT INTO RESOURCE_VIEW (ANY_PATH, RES)
SELECT '/public/T1/copy1.txt', RES
FROM RESOURCE_VIEW
WHERE equals_path(RES,
'/public/T1/testcase.txt')
= 1;

HTTP:PUT DAV::bind on parent folder Yes
;

Update
resource
contents

UPDATE RESOURCE_VIEW
SET RES =
updateXML(
RES,
'/Resource/Contents/text/text()',
'NEW text',
'xmlns =
"http://xmlns.oracle.com/xdb/XDBResource.xsd')
WHERE equals_path(RES,
'/public/T1/copy1.txt') = 1;

HTTP:
PUT;

Update
resource
properties

UPDATE RESOURCE_VIEW
SET RES =
updateXML(
RES,
'/Resource/DisplayName/text()',
'NewName1.txt',
'xmlns =
"http://xmlns.oracle.com/xdb/XDBResource.xsd')
WHERE equals_path(RES,
'/public/T1/copy1.txt') = 1;

WebDAV:

Update
resource ACL

EXEC DBMS_XDB.setACL(
'/public/T1/copy1.txt',
'/sys/acls/all_owner_acl.xml');

not
applicable

Resource Privileges
Required

JCR
Support

FTP: PUT

xdb:write-content on
resource

Yes

FTP: PUT

DAV::write-properties Yes
PROPPATC on resource
H;

DAV::write-acl on
resource

No

Accessing Oracle XML DB Repository Data 21-15

Operations on Repository Resources

Table 21–3 (Cont.) Accessing Oracle XML DB Repository: API Options
Resource Privileges
Required

JCR
Support
Yes

DELETE;

DAV::unbind on parent
folder

FTP:
delete

xdb:unlink-from on
resource

Data Access

SQL and PL/SQL

Protocols

Unlink
resource
(delete if last
link)

EXEC DBMS_XDB.deleteResource()
DELETE FROM RESOURCE_VIEW
WHERE equals_path(RES, path) > 0

HTTP:

Forcibly
remove all
links to
resource

DBMS_XDB.deleteResource()
DELETE FROM PATH_VIEW
WHERE
XMLCast(
XMLQuery(
'declare namespace n1=
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
//n1:DisplayName'
PASSING RES RETURNING CONTENT)
AS VARCHAR2(256))
= 'My resource'

FTP:

UPDATE PATH_VIEW
SET path = '/public/T1/copy2.txt'
WHERE equals_path(RES,
'/public/T1/copy1.txt')
= 1;

WebDAV:

Move
resource

Copy resource INSERT INTO PATH_VIEW (path, RES, link)
SELECT '/public/T1/copy3.txt', RES, link
FROM PATH_VIEW
WHERE equals_path(RES,
'/public/T1/copy2.txt')
= 1;

quote
rm_rf

DAV::unbind on all parent
folders

Yes

xdb:unlink-from on
resource

resource

MOVE;

DAV::unbind on source
parent folder

FTP:
rename

DAV::bind on target parent
folder

Yes

xdb:unlink-from and
xdb:link-to on resource
WebDAV:

Copy to new:

COPY;

DAV::bind on target parent
folder

Yes

DAV::read on resource
Copy to existing
(replacement):
DAV::read on resource
DAV::write-properties
and DAV::write-content
on existing target resource

Create hard
link to
existing
resource

EXEC DBMS_XDB.link('/public/T1/copy3.txt',
'/public/T1',
'myhardlink');

not
applicable

DAV::bind on parent folder No

Create weak
link to
existing
resource

EXEC DBMS_XDB.link('/public/T1/copy3.txt',
'/public/T1',
'myweaklink',
DBMS_XDB.LINK_TYPE_WEAK);

not
applicable

DAV::bind on parent folder No

Change
owner of
resource

UPDATE RESOURCE_VIEW
SET RES =
updateXML(
RES,
'/Resource/Owner/text()',
'U2')
WHERE equals_path(RES, '/public/T1/copy3.txt')
= 1;

not
applicable

DAV::take-ownership on Yes
resource

21-16 Oracle XML DB Developer's Guide

xdb:link-to on resource

xdb:link-to on resource

Operations on Repository Resources

Table 21–3 (Cont.) Accessing Oracle XML DB Repository: API Options
Resource Privileges
Required

JCR
Support

Get binary or SELECT XDBURIType(path).getBLOB()
HTTP:
text
GET;
FROM DUAL;
representation
FTP: get
of resource
SELECT
contents
XMLQuery(
'declare default element namespace
"http://xmlns.oracle.com/xdb/XDBResource.xsd";(: :)
$r/Resource/Contents'
PASSING RES AS "r" RETURNING CONTENT)
FROM RESOURCE_VIEW
WHERE equals_path(RES, '/public/T1/copy2.text') = 1;

xdb:read-contents on
resource

Yes

Get XMLType SELECT XDBURIType('/public/T1/res.xml').getXML
representation
FROM DUAL;
of resource
contents
SELECT
XMLQuery(
'declare default element namespace
"http://xmlns.oracle.com/xdb/XDBResource.xsd";(: :)
$r/Resource/Contents/*'
PASSING RES AS "r" RETURNING CONTENT)
FROM RESOURCE_VIEW
WHERE equals_path(RES, '/public/T1/res.xml') = 1;

not
applicable

xdb:read-contents on
resource

No

Get resource
properties

SELECT
XMLCast(
XMLQuery(
'declare default element namespace
"http://xmlns.oracle.com/xdb/XDBResource.xsd";(: :)
$r/Resource/LastModifier'
PASSING RES AS "r" RETURNING CONTENT)
AS VARCHAR2(128))
FROM RESOURCE_VIEW
WHERE equals_path(RES, '/public/T1/res.xml') = 1;

WebDAV:

xdb:read-properties on Yes
resource

SELECT PATH FROM PATH_VIEW
WHERE under_path(res, '/public/T1') = 1;

WebDAV:

Data Access

List resources
in folder

SQL and PL/SQL

Protocols

PROPFIND
(depth =
0);

PROPFIND

xdb:read-contents on
folder

Yes

(depth =
0);
Create folder

Call DBMS_XDB.createFolder('/public/T2');

WebDAV:

DAV::bind on parent folder Yes

MKCOL;
FTP:
mkdir
Unlink empty DBMS_XDB.deleteResource('/public/T2')
folder

HTTP:
DELETE;

DAV::unbind on parent
folder

FTP:
rmdir

xdb:unlink-from on
resource
DAV::unbind on all parent
folders

Yes

Forcibly
delete folder
and all links
to it

DBMS_XDB.deleteResource(
'/public/T2',
DBMS_XDB.DELETE-RECURSIVE_FORCE);

not
applicable

Get resource
with a row
lock

SELECT ...
FROM RESOURCE_VIEW
FOR UPDATE ...;

not
applicable

xdb:read-properties
and xdb:read-contents
on resource

WebDAV:

DAV::write-properties No
on resource

Add WebDAV EXEC DBMS_XDB.LockResource('/public/T1/res.xml',
lock on
TRUE,
resource
TRUE);

Yes

xdb:unlink-from on
folder resource

LOCK;

No

FTP:
quote
lock

Accessing Oracle XML DB Repository Data 21-17

Operations on Repository Resources

Table 21–3 (Cont.) Accessing Oracle XML DB Repository: API Options
Data Access

SQL and PL/SQL

Protocols

Resource Privileges
Required

JCR
Support

Remove
DECLARE...
WebDAV lock BEGIN
DBMS_XDB.GetLockToken('/public/T1/res.xml',
locktoken);
DBMS_XDB.UnlockResource('/public/T1/res.xml',
locktoken);
END;

WebDAV:
UNLOCK;

Check out file
resource

EXEC DBMS_XDB_VERSION.checkOut(
'/public/T1/res.xml');

not
applicable

DAV::write-properties No
on resource

Check in file
resource

EXEC DBMS_XDB_VERSION.checkIn(
'/public/T1/res.xml');

not
applicable

DAV::write-properties No
on resource

Uncheck out
file resource

EXEC DBMS_XDB_VERSION.unCheckOut(
'/public/T1/res.xml');

not
applicable

DAV::write-properties No
on resource

Make file
resource
versioned

EXEC DBMS_XDB_VERSION.makeVersioned(
'/public/T1/res.xml');

not
applicable

DAV::write-properties No
on resource

Remove an
event handler

DBMS_XEVENT.remove

not
applicable

xdb:write-config on
resource or parent folder
(depending on the context)

Commit
changes

COMMIT;

Automatic not applicable
commit
after each
request

Yes

Rollback
changes

ROLLBACK;

not
applicable

Yes

FTP:

DAV::write-properties No
and DAV::unlock on
resource

quote
unlock

not applicable

See Also:
■

Chapter 25, "Accessing the Repository using RESOURCE_
VIEW and PATH_VIEW"

■

Chapter 26, "Accessing the Repository using PL/SQL"

■

Chapter 28, "Accessing the Repository using Protocols"

■

Chapter 31, "Using Oracle XML DB Content Connector"

■

■

■

Oracle Database PL/SQL Packages and Types Reference for
information about PL/SQL package DBMS_XDB
Oracle Database PL/SQL Packages and Types Reference for
information about PL/SQL package DBMS_XDB_VERSION
Oracle Database PL/SQL Packages and Types Reference for
information about PL/SQL package DBMS_XEVENT

21-18 Oracle XML DB Developer's Guide

No

22
Configuring Oracle XML DB Repository
This chapter describes how to configure Oracle XML DB Repository. It contains these
topics:
■

Resource Configuration Files Configure a Resource

■

Configuring a Resource

■

Common Configuration Parameters

This chapter describes general configuration that applies to all repository resources. It
does not describe configuration parameters for specific uses of resources. In particular,
it does not describe configuration parameters for handling events or managing XLink
and XInclude processing.
See Also:
■

"Configuring Repository Events" on page 30-8

■

Configuring Resources for XLink and XInclude on page 23-9

■

■

XDBResource.xsd: XML Schema for Oracle XML DB Resources on
page A-1
XDBResConfig.xsd: XML Schema for Resource Configuration on
page A-9

Resource Configuration Files Configure a Resource
Resource configuration is a general mechanism that you can use for events, mime-type
mappings, servlet parameters, XLink and XInclude processing, default ACL
specifications, and more.
You configure a Oracle XML DB Repository resource for any purpose by associating it
with a resource configuration file, which defines configurable parameters for the
resource. A resource configuration file is an XML file that conforms to the XML
schema XDBResConfig.xsd, which is accessible in Oracle XML DB Repository at
path /sys/schemas/PUBLIC/xmlns.oracle.com/xdb/XDBResConfig.xsd.
This XML schema is defined by Oracle XML DB, and you cannot alter it.
A resource configuration file is itself a resource in Oracle XML DB Repository. You use
PL/SQL procedure DBMS_RESCONFIG.addResConfig to map a resource to the file
that configures it. A single resource configuration file can alternatively apply to all
resources in the repository. In that case, you use PL/SQL procedure DBMS_
RESCONFIG.addRepositoryResConfig to map it to the repository as a whole.
The same resource configuration file can be used to configure more than one resource,
if appropriate. Oracle recommends that you have resources share a configuration file

Configuring Oracle XML DB Repository 22-1

Configuring a Resource

this way whenever the same configuration makes sense. This can improve run-time
performance. It also simplifies repository management by letting you update a
configuration in a single place and have the change affect multiple resources.
Avoid creating multiple, equivalent resource configuration files, because that can
impact performance negatively. If Oracle XML DB detects duplicate resource
configuration files, it raises an error.
Typically, you configure a resource for use with a particular application. In order for a
resource to be shared by multiple applications, it must be possible for different
applications to configure it differently. You do this by creating multiple resource
configuration files and mapping them to the same resource. Each resource is thus
associated with a list of configurations, a resource configuration list. Configurations
in a configuration list are processed in the list order.
The repository itself has a list of resource configuration files, for repository-wide
configuration, which really means configuration of all resources in the repository. The
same configuration file must not be used for both the repository itself and a specific
resource. Otherwise, an error is raised. An error is also raised if the same resource
configuration file appears more than once in any given resource configuration list.
An error is raised if you try to create more than 125 resource
configuration files for repository-wide configuration.

Note:

The resource configuration list of a new resource is based on the information in the
configuration elements of all resource configuration files for the parent folder of
the new resource. If there is no such information (no configuration file or no
defaultChildConfig elements in the files), then the configuration elements of
the repository resource configuration list are used. If that information is also missing,
then the new resource has an empty resource configuration list.
You can view the configuration list for a particular resource by extracting element
/Resource/RCList from column RES of view RESOURCE_VIEW, or by using
PL/SQL procedure DBMS_RESCONFIG.getResConfigPath. You can view the
configuration list for the repository as a whole by using PL/SQL procedure DBMS_
RESCONFIG.getRepositoryResConfigPath. To modify the repository-wide
configuration list, you must be granted role XDBADMIN.
See Also:

"Configuration Element defaultChildConfig" on page 22-3

Configuring a Resource
Follow these steps to configure an Oracle XML DB Repository resource or the
repository as a whole (all resources):
1.

Create a resource configuration file that defines the configuration. This XML file
must conform to XML schema XDBResConfig.xsd.

2.

Add the resource configuration file to the repository as a resource in its own right:
a configuration resource. You can use PL/SQL function DBMS_
XDB.createResource to do this.

3.

Map this configuration resource to the resources that it configures, or to the
repository if it applies to all resources. Use PL/SQL procedure DBMS_
RESCONFIG.addResConfig or DBMS_RESCONFIG.appendResConfig to map
an individual resource. Use DBMS_RESCONFIG.addRepositoryResConfig to
map the repository as a whole.

22-2 Oracle XML DB Developer's Guide

Common Configuration Parameters

4.

Commit.
Before performing any operation that uses a resource
configuration file, you must perform a COMMIT operation. Until you
do that, an ORA-22881 "dangling REF" error is raised whenever you
use the configuration file.

Note:

PL/SQL package DBMS_RESCONFIG provides additional procedures to delete a
configuration from a configuration list, obtain a list of paths to configurations in a
configuration list, and more.
If you delete a resource configuration file that is referenced by
another resource, a dangling REF error is raised whenever an attempt
is made to access the configured resource.

Note:

See Also:
■

■

■

■

Example 22–1 for an example of a simple resource configuration
file
"Configuring Repository Events" on page 30-8 for complete
examples of configuring resources
"XDBResConfig.xsd: XML Schema for Resource Configuration" on
page A-9
Oracle Database PL/SQL Packages and Types Reference for
information about package DBMS_RESCONFIG

Common Configuration Parameters
This section describes commonly used configuration parameters, that is, elements in a
configuration file. Parameters specific to particular types of configuration are
described elsewhere.

Configuration Element ResConfig
The top-level element of a resource configuration file is ResConfig. Besides
namespace and schemaLocation attributes, it can contain an optional enable
attribute. Set the value of attribute enable to false to disable the resource
configuration file, so that it has no effect on the resources mapped to it. This can be
useful for debugging or disabling an application. The default value of enable, used if
the attribute is not present, is true.

Configuration Element defaultChildConfig
This configuration element applies to folders only. It holds configuration information
that you want to be applied to all child resources in the folder. Element
defaultChildConfig has one or more configuration child elements, each of
which defines a possible configuration for resources in the folder.
A configuration element has the following child elements:
■

pre-condition (optional) – This element specifies a condition that must be met
before the resource configuration identified by the path element (see next) can be

Configuring Oracle XML DB Repository 22-3

Common Configuration Parameters

used as the default configuration. If element pre-condition is absent, then the
resource configuration file targeted by path applies to all resources in the folder.
That is, the precondition is treated as true.
A pre-condition element has an optional existsNode child element. An
existsNode element has a required XPath child element and an optional
namespace child element, both strings. These define an XPath 1.0 expression and
a namespace, respectively, that are used to check the existence of a resource. If that
resource exists, then the precondition is satisfied, so the resource configuration file
identified by path is used as a default resource configuration file for all child
resources in the folder. The first component of the XPath element must be
Resource.
A complex XPath expression for element XPath can impact
performance negatively.

Note:

If multiple configuration elements have true preconditions, then each of the
resource configuration files identified by their associated path elements applies to
all of the resources in the folder.
■

path (required) – This element specifies an absolute repository path to a resource
configuration file that is to be used as the default configuration for a new resource
whenever the precondition specified by element pre-condition is satisfied.

Typically, the value of the path element is a path to the current resource configuration
file, that is, the file that contains the path element. Example 22–1 illustrates this,
assuming that the resource configuration file is located at path /cm/app_rc.xml in
the repository. In this example, the precondition is that there be a Resource node
whose content is of type xml. When that precondition is met, the resource
configuration file in Example 22–1 applies to all resources in same folder as the
configuration file (/cm/app_rc.xml).
Example 22–1

Resource Configuration File






/Resource[ContentType="xml"]


/cm/app_rc.xml




Configuration Element applicationData
You use element applicationData to store application-specific data. An application
typically passes this data to an event handler when the handler is run. You can use any
XML content that you want inside element applicationData. An event handler
uses PL/SQL function DBMS_XEVENT.getApplicationData or Java function

22-4 Oracle XML DB Developer's Guide

Common Configuration Parameters

oracle.xdb.XMLType.getApplicationData to access the data in the
applicationData of the resource configuration file for the event listener.
Example 22–2 shows an applicationData element for use with an Oracle Spatial
application.
Example 22–2

applicationData Element



5
10



See Also:
■

■

■

Oracle Database PL/SQL Packages and Types Reference for
information about PL/SQL function DBMS_
XEVENT.getApplicationData
Oracle Database XML Java API Reference, class
XDBRepositoryEvent for information about Java function
oracle.xdb.XMLType.getApplicationData
Example 30–1, "Resource Configuration File for Java Event
Listeners with Preconditions" on page 30-9 for an example of a
resource configuration file for event listeners

Configuring Oracle XML DB Repository 22-5

Common Configuration Parameters

22-6 Oracle XML DB Developer's Guide

23
Using XLink and XInclude with Oracle
XML DB
This chapter describes how to use XLink and XInclude with resources in Oracle
XML DB Repository. It contains these topics:
■

Overview of XLink and XInclude

■

XLink and XInclude Link Types

■

XInclude: Compound Documents

■

Using XLink with Oracle XML DB

■

Using XInclude with Oracle XML DB

■

Examining XLink and XInclude Links using DOCUMENT_LINKS View

■

Configuring Resources for XLink and XInclude

■

Managing XLink and XInclude Links using DBMS_XDB.processLinks

Overview of XLink and XInclude
A document-oriented, or content-management, application often tracks relationships,
between documents, and those relationships are often represented and manipulated as
links of various kinds. Such links can affect application behavior in various ways,
including affecting the document content and the response to user operations such as
mouse clicks.
W3C has two recommendations that are pertinent in this context, for documents that
are managed in XML repositories:
■

■

XLink – Defines various types of links between resources. These links can model
arbitrary relationships between documents. Those documents can reside inside or
outside the repository.
XInclude – Defines ways to include the content of multiple XML documents or
fragments in a single infoset. This provides for compound documents, which
model inclusion relationships. Compound documents are documents that contain
other documents. More precisely, they are file resources that include documents or
document fragments. The included objects can be file resources in the same
repository or documents or fragments outside the repository.

Each of these standards is very general, and it is not limited to modeling relationships
between XML documents. There is no requirement that the documents linked using
XLink or included in an XML document using XInclude be XML documents.

Using XLink and XInclude with Oracle XML DB 23-1

XLink and XInclude Link Types

Using XLink and XInclude to represent document relationships provides flexibility for
applications, facilitates reuse of component documents, and enables their fine-grained
manipulation (access control, versioning, metadata, and so on). Whereas using XML
data structure (an ancestor–descendents hierarchy) to model relationships requires
those relationships to be relatively fixed, using XLink and XInclude to model
relationships can easily allow for change in those relationships.
For XML schema-based documents to be able to use XLink and
XInclude attributes, the XML schema must either explicitly declare
those attributes or allow any attributes.

Note:

See Also:
■

■

http://www.w3.org/TR/xlink for information about the
XLink standard
http://www.w3.org/TR/xinclude for information about the
XInclude standard

XLink and XInclude Link Types
This section describes XLink and XInclude link types and the relation between these
and Oracle XML DB Repository links. XLink links are more general than repository
links. XLink links can be simple or extended. Oracle XML DB supports only simple
XLink links, not extended links.

XLink and XInclude Links Model Document Relationships
XLink and XInclude links model arbitrary relationships among documents. The
meaning and behavior of a relationship are determined by the applications that use the
link. They are not inherent in the link itself. XLink and XInclude links can be mapped
to Oracle XML DB document links. When document links target Oracle XML DB
Repository resources, they can (according to a configuration option) be hard or weak
links. In this, they are similar to repository links in that context. Repository links can
be navigated using file system-related protocols such as FTP and HTTP. Document
links cannot, but they can be navigated using the XPath 2.0 function fn:doc.
See Also:

"Hard Links and Weak Links" on page 21-7

XLink and XInclude Link Types
XLink and XInclude can provide links to other documents. In the case of XInclude,
attributes href and xpointer are used to specify the target document.
Xlink links can be simple or extended. Simple links are unidirectional, from a source
to a target. Extended links (sometimes called complex) can model relationships
between multiple documents, with different directionalities. Both simple and extended
links can include link metadata. XLink links are represented in XML data using
various attributes of the namespace http://www.w3.org/1999/xlink, which has
the predefined prefix xlink. Simple links are represented in XML data using attribute
type with value simple, that is, xlink:type = "simple". Extended Xlink links
are represented using xlink:type = "extended".
Third-party extended Xlink links are not contained in any of the documents whose
relationships they model. Third-party links can thus be used to relate documents, such
as binary files, that, themselves, have no way of representing a link.

23-2 Oracle XML DB Developer's Guide

XInclude: Compound Documents

The source end of a simple Xlink link (that is, the document containing the link) must
be an XML document. The target end of a simple link can be any document. There are
no such restrictions for extended links. Example 23–3 shows examples of simple links.
The link targets are represented using attribute xlink:href.

XInclude: Compound Documents
XInclude is the W3C recommendation for the syntax and processing model for
merging the infosets of multiple XML documents into a single infoset. Element
xi:include is used to include another document, specifying its URI as the value of
an href attribute. Element xi:include can be nested, so that an included document
can itself include other documents.
(However, an inclusion cycle raises an error in Oracle XML DB. The resources are
created, but an error is raised when the inclusions are expanded.)
XInclude thus provides for compound documents: repository file resources that include
other XML documents or fragments. The included objects can be file resources in the
same repository or documents or fragments outside the repository.
A book might be an example of a typical compound document, as managed by a
content-management system. Each book includes chapter documents, which can each
be managed as separate objects, with their own URLs. A chapter document can have
its own metadata and access control, and it can be versioned. A book can include
(reference) a specific version of a chapter document. The same chapter document can
be included in multiple book documents, for reuse. Because inclusion is modeled
using XInclude, content management is simplified. It is easy, for example, to replace
one chapter in a book by another.
Example 23–1 illustrates an XML Book element that includes four documents. One of
those documents, part1.xml, is also shown. Document part1.xml includes other
documents, representing chapters.
Example 23–1

XInclude Used in a Book Document to Include Parts and Chapters

The top-level document representing a book contains element Book.







A major book part, file (resource) part2.xml, contains a Part element, which
includes multiple chapter documents.








These are some additional features of XInclude:
■

Inclusion of plain text – You can include unparsed, non-XML text using attribute
parse with a value of text: parse = "text".

Using XLink and XInclude with Oracle XML DB 23-3

Using XLink with Oracle XML DB

■

■

Inclusion of XML fragments – You can use an xpointer attribute in an
xi:include element to specify an XML fragment to include, instead of an entire
document.
Fallback processing – In case of error, such as inability to access the URI of an
included document, an xi:include syntax error, or an xpointer reference that
returns null, XInclude performs the treatment specified by element xi:fallback.
This generally specifies an alternative element to be included. The alternative
element can itself use xi:include to include other documents.

Using XLink with Oracle XML DB
Oracle XML DB supports only simple XLink links, not extended XLink links.
When an XML document containing XLink attributes is added to Oracle XML DB
Repository, either as resource content or as user-defined resource metadata, special
processing can occur, depending on how the repository or individual repository
resources are configured. Element XLinkConfig of the resource configuration
document, XDBResConfig.xsd, determines this behavior. In particular, you can
configure resources so that XLink links are ignored, or so that they are mapped to
Oracle XML DB document links. In the latter case, configuration can specify that the
document links are to be hard or weak. Hard and weak document links have the same
properties as hard and weak repository links.
The privileges needed to create or update document links are the same as those
needed to create or update repository links. Even partially updating a document
requires the same privileges needed to delete the entire document and reinsert it. In
particular, even if you update just one document link you must have delete and insert
privileges for each of the documents linked by the document containing the link.
If configuration maps XLink links to document links, then, whenever a document
containing XLink links is added to the repository, the XLink information is extracted
and stored in a system link table. Link target (destination) locations are replaced by
direct paths that are based on the resource OIDs. Configuration can also specify
whether OID paths are to be replaced by named paths (URLs) upon document
retrieval. Using OID paths instead of named paths generally offers a performance
advantage when links are processed, including when resource contents are retrieved.
You can use XLink within resource content, but not within resource metadata.
See Also:
■

"Examining XLink and XInclude Links using DOCUMENT_
LINKS View" on page 23-7

■

Chapter 29, "User-Defined Repository Metadata"

■

"Hard Links and Weak Links" on page 21-7

■

"Configuring Resources for XLink and XInclude" on page 23-9

■

"XDBResConfig.xsd: XML Schema for Resource Configuration" on
page A-9

Using XInclude with Oracle XML DB
Oracle XML DB supports XInclude 1.0 as the standard mechanism for managing
compound documents. It does not support attribute xpointer and the inclusion of
document fragments, however. Only complete documents can be included (using
attribute href).
23-4 Oracle XML DB Developer's Guide

Using XInclude with Oracle XML DB

You can use XInclude to create XML documents that include existing content. You can
also configure the implicit decomposition of non-schema-based XML documents,
creating a set of repository resources that contain XInclude inclusion references.
The content of included documents must be XML data or plain text (with attribute
parse = "text"). You cannot include binary content directly using XInclude, but
you can use XLink to link to binary content.
You can use XInclude within resource content, but not within resource metadata.
See Also: "Examining XLink and XInclude Links using
DOCUMENT_LINKS View" on page 23-7

Expanding Compound-Document Inclusions
When you retrieve a compound document from Oracle XML DB Repository, you have
a choice:
■

■

Retrieve it as is, with the xi:include elements remaining as such. This is the
default behavior.
Retrieve it after replacing the xi:include elements with their targets,
recursively, that is, after expansion of all inclusions. An error is raised if any
xi:include element cannot be resolved.

To retrieve the document in expanded form, use PL/SQL constructor XDBURIType,
passing a value of '1' or '3' as the second argument (flags). Example 23–2 illustrates
this. These are the possible values for the XDBURIType constructor second argument:
■

■

■

1 – Expand all XInclude inclusions before returning the result. If any such
inclusion cannot be resolved according to the XInclude standard fallback
semantics, then raise an error.
2 – Suppress all errors that might occur during document retrieval. This includes
dangling href pointers.
3 – Same as 1 and 2 together.

Example 23–2 retrieves all documents that are under repository folder
public/bookdir, expanding each inclusion:
Example 23–2

Expanding Document Inclusions using XDBURIType

SELECT XDBURIType(ANY_PATH, '1').getXML() FROM RESOURCE_VIEW
WHERE under_path(RES, '/public/bookdir') = 1;
XDBURITYPE(ANY_PATH,'1').GETXML()
--------------------------------




blah blah
foo bar





xyz xyz
abc abc

Using XLink and XInclude with Oracle XML DB 23-5

Using XInclude with Oracle XML DB







blah blah
foo bar





xyz xyz
abc abc


3 rows selected.

(The result shown here corresponds to the resource bookfile.xml shown in
Example 23–8, together with its included resources, chap1.xml and chap2.xml.)
See Also:
■

■

"Versioning, Locking, and Controlling Access to Compound
Documents" on page 23-6 for information about access control
during expansion
Oracle Database PL/SQL Packages and Types Reference for more
information about XDBURIType

Validating Compound Documents
You validate a compound document the way you would any XML document.
However, you can choose to validate it in either form: with xi:include elements as
is or after replacing them with their targets.
You can also choose to use one XML schema to validate the unexpanded form, and
another to validate the expanded form. For example, you might use one XML schema
to validate without first expanding, in order to set up storage structures, and then use
another XML schema to validate the expanded document after it is stored.

Updating Compound Documents
You can update a compound document just as you would update any resource. This
replaces the resource with a new value. It thus corresponds to a resource deletion
followed by a resource insertion. This means, in particular, that any xi:include
elements in the original resource are deleted. Any xi:include elements in the
replacement (inserted) document are processed as usual, according to the
configuration defined at the time of insertion.

Versioning, Locking, and Controlling Access to Compound Documents
The components of a compound document are separate resources. They are versioned
and locked independently, and their access is controlled independently.

23-6 Oracle XML DB Developer's Guide

Examining XLink and XInclude Links using DOCUMENT_LINKS View

■

■

■

Document links to version-controlled resources (VCRs) always resolve to the latest
version of the target resource, or the selected version within the current
workspace. You can, however, explicitly refer to any specific version, by
identifying the target resource by its OID-based path.
Locking a document that contains xi:include elements does not also lock the
included documents. Locking an included document does not also lock
documents that include it.
The access control list (ACL) on each referenced document is checked whenever
you retrieve a compound document with expansion. This is done using the
privileges of the current user (invoker's rights). If privileges are insufficient for any
of the included documents, the expansion is canceled and an error is raised.
See Also:
■
■

■

"Expanding Compound-Document Inclusions" on page 23-5
Chapter 24, "Managing Resource Versions" for information about
VCRs
Chapter 27, "Repository Access Control" for information about
resource ACLs

Examining XLink and XInclude Links using DOCUMENT_LINKS View
You can query the read-only public view DOCUMENT_LINKS to obtain system
information about document links derived from both XLink and XInclude links. The
information in this view includes the following columns, for each link:
■

SOURCE_ID – The source resource OID. RAW(16).

■

TARGET_ID – The target resource OID. RAW(16).

■

TARGET_PATH – Always NULL. Reserved for future use. VARCHAR2(4000).

■

LINK_TYPE – The document link type: Hard or Weak. VARCHAR2(8).

■

■

LINK_FORM – Whether the original link was of form XLink or XInclude.
VARCHAR2(8).
SOURCE_TYPE – Always Resource Content. VARCHAR2(17).

You can obtain information about a resource from this view only if one of the
following conditions holds:
■

■

The resource is a link source, and you have the privilege read-contents or
read-properties on it.
The resource is a link target, and you have the privilege read-properties on it.
Oracle Database Reference for more information on public
view DOCUMENT_LINKS

See Also:

Querying DOCUMENT_LINKS for XLink Information
Example 23–3 shows how XLink links are treated when resources are created, and how
to obtain system information about document links from view DOCUMENT_LINKS. It
assumes that the folder containing the resource has been configured to map XLink
links to document hard links.

Using XLink and XInclude with Oracle XML DB 23-7

Examining XLink and XInclude Links using DOCUMENT_LINKS View

Example 23–3

Querying Document Links Mapped From XLink Links

DECLARE
b BOOLEAN;
BEGIN
b := DBMS_XDB.createResource(
'/public/hardlinkdir/po101.xml',
'
Oracle Corporation
Willard Quine
');
b := DBMS_XDB.createResource(
'/public/hardlinkdir/po102.xml',
'
Oracle Corporation
Haskell Curry

');
END;
/

SELECT r1.ANY_PATH source, r2.ANY_PATH target, dl.LINK_TYPE, dl.LINK_FORM
FROM DOCUMENT_LINKS dl, RESOURCE_VIEW r1, RESOURCE_VIEW r2
WHERE dl.SOURCE_ID = r1.RESID and dl.TARGET_ID = r2.RESID;
SOURCE
----------------------------/public/hardlinkdir/po101.xml
/public/hardlinkdir/po101.xml
/public/hardlinkdir/po102.xml
/public/hardlinkdir/po102.xml
/public/hardlinkdir/po102.xml

TARGET
-----------------------------/public/hardlinkdir/oracle.xml
/public/hardlinkdir/quine.xml
/public/hardlinkdir/oracle.xml
/public/hardlinkdir/curry.xml
/public/hardlinkdir/po101.xml

LINK_TYPE
--------Hard
Hard
Hard
Hard
Hard

LINK_FORM
--------XLink
XLink
XLink
XLink
XLink

See Also: "Mapping XInclude Links to Hard Document Links, with
OID Retrieval" on page 23-12 for an example of configuring a folder to
map XLink links to hard links

Querying DOCUMENT_LINKS for XInclude Information
Example 23–4 queries view DOCUMENT_LINKS to show all document links.
Example 23–4

Querying Document Links Mapped From XInclude Links

DECLARE
ret BOOLEAN;
BEGIN
ret := DBMS_XDB.createResource(
'/public/hardlinkdir/book.xml',
'




');
END;
SELECT r1.ANY_PATH source, r2.ANY_PATH target, dl.LINK_TYPE, dl.LINK_FORM

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Configuring Resources for XLink and XInclude

FROM DOCUMENT_LINKS dl, RESOURCE_VIEW r1, RESOURCE_VIEW r2
WHERE dl.SOURCE_ID = r1.RESID and dl.TARGET_ID = r2.RESID;
SOURCE
-----/public/hardlinkdir/book.xml
/public/hardlinkdir/book.xml
/public/hardlinkdir/book.xml
/public/hardlinkdir/book.xml

TARGET
-----/public/hardlinkdir/toc.xml
/public/hardlinkdir/part1.xml
/public/hardlinkdir/part2.xml
/public/hardlinkdir/index.xml

LINK_TYPE
--------Hard
Hard
Hard
Hard

LINK_FORM
--------XInclude
XInclude
XInclude
XInclude

Configuring Resources for XLink and XInclude
You configure XLink and XInclude treatment for Oracle XML DB Repository resources
as you would configure any other treatment of repository resources—see "Configuring
a Resource" on page 22-2. The rest of this section describes the resource configuration
file that you use as a resource to configure XLink and XInclude processing for other
resources.
A resource configuration file is an XML file that conforms to the XML schema
XDBResConfig.xsd, which is accessible in Oracle XML DB Repository at path
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/XDBResConfig.xsd. You use
elements XLinkConfig and XIncludeConfig, children of element ResConfig, to
configure XLink and XInclude treatment, respectively. If one of these elements is
absent, then there is no treatment of the corresponding type of links.
Both XLinkConfig and XIncludeConfig can have attribute UnresolvedLink and
child elements LinkType and PathFormat. Element XIncludeConfig can also
have child element ConflictRule. If the LinkType element content is None,
however, then there must be no PathFormat or ConflictRule element.
You cannot define any preconditions for XLinkConfig or XIncludeConfig. During
repository resource creation, the ResConfig element of the parent folder determines
the treatment of XLink and XInclude links for the new resource. If the parent folder
has no ResConfig element, then the repository-wide configuration applies.
Any change to the resource configuration file applies only to documents that are
created or updated after the configuration-file change. To process links in existing
documents, use PL/SQL procedure DBMS_XDB.processLinks, after specifying the
appropriate resource configuration parameters.
See Also:
■

■

"Managing XLink and XInclude Links using DBMS_
XDB.processLinks" on page 23-13
Chapter 22, "Configuring Oracle XML DB Repository"

Configuring Treatment of Unresolved Links: UnresolvedLink Attribute
A LinkConfig element can have an UnresolvedLink attribute with a value of
Error (default value) or Skip. This determines what happens if an XLink or XInclude
link cannot be resolved at the time of document insertion into the repository (resource
creation). Error means raise an error and roll back the current operation. Skip means
skip any treatment of the XLink or XInclude link. Skipping treatment creates the
resource with no corresponding document links, and sets the resource's
HasUnresolvedLinks attribute to true, to indicate that the resource has unresolved
links.

Using XLink and XInclude with Oracle XML DB 23-9

Configuring Resources for XLink and XInclude

Using Skip as the value of attribute UnresolvedLink can be especially useful when
you create a resource that contains a cycle of weak links, which would otherwise lead
to unresolved-link errors during resource creation. After the resource and all of its
linked resources have been created, you can use PL/SQL procedure DBMS_
XDB.processLinks to process the skipped links. If all XLink and XInclude links
have been resolved by this procedure, then attribute HasUnresolvedLinks is set to
false.
Resource attribute HasUnresolvedLinks is also set to true for a resource that has a
weak link to a resource that has been deleted. Deleting a resource thus effectively also
deletes any weak links pointing to that resource. In particular, whenever the last hard
link to a resource is deleted, the resource is itself deleted, and all resources that point
to the deleted resource with a weak link have attribute HasUnresolvedLinks set to
true.
See Also:
■
■

"Hard Links and Weak Links" on page 21-7
"Managing XLink and XInclude Links using DBMS_
XDB.processLinks" on page 23-13

Configuring the Document Links to Create: LinkType Element
You use the LinkType element of a resource configuration file to specify the type of
document link to be created whenever an XLink or XInclude link is encountered when
a document is stored in Oracle XML DB Repository. The LinkType element has these
possible values (element content):
■

■

■

None (default) – Ignore XLink or XInclude links: create no corresponding
document links.
Hard – Map XLink or XInclude links to hard document links in repository
documents.
Weak – Map XLink or XInclude links to weak document links in repository
documents.
See Also:
■

Example 23–5

■

Example 23–6

Configuring the Path Format for Retrieval: PathFormat Element
You use the PathFormat element of a resource configuration file to specify the path
format to be used when retrieving documents with xlink:href or
xi:include:href attributes. The PathFormat element has these possible values
(element content) for hard and weak document links:
■

■

OID (default) – Map XLink or XInclude href paths to OID-based paths in
repository documents—that is, use OIDs directly.
Named – Map XLink or XInclude href paths to named paths (URLs) in repository
documents. The path is computed from the internal OID when the document is
retrieved, so retrieval can be slower than in the case of using OID paths directly.

23-10 Oracle XML DB Developer's Guide

Configuring Resources for XLink and XInclude

See Also:
■

Example 23–5

■

Example 23–6

Configuring Conflict-Resolution for XInclude: ConflictRule Element
You use the ConflictRule element of a resource configuration file to specify the
conflict-resolution rules to use if the path computed for a component document is
already present in Oracle XML DB Repository. The ConflictRule element has these
possible values (element content):
■
■

■

Error (default) – Raise an error.
Overwrite – Update the document targeted by the existing repository path,
replacing it with the document to be included. If the existing document is a
version-controlled resource, then it must already be checked out, unless it is
autoversioned. Otherwise, an error is raised.
Syspath – Change the path to the included document to a new, system-defined
path.
See Also: Chapter 24, "Managing Resource Versions" for information
about version-controlled resources

Configuring Decomposition of Documents using XInclude: SectionConfig Element
You use the SectionConfig element of a resource configuration file to specify how
non-schema-based XML documents are to be decomposed when added to Oracle
XML DB Repository, to create a set of resources that contain XInclude inclusion
references. You use simple XPath expressions in the resource configuration file to
identify which parts of a document to map to separate resources, and which resources
to map them to.
Element SectionConfig contains one or more Section elements, each of which
contains the following child elements:
■

■

■

sectionPath – Simple XPath 1.0 expression that identifies a section root. This
must use only child and descendant axes, and it must not use wildcards.
documentPath (optional) – Simple XPath 1.0 expression that is evaluated to
identify the resources to be created from decomposing the document according to
sectionPath. The XPath expression must use only child, descendant, and
attribute axes.
namespace (optional) – Namespace in effect for sectionPath and
documentPath.

Element Section also has a type attribute that specifies the type of section to be
created. Value Document means create a document. The default value, None, means
do not create anything. Using None is equivalent to removing the SectionConfig
element. You can thus set the type attribute to None to disable a SectionConfig
element temporarily, without removing it, and then set it back to Document to enable
it again.
If an element in the document being added to the repository matches more than one
sectionPath value, only the first such expression (in document order) is used.
If no documentPath element is present, then the resource created has a
system-defined name, and is put into the folder specified for the original document.

Using XLink and XInclude with Oracle XML DB

23-11

Configuring Resources for XLink and XInclude

See Also:
■

■

Example 23–7, "Configuring XInclude Document Decomposition"
on page 23-12
Example 23–8, "Repository Document, Showing Generated
xi:include Elements" on page 23-13

XLink and XInclude Configuration Examples
Example 23–5 shows a configuration-file section that configures XInclude treatment,
mapping XInclude attributes to Oracle XML DB Repository hard document links.
Repository paths in retrieved resources are configured to be based on resource OIDs.
Example 23–5

Mapping XInclude Links to Hard Document Links, with OID Retrieval


. . .

Hard
OID

. . .


Example 23–6 shows an XLinkConfig section that maps XLink links to weak
document links in the repository. In this case, retrieval of a document uses named
paths (URLs).
Example 23–6

Mapping XLInk Links to Weak Links, with Named-Path Retrieval


. . .

Weak
Named

. . .


Example 23–7 shows a SectionConfig section that specifies that each Chapter
element in an input document is to become a separate repository file, when the input
document is added to Oracle XML DB Repository. The repository path for the resulting
file is specified using configuration element documentPath, and this path is relative
to the location of the resource configuration file of Example 23–6.
Example 23–7

Configuring XInclude Document Decomposition


. . .


//Chapter
concat("chap", @id, ".xml")


. . .


23-12 Oracle XML DB Developer's Guide

Managing XLink and XInclude Links using DBMS_XDB.processLinks

The XPath expression here uses XPath function concat to concatenate the following
strings to produce the resulting repository path to use:
■

chap – (prefix) chap.

■

The value of attribute id of element Chapter in the input document.

■

.xml as a file extension.

For example, a repository path of chap27.xml would result from an input document
with a Chapter element that has an id attribute with value 27:
 ... 

If the configuration document of Example 23–6 and the book document that contains
the XInclude elements are in repository folder /public/bookdir, then the
individual chapter files generated from XInclude decomposition are in files
/public/bookdir/chapN.xml, where the values of N are the values of the id
attributes of Chapter elements.
The book document that is added to the repository is derived from the input book
document. The embedded Chapter elements in the input book document are
replaced by xi:include elements that reference the generated chapter
documents—Example 23–8 illustrates this.
Example 23–8

Repository Document, Showing Generated xi:include Elements

SELECT XDBURIType('/public/bookdir/bookfile.xml').getclob() FROM DUAL;
XDBURITYPE('/PUBLIC/BOOKDIR/BOOKFILE.XML').GETCLOB()
-------------------------------------------------------------------------------





See Also:
■

Chapter 22, "Configuring Oracle XML DB Repository"

■

XDBResConfig.xsd: XML Schema for Resource Configuration

■

"Configuring Decomposition of Documents using XInclude:
SectionConfig Element" on page 23-11

Managing XLink and XInclude Links using DBMS_XDB.processLinks
You can use PL/SQL procedure DBMS_XDB.processLinks to manually process all
XLink and XInclude links in a single document or in all documents of a folder. Pass
RECURSIVE as the mode argument to this procedure, if you want to process all
hard-linked subfolders recursively. All XLink and XInclude links are processed
according to the corresponding configuration parameters. If any of the links within a
resource cannot be resolved, the resource's HasUnresolvedLinks attribute is set to
true, to indicate that the resource has unresolved links. The default value of attribute
HasUnresolvedLinks is false.
See Also: "Configuring Treatment of Unresolved Links:
UnresolvedLink Attribute" on page 23-9

Using XLink and XInclude with Oracle XML DB

23-13

Managing XLink and XInclude Links using DBMS_XDB.processLinks

23-14 Oracle XML DB Developer's Guide

24
Managing Resource Versions
This chapter describes how to create and manage versions of Oracle XML DB
resources.
This chapter contains these topics:
■

Overview of Oracle XML DB Versioning

■

Versioning and Resource IDs

■

Versioning and ACLs

■

Resource Versioning Examples

Overview of Oracle XML DB Versioning
Versioning lets you create and manage different versions of a resource in Oracle
XML DB Repository. A record, or history, is kept of all changes to an Oracle XML DB
resource that is under version control. When you update a version-controlled resource,
Oracle XML DB stores the pre-update contents as a separate resource version – a
snapshot for the historical record.
Versioning features include the following:
■

Version control for a resource.
You can turn version control on or off for an Oracle XML DB Repository resource.

■

Updating a version-controlled resource.
When Oracle XML DB updates a version-controlled resource, it creates a new
version of the resource. This new version is not deleted from the database when
you delete the version-controlled resource.

■

Accessing a version-controlled resource.
You can access a version-controlled resource the same way you access any other
resource.

■

Accessing a resource version.
To access a particular version of a resource, you use the resource ID of that version.
The resource ID can be obtained from the resource version history or from the
version-controlled resource itself. See "Versioning and Resource IDs".

Table 24–1 lists some terms used in this chapter.

Managing Resource Versions 24-1

Versioning and Resource IDs

Table 24–1

Oracle XML DB Versioning Terms

Term

Description

Versionable resource

A resource that can be put under version control. All Oracle XML DB resources
except folders and ACLs are versionable.

Version-controlled
resource

A resource that is under version control.

Version resource

A particular version of a version-controlled resource. A version resource is itself a
resource. It is system-generated, and it has no associated path name. It is read-only (it
cannot be updated or deleted).

checkOut, checkIn,
unCheckOut

Operations for managing version-controlled resources. You must use checkOut
before you can modify a version-controlled resource. Use checkIn to make your
changes permanent. Use unCheckOut to cancel your changes. (Use COMMIT after
each of these operations.)

Oracle XML DB supports version control only for Oracle
XML DB resources. It does not support version control for
user-defined tables or data in Oracle Database.

Note:

Oracle does not guarantee preservation of the resource ID of a
version across check-in and check-out. Everything except the
resource ID of the latest version is preserved.
Oracle XML DB supports versioning of XML resources that are not
XML schema-based. It also supports versioning of XML
schema-based resources and resources that contain XML
schema-based metadata, but only if the underlying tables have no
associated triggers or constraints.
If hierarchy is enabled for a table, then the table has a trigger. This
includes tables that are created as part of XML schema registration,
for which the default behavior is to enable hierarchy.
Be aware also that if you query one of the tables underlying a
resource, the query can return data from multiple versions of the
resource. This is because the data for the different resource versions
is stored in the same underlying table, using different rows.

Versioning and Resource IDs
A resource object ID, or resource ID, is a unique, constant, system-generated identifier
for an Oracle XML DB resource. Each resource has a resource ID. This includes version
resources, which are system-generated resources that do not have any path names. A
resource ID is sometimes called a RESID.
You use PL/SQL package DBMS_XDB_VERSION to put a resource under
version-control and manage different versions of it. Some of the DBMS_XDB_VERSION
routines accept the path name of a version-controlled resource as argument and return
the resource ID of the relevant version resource.
For example, you use function DBMS_XDB_VERSION.makeVersioned to put a
resource under version control, that is, to turn it into a version-controlled resource. It
accepts as argument a repository path to the resource.
You need not use the same path name for a given version-controlled resource when
you perform various versioning operations on it, but the path names you use must all
refer to the same resource.
24-2 Oracle XML DB Developer's Guide

Versioning and Resource IDs

Whenever a path name is passed as an argument representing a version-controlled
resource, it is the latest (that is, the current) version of the resource that is used. A path
name always stands for the latest version. The only way you can refer to a version other
than the current version is to use its resource ID.
The resource ID of a given version is constant. Remember that a version is itself a
resource, and the resource ID of a resource never changes.
Each time you check in a version-controlled resource, Oracle XML DB creates a new
version resource. A version resource is a snapshot of a resource (its content and
metadata) together with a resource ID. The collection of version resources for a given
version-controlled resource constitutes a historical sequence of previous versions, the
version series or history of the resource.
When you check in a version-controlled resource that has resource ID R, Oracle
XML DB creates a new resource ID, P, which refers to a snapshot of the resource (both
content and metadata), as it was before it was last checked out. The snapshot was
made before check-out, but the associated version resource (and its resource ID P) are
created at check-in time. Together, the new resource ID P and the snapshot it refers to
thus represent the previous, not the current, version of the resource. Resource ID R
continues to refer to the current version.
Put another way, when you check in a version-controlled resource, a version resource
is created that represents the previous state of the version-controlled resource. Like
any new resource, this new version resource is allocated a new resource ID (P).
You can think about making a version resource (check-in) the way you think about
making a backup copy of a file: Just as you give a new name to the backup file, so the
previous-version snapshot of a resource is given a new resource ID. The current
resource retains the original resource ID, just as your working file keeps its original
name.
What this means is that when you check in a resource, in order to "create a new
version", what's really new is the version resource (resource ID P and the snapshot it
references) that represents the old (previous) version. The newest, or latest, version of
the resource (R) is really just the current version. Remember: new version resource =
old (previous) version of the resource content and metadata.
Resource ID R refers to the current version of the version-controlled resource
throughout its lifetime, from the moment it was put under version control until it is
deleted. You can always access the latest version of a resource using its original
resource ID.
When you need to refer to a previous version of a resource, you must use its resource
ID to reference it. You cannot use a path name. You can use function DBMS_XDB_
VERSION.getPredsByRESID to obtain the resource ID of the previous version of a
given resource.
If you delete a resource, then any subsequent reference to it,
whether by resource ID or path name, raises an error (typically
ORA-31001: Invalid resource handle or path name). You
cannot access any version of a version-controlled resource that has
been deleted.

Note:

Managing Resource Versions 24-3

Versioning and ACLs

Versioning and ACLs
A version resource is immutable. It is a snapshot of resource content and metadata,
plus a resource ID, and both snapshot and ID are static. Likewise, the ACL of a version
resource cannot be changed.
You can modify the ACL of a version-controlled resource that you have checked out.
When you check it in, the modified ACL continues to be associated with the current
(latest) version of the resource, and the previous version, that is, the newly created
version resource, is associated with the ACL before it was modified. That is, the
previous version is associated with the previous ACL, and the current version is
associated with the updated ACL.
What is important to keep in mind is this:
■
■

■

■

Different versions of a resource can have different ACLs associated with them.
You can modify the ACL associated with the current version after you check out
the resource.
Check-in associates the ACL as it was before check-out with the newly created
version resource, that is, with the previous version of the resource.
The ACL associated with a given version remains the same.

Resource Versioning Examples
This section presents examples that do the following:
■

Put a resource under version control, that is, create a version-controlled resource –
Example 24–2

■

Retrieve the content of the resource by referring to the resource ID – Example 24–3

■

Check out the version-controlled resource (for all users) – Example 24–4

■

Update the resource content – Example 24–5

■

Check in the resource – Example 24–6

■

■

Retrieve the content and metadata of both the new and old versions of the
resource – Example 24–7, Example 24–8, Example 24–9
Cancel a resource check-out – Example 24–10

Example 24–3 creates an Oracle XML DB Repository resource at repository path
/public/t1.txt. The resource has as content the text Mary had a little lamb.
The example uses SQL*Plus command VARIABLE to declare bind variables
targetPath, current_RESID, and previous_RESID, which are used in other
examples in this section.
Example 24–1

Creating a Repository Resource

VARIABLE targetPath
VARIABLE current_RESID
VARIABLE previous_RESID

VARCHAR2(700)
VARCHAR2(32)
VARCHAR2(32)

DECLARE
res BOOLEAN;
BEGIN
:targetPath := '/public/t1.txt';
IF (DBMS_XDB.existsResource(:targetPath))
THEN DBMS_XDB.deleteResource(:targetPath);

24-4 Oracle XML DB Developer's Guide

Resource Versioning Examples

END IF;
res := DBMS_XDB.createResource(:targetPath, 'Mary had a little lamb');
END;
/

The new resource is not version-controlled. Example 24–2 uses PL/SQL function
makeVersioned to put it under version control. This function returns the resource ID
of the first version resource for the version-controlled resource. The function does not
auto-commit. You must explicitly use COMMIT.
Example 24–2

Creating a Version-Controlled Resource

DECLARE
resid DBMS_XDB_VERSION.RESID_TYPE;
BEGIN
resid := DBMS_XDB_VERSION.makeVersioned(:targetPath);
:current_RESID := resid;
COMMIT;
END;
/

Example 24–2 also copies the resource ID of the new version resource to bind variable
current_RESID. Example 24–3 shows how to use type constructor XDBUritype
together with PL/SQL function createOIDPath to retrieve the resource content by
referencing the resource ID.
Example 24–3

Retrieving Resource Content by Referencing the Resource ID

SELECT XDBURIType(DBMS_XDB.createOIDPath(:current_RESID)).getClob() FROM DUAL;
XDBURITYPE(DBMS_XDB.CREATEOIDPATH(:CURRENT_RESID)).GETCLOB()
-----------------------------------------------------------Mary had a little lamb
1 row selected.

Example 24–4 checks out the version-controlled resource (and commits), so that it can
be modified. Note that any user can modify a resource that has been checked out.
Example 24–4

Checking Out a Version-Controlled Resource

BEGIN
DBMS_XDB_VERSION.checkOut(:targetPath);
COMMIT;
END;
/

Example 24–5 updates the content of the checked-out resource. Before the (LOB)
content can be updated, you must lock the resource. The example uses a dummy
update of the resource display name (a scalar attribute) to do this.
Example 24–5

Updating Resource Content

DECLARE
content
newContentBlob
newContentClob
source_offset
target_offset
warning

BLOB;
BLOB;
CLOB;
INTEGER := 1;
INTEGER := 1;
INTEGER;

Managing Resource Versions 24-5

Resource Versioning Examples

lang_context
INTEGER := 0;
BEGIN
-- Lock the resource using a dummy update.
UPDATE RESOURCE_VIEW
SET RES =
updateXML(RES, '/Resource/DisplayName/text()',
XMLCast(XMLQuery(
'declare namespace ns =
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
$r/ns:Resource/ns:DisplayName/text()'
PASSING RES AS "r" RETURNING CONTENT)
AS VARCHAR2(128)))
WHERE equals_path(res, :targetPath) = 1;
-- Get the LOB locator.
SELECT XMLCast(XMLQuery('declare namespace ns =
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
$r/ns:Resource/ns:XMLLob'
PASSING RES AS "r" RETURNING CONTENT)
AS BLOB)
INTO content FROM RESOURCE_VIEW
WHERE equals_path(RES, :targetPath) = 1;
-- Update the LOB.
newContentClob := 'Hickory dickory dock, the mouse ran up the clock';
DBMS_LOB.createTemporary(newContentBlob, false, DBMS_LOB.CALL);
DBMS_LOB.convertToBlob(newContentBlob, newContentClob,
DBMS_LOB.getLength(newContentClob),
source_offset, target_offset,
nls_charset_id('AL32UTF8'), lang_context, warning);
DBMS_LOB.open(content, DBMS_LOB.lob_readwrite);
DBMS_LOB.trim(content, 0);
DBMS_LOB.append(content, newContentBlob);
DBMS_LOB.close(content);
DBMS_LOB.freeTemporary(newContentBlob);
DBMS_LOB.freeTemporary(newContentClob);
COMMIT;
END;
/

Example 24–5 retrieves the LOB content using the LOB locator, which is element
/ns:Resource/ns:XMLLob. It empties the existing content and adds new content
using PL/SQL procedures trim and append in package DBMS_LOB. It commits the
content change.
See Also: Oracle Database SecureFiles and Large Objects Developer's
Guide for information about updating a LOB

At this point, the content has been modified, but this change has not been recorded in
the version series. Example 24–6 checks in the resource and commits the check-in.
Example 24–6

Checking In a Version-Controlled Resource

DECLARE
resid DBMS_XDB_VERSION.RESID_TYPE;
BEGIN
resid := DBMS_XDB_VERSION.checkIn(:targetPath);
:previous_RESID := DBMS_XDB_VERSION.getPredsByRESID(resid)(1);
COMMIT;
END;
/

24-6 Oracle XML DB Developer's Guide

Resource Versioning Examples

PL/SQL function checkIn returns the resource ID of the current version, which is the
same as current_RESID. Example 24–6 passes this value to PL/SQL function
getPredsByRESID. This function returns the list of resource IDs for the (immediate)
predecessors of its argument resource.1 Example 24–6 assigns the first (and only)
element of this list to bind variable previous_RESID.
At this point, the value of current_RESID is the resource ID of the current version,
and the value of previous_RESID is the resource ID of the previous version.
You can retrieve the content or metadata of a resource using any of the following
methods:
■

■

■

XDBURIType together with PL/SQL function DBMS_XDB.createOIDPath –
Retrieve content. See Example 24–3 and Example 24–7.
PL/SQL function DBMS_XDB_VERSION.getContentsCLOBByRESID – Retrieve
content. See Example 24–8.
PL/SQL function DBMS_XDB_VERSION.getResourceByRESID – Retrieve
metadata. See Example 24–9.

You can use XDBURIType with createOIDPath to access resource content using
protocols. For example, you could have Oracle XML DB serve up various versions of a
graphic image file resource for a Web page, setting the HREF for the HTML IMAGE tag
to a value returned by createOIDPath.
Example 24–7 through Example 24–9 use these different methods to retrieve the two
versions of the resource addressed by bind variables current_RESID and
previous_RESID after check-in.
Example 24–7 Retrieving Resource Version Content using XDBURITYPE and
CREATEOIDPATH
SELECT XDBURIType(DBMS_XDB.createOIDPath(:current_RESID)).getClob() FROM DUAL;
XDBURITYPE(DBMS_XDB.CREATEOIDPATH(:CURRENT_RESID)).GETCLOB()
-----------------------------------------------------------Mary had a little lamb
1 row selected.
SELECT XDBURIType(DBMS_XDB.createOIDPath(:previous_RESID)).getClob() FROM DUAL;
XDBURITYPE(DBMS_XDB.CREATEOIDPATH(:PREVIOUS_RESID)).GETCLOB()
------------------------------------------------------------Hickory dickory dock, the mouse ran up the clock
1 row selected.
Example 24–8 Retrieving Resource Version Content using
GETCONTENTSCLOBBYRESID
SELECT DBMS_XDB_VERSION.getContentsCLOBByRESID(:current_RESID) FROM DUAL;
DBMS_XDB_VERSION.GETCONTENTSCLOBBYRESID(:CURRENT_RESID)
------------------------------------------------------Mary had a little lamb

1

In Oracle XML DB, a version resource always has a single predecessor, that is, a single version
that immediately precedes it. The WebDAV standard provides for the possibility of multiple
predecessors.

Managing Resource Versions 24-7

Resource Versioning Examples

1 row selected.
SELECT DBMS_XDB_VERSION.getContentsCLOBByRESID(:previous_RESID) FROM DUAL;
DBMS_XDB_VERSION.GETCONTENTSCLOBBYRESID(:PREVIOUS_RESID)
-------------------------------------------------------Hickory dickory dock, the mouse ran up the clock
1 row selected.
Example 24–9

Retrieving Resource Version Metadata using GETRESOURCEBYRESID

SELECT XMLSerialize(DOCUMENT DBMS_XDB_VERSION.getResourceByRESID(:current_RESID)
AS CLOB INDENT SIZE = 2)
FROM DUAL;

1 row selected.
SELECT XMLSerialize(DOCUMENT DBMS_XDB_VERSION.getResourceByRESID(:previous_RESID)
AS CLOB INDENT SIZE = 2)
FROM DUAL;

1 row selected.

You can cancel a check-out using PL/SQL function DBMS_XDB_
VERSION.unCheckOut. Example 24–10 illustrates this.
Example 24–10

Canceling a Check-Out using UNCHECKOUT

DECLARE
resid DBMS_XDB_VERSION.RESID_TYPE;
BEGIN
resid := DBMS_XDB_VERSION.unCheckOut(:targetPath);
END;
/

Table 24–2 summarizes the subprograms in PL/SQL package DBMS_XDB_VERSION
that are mentioned in this chapter.

Managing Resource Versions 24-9

Resource Versioning Examples

Table 24–2

PL/SQL Functions and Procedures in Package DBMS_XDB_VERSION

Function or Procedure

Description

makeVersioned(pathname Turn a resource with the given path name into a version controlled resource.
VARCHAR2) RETURN DBMS_
If two or more path names refer to the same resource, then the resource is
XDB_VERSION.RESID_
copied, and argument path name is bound with the copy. The new resource is
TYPE;
put under version control. All other path names continue to refer to the original
resource.
The argument is the path name of the resource to be put under version control.
Returns the resource ID of the first version resource of the version-controlled
resource.
This is not an auto-commit SQL operation. An error is raised of you call
makeVersioned for a folder, version resource, or ACL, or if the target resource
does not exist. Note: No error or warning is raised if you call makeVersioned
for a version-controlled resource.
checkOut(pathname
VARCHAR2);

Check out a version-controlled resource. You cannot update or delete a
version-controlled resource until you check it out. Check-out is for all users: any
user can modify a resource that has been checked out.
The argument is the path name of the version-controlled resource to be checked
out. This is not an auto-commit SQL operation. If two users check out the same
version-controlled resource at the same time, then one user must roll back. As a
precaution, commit after checking out and before updating a resource. An error
is raised if the target resource is not under version control, does not exist, or is
already checked out.

checkIn (pathname
Check in a version-controlled resource that has been checked out.
VARCHAR2) RETURN DBMS_
pathname - Path name of the checked-out resource.
XDB_VERSION.RESID_
TYPE;
Returns the resource id of the newly created version.
This is not an auto-commit SQL operation. You need not use the same path
name that was used for check-out. However, the check-in path name and the
check-out path name must reference the same resource, or else results are
unpredictable.
If the resource has been renamed, then the new name must be used when
checking it in. An error is raised if the path name refers to no resource.
Check in a checked-out resource.
unCheckOut(pathname
VARCHAR2) RETURN DBMS_
The argument is the path name of the checked-out resource.
XDB.RESID_TYPE;
Returns the resource id of the version before the resource was checked out. This
is not an auto-commit SQL operation. You need not use the same path name
that was used for check-out. However, the unCheckOut path name and the
check-out path name must reference the same resource, or else results are
unpredictable.
If the resource has been renamed, then the new name must be used for
unCheckOut. An error is raised if the path name refers to no resource.

24-10 Oracle XML DB Developer's Guide

Resource Versioning Examples

Table 24–2 (Cont.) PL/SQL Functions and Procedures in Package DBMS_XDB_VERSION
Function or Procedure

Description

getPredecessors(pathna Given a path name that references a version resource or a version-controlled
resource, return the predecessors of the resource.
me VARCHAR2) RETURN
RESID_LIST_TYPE;
Retrieving predecessors by resource ID, using function getPredsByRESID is
more efficient than by path name, using function getPredecessors.
getPredsByRESID(resid
DBMS_XDB.RESID_TYPE)
RETURN RESID_LIST_
TYPE;

The list of predecessors returned has only one element (the parent): Oracle
XML DB does not support version branching.

getSuccessors(pathname Given a version resource or a version-controlled resource, return the successors
of the resource.
VARCHAR2) RETURN
RESID_LIST_TYPE;
Retrieving successors by resource ID, using function getSuccsByRESID is more
getSuccsByRESID(resid efficient than by path name, using function getSuccessors.
DBMS_XDB.RESID_TYPE)
The list of successors returned has only one element (the parent): Oracle
RETURN RESID_LIST_
XML DB does not support version branching.
TYPE;
getResourceByRESID(res Given a resource ID, return the resource as an XMLType instance.
id DBMS_XDB.RESID_
TYPE) RETURN XMLType;

Managing Resource Versions 24-11

Resource Versioning Examples

24-12 Oracle XML DB Developer's Guide

25
Accessing the Repository using
RESOURCE_VIEW and PATH_VIEW
25

This chapter describes the predefined public views, RESOURCE_VIEW and PATH_
VIEW, that provide access to Oracle XML DB repository data. It discusses Oracle SQL
functions under_path and equals_path that query resources based on their path
names and path and depth that return resource path names and depths, respectively.
This chapter contains these topics:
■

Overview of Oracle XML DB RESOURCE_VIEW and PATH_VIEW

■

RESOURCE_VIEW and PATH_VIEW SQL Functions

■

Using RESOURCE_VIEW and PATH_VIEW SQL Functions

■

Working with Multiple Oracle XML DB Resources

■

Performance Tuning of Oracle XML DB Repository Operations

■

Searching for Resources using Oracle Text
See Also:
■

■

Oracle Database Reference for more information about view PATH_
VIEW
Oracle Database Reference for more information about view
RESOURCE_VIEW

Overview of Oracle XML DB RESOURCE_VIEW and PATH_VIEW
Figure 25–1 shows how Oracle XML DB RESOURCE_VIEW and PATH_VIEW provide a
mechanism for using SQL to access data stored in Oracle XML DB Repository. Data
stored in the repository using protocols such as FTP and WebDAV, or using application
program interfaces (APIs), can be accessed in SQL using RESOURCE_VIEW values and
PATH_VIEW values.
RESOURCE_VIEW consists of a resource, itself an XMLType, that contains the name of
the resource that can be queried, its ACLs, and its properties, static or extensible.
■

■

If the content comprising the resource is XML data stored somewhere in an
XMLType table or view, then the RESOURCE_VIEW points to the XMLType row that
stores the content.
If the content is not XML data, then the RESOURCE_VIEW stores it as a LOB.

Accessing the Repository using RESOURCE_VIEW and PATH_VIEW

25-1

Overview of Oracle XML DB RESOURCE_VIEW and PATH_VIEW

As of Oracle Database Release 11.2.0.1.0, repository content
stored in line as a LOB uses SecureFile LOB storage. Prior to that, it
used BasicFile LOB storage.

Note:

Parent-child relationships between folders (necessary to construct the hierarchy) are
maintained and traversed efficiently using the hierarchical repository index. Text
indexes are available to search the properties of a resource, and internal B-tree indexes
over Names and ACLs speed up access to these attributes of the Resource XMLType.
RESOURCE_VIEW and PATH_VIEW, along with PL/SQL package DBMS_XDB, provide
all query-based access to Oracle XML DB and DML functionality that is available
through the API.
The base table for RESOURCE_VIEW is XDB.XDB$RESOURCE. Access this table only
through RESOURCE_VIEW or the DBMS_XDB API.
See Also:

Chapter 3, "Using Oracle XML DB"

Figure 25–1 Accessing Repository Resources using RESOURCE_VIEW and PATH_VIEW
Query-based
access

RESOURCE_VIEW

PATH_VIEW

SQL
Queries

SQL
Queries

Oracle XML DB
Repository
Oracle XML DB
Resource Table
Content
Properties

Access through:
• WebDav
• FTP
• DBMS_XDB

Path-based
access

Neither RESOURCE_VIEW nor PATH_VIEW contains the root
folder (/) resource. All other repository resources are included.

Note:

RESOURCE_VIEW Definition and Structure
The RESOURCE_VIEW contains one row for each resource in Oracle XML DB
Repository (except for the root folder resource). Table 25–1 describes its structure.

25-2 Oracle XML DB Developer's Guide

Overview of Oracle XML DB RESOURCE_VIEW and PATH_VIEW

Table 25–1

Structure of RESOURCE_VIEW

Column

Data Type Description

RES

XMLType

A resource in the repository (except for the root folder resource)

ANY_PATH VARCHAR2 An (absolute) path to the resource
RESID

Resource OID, which is a unique handle to the resource

RAW

PATH_VIEW Definition and Structure
The PATH_VIEW contains one row for each unique path to access a resource in Oracle
XML DB Repository (except for the root folder resource). Each resource may have
multiple paths, also called links. Table 25–2 describes its structure.
Table 25–2

Structure of PATH_VIEW

Column

Data Type Description

PATH

VARCHAR2 An (absolute) path to repository resource RES

RES

XMLType

The resource referred to by column PATH

LINK

XMLType

Link property

RESID

RAW

Resource OID

Figure 25–2 illustrates the structure of RESOURCE_VIEW and PATH_VIEW.
The path in the RESOURCE_VIEW is an arbitrary one and one of the accessible paths
that can be used to access that resource. Oracle SQL function under_path lets
applications search for resources that are contained (recursively) within a particular
folder, get the resource depth, and so on. Each row in the PATH_VIEW and RESOURCE_
VIEW columns is of XMLType. DML on repository views can be used to insert, rename,
delete, and update resource properties and contents. Programmatic APIs must be used
for some operations, such as creating links to existing resources.
Paths in the ANY_PATH column of the RESOURCE_VIEW and the PATH column in the
PATH_VIEW are absolute paths: they start at the root.
Test resource paths for equality using Oracle SQL function
equals_path: equals_path('/my/path') = 1. Do not test ANY_
PATH for equality against an absolute path: ANY_PATH =
'/my/path'.
Note:

Paths returned by the path function are relative paths under the path name specified
by function under_path. For example, if there are two resources referenced by path
names /a/b/c and /a/d, respectively, then a path expression that retrieves paths
under folder /a returns relative paths b/c and d.
When there are multiple hard links to the same resource, only paths under the path
name specified by function under_path are returned. If /a/b/c, /a/b/d, and /a/e
are all links to the same resource, then a query on PATH_VIEW that retrieves all of the
paths under /a/b returns only /a/b/c and /a/b/d, not /a/e.

Accessing the Repository using RESOURCE_VIEW and PATH_VIEW

25-3

Overview of Oracle XML DB RESOURCE_VIEW and PATH_VIEW

Figure 25–2 RESOURCE_VIEW and PATH_VIEW Structure
RESOURCE_VIEW Columns
Resource as Path
Resource
an XMLType
OID

PATH_VIEW Columns
Path
Resource as Link as
an XMLType XMLType

Resource
OID

Understanding the Difference Between RESOURCE_VIEW and PATH_VIEW
Views RESOURCE_VIEW and PATH_VIEW differ as follows:
■

■

PATH_VIEW displays all the path names to a particular resource. RESOURCE_VIEW
displays one of the possible path names to the resource
PATH_VIEW also displays the properties of the link

Figure 25–3 illustrates this difference between RESOURCE_VIEW and PATH_VIEW.
Because many Internet applications only need one URL to access a resource,
RESOURCE_VIEW is widely applicable.
PATH_VIEW contains the link properties and resource properties, whereas the
RESOURCE_VIEW only contains resource properties.
Whenever possible, use RESOURCE_VIEW, not PATH_VIEW, for better performance.
Because it handles the information for multiple paths, PATH_VIEW access can be
slower. If you use RESOURCE_VIEW, then the database can determine that only one
path is needed, and the index can do less work to determine all the possible paths.
When using the RESOURCE_VIEW, if you specify a path
with functions under_path or equals_path, then they find the
resource regardless of whether or not that path is the arbitrary one
chosen to normally appear with that resource using RESOURCE_
VIEW.

Note:

25-4 Oracle XML DB Developer's Guide

RESOURCE_VIEW and PATH_VIEW SQL Functions

Figure 25–3 RESOURCE_VIEW and PATH_VIEW Explained
In a typical tree the
RESOURCE_VIEW has only
one path

/home

R1
R2
/corp

/role

po_westcoast

po_eastcoast

Target Resource
With PATH_VIEW, to access the target
resource node;You can create a link.
This provides two access paths R1 or R2
to the target node, for faster access.

RESOURCE_VIEW Example:
select path(1) from RESOURCE_VIEW where under_path(res, '/sys',1);
displays one path to the resource:
/home/corp/po_westcoast
PATH_VIEW Example:
select path from PATH_VIEW;
displays all pathnames to the resource:
/home/corp/po_westcoast
/home/role/po_eastcoast

Operations You Can Perform using UNDER_PATH and EQUALS_PATH
You can perform the following operations using Oracle SQL functions under_path
and equals_path:
■

■

Given a path name:
–

Get a resource or its OID

–

List the directory given by the path name

–

Create a resource

–

Delete a resource

–

Update a resource

Given a condition that uses under_path or other SQL functions:
–

Update resources

–

Delete resources

–

Get resources or their OID

See the "Using RESOURCE_VIEW and PATH_VIEW SQL Functions" and equals_
path.

RESOURCE_VIEW and PATH_VIEW SQL Functions
This section describes Oracle SQL functions that are applicable to RESOURCE_VIEW
and PATH_VIEW.

UNDER_PATH SQL Function
Oracle SQL function under_path uses the hierarchical index of Oracle XML DB
Repository to return the paths to all hard links under a particular path. This index is
designed to speed access when traversing a path (the most common usage).

Accessing the Repository using RESOURCE_VIEW and PATH_VIEW

25-5

RESOURCE_VIEW and PATH_VIEW SQL Functions

If the other parts of the query predicate are very selective, however, then a functional
implementation of under_path can be chosen that walks back up the repository. This
can be more efficient, because fewer links must be traversed. Figure 25–4 shows the
under_path syntax.
Figure 25–4 UNDER_PATH Syntax
,
UNDER_PATH

(

levels

column

,
,

correlation_integer

path_string

)

Table 25–3 details the signature of Oracle SQL function under_path.
Table 25–3

UNDER_PATH SQL Function Signature

Syntax

Description

under_path(resource_column,
pathname);

Determines whether a resource is under a specified path.
Parameters:
■

■

under_path(resource_column,
depth, pathname);

resource_column –The column name or column alias of the
RESOURCE column in the PATH_VIEW or RESOURCE_VIEW.
pathname – The path name to resolve.

Determines whether a resource is under a specified path, with a depth
argument to restrict the number of levels to search.
Parameters:
■

under_path(resource_column,
pathname, correlation);

resource_column – The column name or column alias of the
RESOURCE column in the PATH_VIEW or RESOURCE_VIEW.

■

depth – The maximum depth to search. A nonnegative integer.

■

pathname – The path name to resolve.

Determines if a resource is under a specified path, with a correlation
argument for related SQL functions.
Parameters:
■

■
■

under_path(resource_column,
depth, pathname, correlation);

resource_column – The column name or column alias of the
RESOURCE column in the PATH_VIEW or RESOURCE_VIEW.
pathname – The path name to resolve.
correlation – An integer that can be used to correlate under_
path with related SQL functions (path and depth).

Determines if a resource is under a specified path with a depth
argument to restrict the number of levels to search, and with a
correlation argument for related SQL functions.
Parameters:
■

resource_column – The column name or column alias of the
RESOURCE column in the PATH_VIEW or RESOURCE_VIEW.

■

depth – The maximum depth to search. A nonnegative integer.

■

pathname – The path name to resolve.

■

correlation – An integer that can be used to correlate under_
path with related SQL functions (path and depth).

Note that only one of the accessible paths to the resource must be under
the path argument for a resource to be returned.

25-6 Oracle XML DB Developer's Guide

RESOURCE_VIEW and PATH_VIEW SQL Functions

Function under_path does not follow weak links, because
such traversal could lead to cycles. A weak-link argument to under_
path is resolved correctly, but weak links are not followed when
traversing resources under that path.

Note:

EQUALS_PATH SQL Function
Oracle SQL function equals_path is used to find the resource with the specified path
name. It is functionally equivalent to under_path with a depth restriction of zero.
equals_path(resource_column, pathname);

where:
■

■

resource_column is the column name or column alias of the RESOURCE column
in PATH_VIEW or RESOURCE_VIEW.
pathname is the (absolute) path name to resolve. This can contain components
that are hard or weak resource links.

Figure 25–5 illustrates the complete equals_path syntax.
Figure 25–5 EQUALS_PATH Syntax
,
EQUALS_PATH

(

column

,

path_string

correlation_integer
)

Note:
■

■

Test resource paths for equality using Oracle SQL function
equals_path: equals_path('/my/path') = 1. Do not test
ANY_PATH for equality against an absolute path: ANY_PATH =
'/my/path'.
Use bind variables, instead of hard-coded strings, with equals_
path.

PATH SQL Function
Oracle SQL function path returns the relative path name of the resource under the
specified pathname argument. Note that the path column in the RESOURCE_VIEW
always contains the absolute path of the resource. The path syntax is:
path(correlation);

where:
■

correlation is an integer that can be used to correlate under_path with
related SQL functions (path and depth).
If a path is not under the specified pathname argument, a
NULL value is returned as the output of the current path.

Note:

Figure 25–6 illustrates the path syntax.

Accessing the Repository using RESOURCE_VIEW and PATH_VIEW

25-7

Using RESOURCE_VIEW and PATH_VIEW SQL Functions

Figure 25–6 PATH Syntax
PATH

(

correlation_integer

)

DEPTH SQL Function
Oracle SQL function depth returns the folder depth of the resource under the
specified starting path.
depth(correlation);

where:
correlation is an integer that can be used to correlate under_path with related
SQL functions (path and depth).

Using RESOURCE_VIEW and PATH_VIEW SQL Functions
The following RESOURCE_VIEW and PATH_VIEW examples use Oracle SQL functions
under_path, equals_path, path, and depth.

Accessing Repository Data Paths, Resources and Links: Examples
The following examples illustrate how you can access paths, resources, and link
properties in Oracle XML DB Repository. The first few examples use resources
specified by the following paths:
/a/b/c
/a/b/c/d
/a/e/c
/a/e/c/d

Example 25–1 uses Oracle SQL function path to retrieve the relative paths under path
/a/b.
Example 25–1

Determining Paths Under a Path: Relative

SELECT path(1) FROM RESOURCE_VIEW WHERE under_path(RES, '/a/b', 1) = 1;
PATH(1)
------c
c/d
2 rows selected.

Example 25–2 uses ANY_PATH to retrieve the absolute paths under path /a/b.
Example 25–2

Determining Paths Under a Path: Absolute

SELECT ANY_PATH FROM RESOURCE_VIEW WHERE under_path(RES, '/a/b') = 1;
ANY_PATH
-------/a/b/c
/a/b/c/d
2 rows selected.

25-8 Oracle XML DB Developer's Guide

Using RESOURCE_VIEW and PATH_VIEW SQL Functions

Example 25–3 is the same as Example 25–2, except that the test is not-equals (!=)
instead of equals (=). The query in Example 25–3 finds all paths in the repository that are
not under path /a/b.
Example 25–3

Determining Paths Not Under a Path

SELECT ANY_PATH FROM RESOURCE_VIEW WHERE under_path(RES, '/a/b') != 1
ANY_PATH
-------/a
/a/b
/a/e
/a/e/c
/a/e/c/d
/home
/home/OE
/home/OE/PurchaseOrders
/home/OE/PurchaseOrders/2002
/home/OE/PurchaseOrders/2002/Apr
/home/OE/PurchaseOrders/2002/Apr/AMCEWEN-20021009123336171PDT.xml
/home/OE/PurchaseOrders/2002/Apr/AMCEWEN-20021009123336271PDT.xml
/home/OE/PurchaseOrders/2002/Apr/EABEL-20021009123336251PDT.xml
. . .
/public
/sys
/sys/acls
/sys/acls/all_all_acl.xml
/sys/acls/all_owner_acl.xml
/sys/acls/bootstrap_acl.xml
/sys/acls/ro_all_acl.xml
/sys/apps
/sys/apps/plsql
/sys/apps/plsql/xs
/sys/apps/plsql/xs/netaclrc.xml
/sys/apps/plsql/xs/netaclsc.xml
/sys/databaseSummary.xml
/sys/log
/sys/schemas
/sys/schemas/OE
/sys/schemas/OE/localhost:8080
. . .
326 rows selected.
Example 25–4

Determining Paths using Multiple Correlations

SELECT ANY_PATH, path(1), path(2)
FROM RESOURCE_VIEW
WHERE under_path(RES, '/a/b', 1) = 1 OR under_path(RES, '/a/e', 2) = 1;
ANY_PATH
---------/a/b/c
/a/b/c/d
/a/e/c
/a/e/c/d

PATH(1) PATH(2)
-------- -------c
c/d
c
c/d

4 rows selected.

Accessing the Repository using RESOURCE_VIEW and PATH_VIEW

25-9

Using RESOURCE_VIEW and PATH_VIEW SQL Functions

Example 25–5

Relative Path Names for Three Levels of Resources

SELECT path(1) FROM RESOURCE_VIEW WHERE under_path(RES, 3, '/sys', 1) = 1;

This produces a result similar to the following.
PATH(1)
------acls
acls/all_all_acl.xml
acls/all_owner_acl.xml
acls/bootstrap_acl.xml
acls/ro_all_acl.xml
apps
apps/plsql
apps/plsql/xs
databaseSummary.xml
log
schemas
schemas/OE
schemas/OE/localhost:8080
schemas/PUBLIC
schemas/PUBLIC/www.w3.org
schemas/PUBLIC/xmlns.oracle.com
93 rows selected.
Example 25–6

Extracting Resource Metadata using UNDER_PATH
SELECT ANY_PATH,
XMLQuery('declare namespace ns = "http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
$r/ns:Resource' PASSING RES AS "r" RETURNING CONTENT)
FROM RESOURCE_VIEW WHERE under_path(RES, '/sys') = 1;

This produces a result similar to the following:
ANY_PATH
-------XMLQUERY('DECLARENAMESPACENS="HTTP://XMLNS.ORACLE.COM/XDB/XDBRESOURCE.XSD";(::)$
-------------------------------------------------------------------------------/sys/acls

2008-06-25T13:17:45.164662
2008-06-25T13:17:47.865163
acls
en-US
UTF-8
application/octet-stream
1

/sys/acls/all_all_acl.xml

2008-06-25T13:17:47.759806
2008-06-25T13:17:47.759806
all_all_acl.xml
en-US
UTF-8
text/xml
1

. . .

25-10 Oracle XML DB Developer's Guide

Using RESOURCE_VIEW and PATH_VIEW SQL Functions

41 rows selected.
Example 25–7

Using Functions PATH and DEPTH with PATH_VIEW

SELECT path(1) path, depth(1) depth FROM PATH_VIEW
WHERE under_path(RES, 3, '/sys', 1) = 1;

This produces a result similar to the following:
PATH
---acls
acls/all_all_acl.xml
acls/all_owner_acl.xml
acls/bootstrap_acl.xml
acls/ro_all_acl.xml
apps
apps/plsql
apps/plsql/xs
databaseSummary.xml
log
schemas
schemas/OE
schemas/OE/localhost:8080
schemas/PUBLIC
schemas/PUBLIC/www.w3.org
schemas/PUBLIC/xmlns.oracle.com
. . .
Example 25–8

DEPTH
----1
2
2
2
2
1
2
3
1
1
1
2
3
2
3
3

Extracting Link and Resource Information from PATH_VIEW

SELECT PATH,
XMLCast(XMLQuery(
'declare namespace ns =
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
$l/ns:LINK/ns:Name' PASSING LINK AS "l" RETURNING CONTENT)
AS VARCHAR2(256)),
XMLCast(XMLQuery(
'declare namespace ns =
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
$l/ns:LINK/ns:ParentName' PASSING LINK AS "l" RETURNING CONTENT)
AS VARCHAR2(256)),
XMLCast(XMLQuery(
'declare namespace ns =
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
$l/ns:LINK/ns:ChildName' PASSING LINK AS "l" RETURNING CONTENT)
AS VARCHAR2(256)),
XMLCast(XMLQuery(
'declare namespace ns =
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
$r/ns:Resource/ns:DisplayName'
PASSING RES AS "r" RETURNING CONTENT)
AS VARCHAR2(128))
FROM PATH_VIEW WHERE PATH LIKE '/sys%';

This produces a result similar to the following:
/sys/schemas/PUBLIC/www.w3.org/1999/xlink.xsd
xlink.xsd
/sys/schemas/PUBLIC/www.w3.org/1999/xlink

Accessing the Repository using RESOURCE_VIEW and PATH_VIEW

25-11

Using RESOURCE_VIEW and PATH_VIEW SQL Functions

xlink
/sys/schemas/PUBLIC/www.w3.org/1999/csx.xlink.xsd
csx.xlink.xsd
. . .
118 rows selected.
Example 25–9

All Repository Paths to a Certain Depth Under a Path

SELECT path(1) FROM PATH_VIEW WHERE under_path(RES, 3, '/sys', 1) > 0;

This produces a result similar to the following:
PATH(1)
------acls
acls/all_all_acl.xml
acls/all_owner_acl.xml
acls/bootstrap_acl.xml
acls/ro_all_acl.xml
apps
apps/plsql
apps/plsql/xs
databaseSummary.xml
log
principals
principals/groups
principals/users
schemas
schemas/PUBLIC
schemas/PUBLIC/www.opengis.net
schemas/PUBLIC/www.w3.org
schemas/PUBLIC/xmlns.oracle.com
workspaces
. . .
43 rows selected.
Example 25–10 Locating a Repository Path using EQUALS_PATH
SELECT ANY_PATH FROM RESOURCE_VIEW WHERE equals_path(RES, '/sys') > 0;
ANY_PATH
-------/sys
1 row selected.
Example 25–11 Retrieve RESID of a Given Resource
SELECT RESID FROM RESOURCE_VIEW
WHERE XMLCast(XMLQuery(
'declare namespace ns =
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
$r/ns:Resource/ns:DisplayName'
PASSING RES AS "r" RETURNING CONTENT)
AS VARCHAR2(128))
= 'example';

25-12 Oracle XML DB Developer's Guide

Using RESOURCE_VIEW and PATH_VIEW SQL Functions

This produces a result similar to the following:
RESID
-------------------------------F301A10152470252E030578CB00B432B
1 row selected.
Example 25–12 Obtaining the Path Name of a Resource from its RESID
DECLARE
resid_example RAW(16);
path
VARCHAR2(4000);
BEGIN
SELECT RESID INTO resid_example FROM RESOURCE_VIEW
WHERE XMLCast(XMLQuery(
'declare namespace ns =
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
$r/ns:Resource/ns:DisplayName'
PASSING RES AS "r" RETURNING CONTENT)
AS VARCHAR2(128))
= 'example';
SELECT ANY_PATH INTO path FROM RESOURCE_VIEW WHERE RESID = resid_example;
DBMS_OUTPUT.put_line('The path is: ' || path);
END;
/
The path is: /public/example
PL/SQL procedure successfully completed.
Example 25–13 Folders Under a Given Path
SELECT ANY_PATH FROM RESOURCE_VIEW
WHERE under_path(RES, 1, '/sys') = 1
AND XMLExists('declare namespace ns =
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
$r/ns:Resource[@Container = xs:boolean("true")]'
PASSING RES AS "r");

This produces a result like the following:
ANY_PATH
-------/sys/acls
/sys/apps
/sys/log
/sys/schemas
4 rows selected.
Example 25–14 Joining RESOURCE_VIEW with an XMLType Table
SELECT ANY_PATH, XMLQuery('$p/PurchaseOrder/LineItems'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
FROM purchaseorder po, RESOURCE_VIEW rv
WHERE ref(po)
= XMLCast(XMLQuery('declare default element namespace
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
fn:data(/Resource/XMLRef)'
PASSING rv.RES RETURNING CONTENT)
AS REF XMLType)
Accessing the Repository using RESOURCE_VIEW and PATH_VIEW

25-13

Using RESOURCE_VIEW and PATH_VIEW SQL Functions

AND ROWNUM < 2;
ANY_PATH
-------------------------------------------------------------------------------XMLQUERY('$P/PURCHASEORDER/LINEITEMS'PASSINGPO.OBJECT_VALUEAS"P"RETURNINGCONTENT
-------------------------------------------------------------------------------/home/OE/PurchaseOrders/2002/Apr/AMCEWEN-20021009123336171PDT.xml


Salesman



Big Deal on Madonna Street



Hearts and Minds


. . .

Great Expectations



1 row selected.

Deleting Repository Resources: Examples
The examples in this section illustrate how to delete resources and paths.
If you delete only leaf resources, then you can use DELETE FROM RESOURCE_VIEW,
as in Example 25–15.
Example 25–15 Deleting Resources
DELETE FROM RESOURCE_VIEW WHERE equals_path(RES, '/public/myfile') = 1';

For multiple links to the same resource, deleting from RESOURCE_VIEW deletes the
resource together with all of its links. Deleting from PATH_VIEW deletes only the link
with the specified path.
Example 25–16 illustrates this.
Example 25–16 Deleting Links to Resources

Suppose that '/home/myfile1' is a link to '/public/myfile':
CALL DBMS_XDB.link('/public/myfile', '/home', 'myfile1');

The following SQL DML statement deletes everything in Oracle XML DB Repository
that is found at path /home/myfile1 – both the link and the resource:
DELETE FROM RESOURCE_VIEW WHERE equals_path(RES, '/home/myfile1') = 1;

The following DML statement deletes only the link with path /home/file1:
DELETE FROM PATH_VIEW WHERE equals_path(RES, '/home/file1') = 1;
25-14 Oracle XML DB Developer's Guide

Using RESOURCE_VIEW and PATH_VIEW SQL Functions

Deleting Nonempty Folder Resources
The DELETE DML operator is not allowed on a nonempty folder. If you try to delete a
nonempty folder, you must first delete its contents and then delete the resulting empty
folder. This rule must be applied recursively to any folders contained in the target
folder.
However, the order of the paths returned from a WHERE clause is not guaranteed, and
the DELETE operator does not allow an ORDER BY clause in its table-expression
subclause. You cannot do the following:
DELETE FROM (SELECT 1 FROM RESOURCE_VIEW
WHERE under_path(RES, '/public', 1) = 1
ORDER BY depth(1) DESCENDING);

Example 25–17 illustrates how to delete a nonempty folder: folder example is deleted,
along with its subfolder example1.
Example 25–17 Deleting a Nonempty Folder
SELECT PATH FROM PATH_VIEW WHERE under_path(RES, '/home/US1') = 1;
PATH
-------------------------/home/US1/example
/home/US1/example/example1
2 rows selected.
DECLARE
CURSOR c1 IS
SELECT ANY_PATH p FROM RESOURCE_VIEW
WHERE under_path(RES, '/home/US1', 1) = 1
AND XMLExists('declare namespace ns =
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
$r/ns:Resource[ns:Owner="US1"]' PASSING RES AS "r")
ORDER BY depth(1) DESC;
del_stmt VARCHAR2(500) :=
'DELETE FROM RESOURCE_VIEW WHERE equals_path(RES, :1)=1';
BEGIN
FOR r1 IN c1 LOOP
EXECUTE IMMEDIATE del_stmt USING r1.p;
END LOOP;
END;
/
PL/SQL procedure successfully completed.
SELECT PATH FROM PATH_VIEW WHERE under_path(RES, '/home/US1') = 1;
no rows selected

As always, take care to avoid deadlocks with concurrent
transactions when operating on multiple rows.

Note:

Updating Repository Resources: Examples
This section illustrates how to update resources and paths.
Example 25–18 changes the resource at path /test/HR/example/paper.
Accessing the Repository using RESOURCE_VIEW and PATH_VIEW

25-15

Using RESOURCE_VIEW and PATH_VIEW SQL Functions

Example 25–18 Updating a Resource

This is the complete resource before the update operation:
SELECT XMLSerialize(DOCUMENT r.RES AS CLOB)
FROM RESOURCE_VIEW r WHERE equals_path(r.RES, '/test/HR/example/paper') = 1;
XMLSERIALIZE(DOCUMENTR.RESASCLOB)
-------------------------------------------------------------------------------
1 row selected.

All of the XML elements shown here are resource metadata elements, with the
exception of Contents, which contains the resource content.
This UPDATE statement updates (only) the DisplayName metadata element.
UPDATE RESOURCE_VIEW r
SET r.RES = updateXML(r.RES, '/Resource/DisplayName/text()', 'My New Paper')
WHERE equals_path(r.RES, '/test/HR/example/paper') = 1;
1 row updated.
SELECT XMLSerialize(DOCUMENT r.RES AS CLOB)
FROM RESOURCE_VIEW r WHERE equals_path(r.RES, '/test/HR/example/paper') = 1;
XMLSERIALIZE(DOCUMENTR.RESASCLOB)
-------------------------------------------------------------------------------
1 row selected.

See Also: Chapter 29, "User-Defined Repository Metadata" for
additional examples of updating resource metadata

Note that, by default, the DisplayName element content, paper, was the same text as
the last location step of the resource path, /test/HR/example/paper. This is only
the default value, however. The DisplayName is independent of the resource path, so
updating it does not change the path.
Element DisplayName is defined by the WebDAV standard, and it is recognized by
WebDAV applications. Applications, such as an FTP client, that are not WebDAV-based
do not recognize the DisplayName of a resource. An FTP client lists the resource as
paper (using FTP command ls, for example) even after the UPDATE operation.
Example 25–19 changes the path for the resource from /test/HR/example/paper
to /test/myexample. It is analogous to using the UNIX or Linux command mv
/test/HR/example/paper /test/myexample.
Example 25–19 Updating a Path in the PATH_VIEW
SELECT ANY_PATH FROM RESOURCE_VIEW WHERE under_path(RES, '/test') = 1;
ANY_PATH
-------/test/HR
/test/HR/example
/test/HR/example/paper
3 rows selected.
UPDATE PATH_VIEW
SET PATH = '/test/myexample' WHERE PATH = '/test/HR/example/paper';
ANY_PATH
-------/test/HR
/test/HR/example
/test/myexample
3 rows selected.

See Also: Table 21–3, " Accessing Oracle XML DB Repository: API
Options" on page 21-15 for additional examples that use SQL
functions that apply to RESOURCE_VIEW and PATH_VIEW

Accessing the Repository using RESOURCE_VIEW and PATH_VIEW

25-17

Working with Multiple Oracle XML DB Resources

Working with Multiple Oracle XML DB Resources
The repository operations listed in Table 21–3 on page 21-15 typically apply to a single
resource at a time. To perform the same operation on multiple Oracle XML DB
resources, or to find one or more Oracle XML DB resources that meet a certain set of
criteria, use SQL with RESOURCE_VIEW and PATH_VIEW.
For example, you can perform the following operations:
■

Updating based on attributes – see Example 25–20

■

Finding resources inside a folder – see Example 25–21

■

Copying a set of Oracle XML DB resources – see Example 25–22

Example 25–20 Updating Resources Based on Attributes
UPDATE RESOURCE_VIEW
SET RES = updateXML(RES, '/Resource/DisplayName/text()', 'My New Paper')
WHERE XMLCast(XMLQuery(
'declare namespace ns =
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
$r/ns:Resource/ns:DisplayName'
PASSING RES AS "r" RETURNING CONTENT)
AS VARCHAR2(128))
= 'My Paper';
1 row updated.
SELECT ANY_PATH FROM RESOURCE_VIEW
WHERE XMLCast(XMLQuery('declare namespace ns =
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
$r/ns:Resource/ns:DisplayName'
PASSING RES AS "r" RETURNING CONTENT)
AS VARCHAR2(128))
= 'My New Paper';
ANY_PATH
--------------/test/myexample
1 row selected.
Example 25–21 Finding Resources Inside a Folder
SELECT ANY_PATH FROM RESOURCE_VIEW
WHERE under_path(resource, '/sys/schemas/PUBLIC/xmlns.oracle.com/xdb') = 1;
ANY_PATH
-------------------------------------------------------------/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/XDBFolderListing.xsd
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/XDBResource.xsd
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/XDBSchema.xsd
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/XDBStandard.xsd
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/acl.xsd
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/dav.xsd
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/log
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/log/ftplog.xsd
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/log/httplog.xsd
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/log/xdblog.xsd
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/stats.xsd
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/xdbconfig.xsd

25-18 Oracle XML DB Developer's Guide

Performance Tuning of Oracle XML DB Repository Operations

12 rows selected.

The SQL DML statement in Example 25–22 copies all of the resources in folder public
to folder newlocation. It is analogous to the UNIX or Linux command cp
/public/* /newlocation. Target folder newlocation must exist before the copy.
Example 25–22 Copying Resources
SELECT PATH FROM PATH_VIEW WHERE under_path(RES, '/test') = 1;
PATH
----------------/test/HR
/test/HR/example
/test/myexample
3 rows selected.
INSERT INTO PATH_VIEW
SELECT '/newlocation/' || path(1), RES, LINK, NULL FROM PATH_VIEW
WHERE under_path(RES, '/test', 1) = 1
ORDER BY depth(1);
3 rows created.
SELECT PATH FROM PATH_VIEW WHERE under_path(RES, '/newlocation') = 1;
PATH
-----------------------/newlocation/HR
/newlocation/HR/example
/newlocation/myexample
3 rows selected.

Performance Tuning of Oracle XML DB Repository Operations
This section includes some guidelines for improving the performance of repository
operations such as resource creation and querying.
For optimal performance of queries on repository resources, gather statistics for the
optimizer using procedure DBMS_XDB_ADMIN.gatherRepositoryStats after
resource creation. To use gatherRepositoryStats, you need role DBA or role
XDBADMIN with privilege ANALYZE ANY.
Folders that contain a large number of resources can negatively affect concurrency,
particularly when many resources are created or deleted. As a rule of thumb, do not
have folders that contain more than 10,000 resources. This empirical limit is based on
the database block size and the average filename length.
If you create resources in bulk, perform a COMMIT operation at least every 1,000
resources. Performance can be negatively impacted if you commit very often or you
commit less often than every 1,000 resource creations.
When creating a file resource that is an XML Schema-based document for which the
XML schema is known, specify the XML schema URL as a parameter to PL/SQL
function DBMS_XDB.createResource. This saves preparsing the document to
determine the XML schema.

Accessing the Repository using RESOURCE_VIEW and PATH_VIEW

25-19

Searching for Resources using Oracle Text

Oracle XML DB uses configuration file xdbconfig.xml for configuring the system
and protocol environment. This file includes an element parameter,
resource-view-cache-size, that defines the size in dynamic memory of the
RESOURCE_VIEW cache. The default value is 1048576.
The performance of some queries on RESOURCE_VIEW and PATH_VIEW can be
improved by tuning resource-view-cache-size. In general, the bigger the cache
size, the faster the query. The default resource-view-cache-size is appropriate
for most cases, but you may want to enlarge your resource-view-cache-size
element when querying a sizable RESOURCE_VIEW.
The default limits for the following elements are soft limits. The system automatically
adapts when these limits are exceeded.
■

■

xdbcore-loadableunit-size – This element indicates the maximum size to
which a loadable unit (partition) can grow in Kilobytes. When a partition is read
into memory or a partition is built while consuming a new document, the partition
is built until it reaches the maximum size. The default value is 16 KB.
xdbcore-xobmem-bound – This element indicates the maximum memory in
kilobytes that a document is allowed to occupy. The default value is 1024 KB. Once
the document exceeds this number, some loadable units (partitions) are swapped
out.
See Also:
■
■

■

Chapter 34, "Administering Oracle XML DB"
Oracle Database PL/SQL Packages and Types Reference for
information about PL/SQL function DBMS_
XDB.createResource
Oracle Database 2 Day + Security Guide for information about
database schema XDB

Searching for Resources using Oracle Text
Table XDB$RESOURCE in database schema XDB stores the metadata and content of
repository resources. You can search for resources that contain a specific keyword by
using Oracle SQL function contains with RESOURCE_VIEW or PATH_VIEW.
Example 25–23 Find All Resources Containing "Paper"
SELECT PATH FROM PATH_VIEW WHERE contains(RES, 'Paper') > 0;
PATH
----------------------/newlocation/myexample
/test/myexample
2 rows selected.
Example 25–24 Find All Resources Containing "Paper" that are Under a Specified Path
SELECT ANY_PATH FROM RESOURCE_VIEW
WHERE contains(RES, 'Paper') > 0 AND under_path(RES, '/test') > 0;
ANY_PATH
---------------/test/myexample

25-20 Oracle XML DB Developer's Guide

Searching for Resources using Oracle Text

1 row selected.

To evaluate such queries, you must first create a context index on the XDB$RESOURCE
table. Depending on the type of documents stored in Oracle XML DB, choose one of
the following options for creating your context index:
■

If Oracle XML DB contains only XML documents, that is, no binary data, then a
regular Context Index can be created on the XDB$RESOURCE table. This is the case
for Example 25–24.
CREATE INDEX xdb$resource_ctx_i ON XDB.XDB$RESOURCE(OBJECT_VALUE)
INDEXTYPE IS CTXSYS.CONTEXT;

See Also: Chapter 4, "XMLType Operations" and Chapter 12,
"Full-Text Search Over XML Data"
■

If Oracle XML DB contains binary data such as Microsoft Word documents, then a
user filter is required to filter such documents prior to indexing. Use package
DBMS_XDBT (dbmsxdbt.sql) to create and configure the Context Index.
-- Install the package - connected as SYS
@dbmsxdbt
-- Create the preferences
EXEC DBMS_XDBT.createPreferences;
-- Create the index
EXEC DBMS_XDBT.createIndex;

See Also:
■

■

Oracle Database PL/SQL Packages and Types Reference, for
information about installing and using DBMS_XDBT.
"APIs for XML" on page 1-4

Package DBMS_XDBT also includes procedures to synchronize and optimize the index.
You can use procedure configureAutoSync() to automatically sync the index by
using job queues.

Accessing the Repository using RESOURCE_VIEW and PATH_VIEW

25-21

Searching for Resources using Oracle Text

25-22 Oracle XML DB Developer's Guide

26
Accessing the Repository using PL/SQL
This chapter describes the Oracle XML DB resource application program interface
(API) for PL/SQL (PL/SQL package DBMS_XDB). It contains these topics:
■

Overview of PL/SQL Package DBMS_XDB

■

DBMS_XDB: Resource Management

■

DBMS_XDB: ACL-Based Security Management

■

DBMS_XDB: Configuration Management

Overview of PL/SQL Package DBMS_XDB
PL/SQL package DBMS_XDB is the Oracle XML DB resource application program
interface (API) for PL/SQL. It is also known as the PL/SQL foldering API. This API
provides functions and procedures to access and manage Oracle XML DB Repository
resources using PL/SQL. It includes methods for managing resource security and
Oracle XML DB configuration.
Oracle XML DB Repository is modeled on XML, and provides a database file system
for any data. The repository maps path names (or URLs) onto database objects of
XMLType and provides management facilities for these objects.
PL/SQL package DBMS_XDB is an API that you can use to manage all of the following:
■
■

■

Oracle XML DB resources
Oracle XML DB security based on access control lists (ACLs). An ACL is a list of
access control entries (ACEs) that determines which principals (users and roles)
have access to which resources
Oracle XML DB configuration
See Also:
■

Oracle Database PL/SQL Packages and Types Reference

■

"APIs for XML" on page 1-4

DBMS_XDB: Resource Management
Table 26–1 describes DBMS_XDB Oracle XML DB resource management functions and
procedures.

Accessing the Repository using PL/SQL

26-1

DBMS_XDB: Resource Management

Table 26–1

DBMS_XDB Resource Management Functions and Procedures

Function/Procedure

Description

appendResourceMetadata

Add user-defined metadata to a resource.

createFolder

Create a new folder resource.

createOIDPath

Create a virtual path to a resource, based on its object identifier (OID).

createResource

Create a new file resource.

deleteResource

Delete a resource from the repository.

deleteResourceMetadata

Delete specific user-defined metadata from a resource.

existsResource

Indicate whether or not a resource exists, given its absolute path.

getLockToken

Return a resource lock token for the current user, given a path to the resource.

getResOID

Return the object identifier (OID) of a resource, given its absolute path.

getXDB_tablespace

Return the current tablespace of database schema (user account) XDB.

link

Create a link to an existing resource.

lockResource

Obtain a WebDAV-style lock on a resource, given a path to the resource.

purgeResourceMetadata

Delete all user-defined metadata from a resource.

renameResource

Rename a resource.

unlockResource

Unlock a resource, given its lock token and path.

updateResourceMetadata

Modify user-defined resource metadata.

Tip: For optimal performance of queries on repository resources,
gather statistics for the optimizer using procedure DBMS_XDB_
ADMIN.gatherRepositoryStats after resource creation. You need
the XDBADMIN role with privilege ANALYZE ANY or the DBA role to
use gatherRepositoryStats.
See Also:

Oracle Database PL/SQL Packages and Types Reference

The examples in this section illustrate the use of these functions and procedures.
Example 26–1 uses package DBMS_XDB to manage repository resources. It creates the
following:
■

a folder, mydocs, under folder /public

■

two file resources, emp_selby.xml and emp_david.xml

■

two links to the file resources, person_selby.xml and person_david.xml

It then deletes each of the newly created resources and links. The folder contents are
deleted before the folder itself.
Example 26–1

Managing Resources using DBMS_XDB

DECLARE
retb BOOLEAN;
BEGIN
retb := DBMS_XDB.createfolder('/public/mydocs');
retb := DBMS_XDB.createresource('/public/mydocs/emp_selby.xml',
'selby');
retb := DBMS_XDB.createresource('/public/mydocs/emp_david.xml',

26-2 Oracle XML DB Developer's Guide

DBMS_XDB: ACL-Based Security Management

'david');
END;
/
PL/SQL procedure successfully completed.
CALL DBMS_XDB.link('/public/mydocs/emp_selby.xml',
'/public/mydocs',
'person_selby.xml');
Call completed.
CALL DBMS_XDB.link('/public/mydocs/emp_david.xml',
'/public/mydocs',
'person_david.xml');
Call completed.
CALL DBMS_XDB.deleteresource('/public/mydocs/emp_selby.xml');
Call completed.
CALL DBMS_XDB.deleteresource('/public/mydocs/person_selby.xml');
Call completed.
CALL DBMS_XDB.deleteresource('/public/mydocs/emp_david.xml');
Call completed.
CALL DBMS_XDB.deleteresource('/public/mydocs/person_david.xml');
Call completed.
CALL DBMS_XDB.deleteresource('/public/mydocs');
Call completed.

See Also: Chapter 29, "User-Defined Repository Metadata" for
examples using appendResourceMetadata and
deleteResourceMetadata

DBMS_XDB: ACL-Based Security Management
Table 26–2 lists the DBMS_XDB Oracle XML DB ACL- based security management
functions and procedures.
Table 26–2

DBMS_XDB: Security Management Procedures and Functions

Function/Procedure

Description

ACLCheckPrivileges Checks the access privileges granted to the current user by an ACL.
changePrivileges

Adds an ACE to a resource ACL.

checkPrivileges

Checks the access privileges granted to the current user for a
resource.

getACLDocument

Retrieves the ACL document that protects a resource, given the path
name of the resource.

getPrivileges

Returns all privileges granted to the current user for a resource.

setACL

Sets the ACL on a resource.

See Also:
■

Oracle Database PL/SQL Packages and Types Reference

■

Oracle XML Developer's Kit Programmer's Guide

Accessing the Repository using PL/SQL

26-3

DBMS_XDB: ACL-Based Security Management

The examples in this section illustrate the use of these functions and procedures.
In Example 26–2, database user HR creates two resources: a folder, /public/mydocs,
with a file in it, emp_selby.xml. Procedure getACLDocument is called on the file
resource, showing that the  user for the document is PUBLIC.
Example 26–2

Using DBMS_XDB.GETACLDOCUMENT

CONNECT hr
Enter password: password
Connected.
DECLARE
retb BOOLEAN;
BEGIN
retb := DBMS_XDB.createFolder('/public/mydocs');
retb := DBMS_XDB.createResource('/public/mydocs/emp_selby.xml',
'selby');
END;
/
PL/SQL procedure successfully completed.
SELECT XMLSerialize(DOCUMENT
DBMS_XDB.getACLDocument('/public/mydocs/emp_selby.xml')
AS CLOB)
FROM DUAL;
XMLSERIALIZE(DOCUMENTDBMS_XDB.GETACLDOCUMENT('/PUBLIC/MYDOCS/EMP_SELBY.XML')ASCL
-------------------------------------------------------------------------------

true
PUBLIC





1 row selected.

In Example 26–3, the system manager connects and uses procedure setACL to give the
owner (database schema HR) all privileges on the file resource created in
Example 26–2. Procedure getACLDocument then shows that the  user
is dav:owner, the owner (HR).
Example 26–3

Using DBMS_XDB.SETACL

CONNECT SYSTEM
Enter password: password
Connected.
-- Give all privileges to owner, HR.
CALL DBMS_XDB.setACL('/public/mydocs/emp_selby.xml',
'/sys/acls/all_owner_acl.xml');
Call completed.

26-4 Oracle XML DB Developer's Guide

DBMS_XDB: ACL-Based Security Management

COMMIT;
Commit complete.
SELECT XMLSerialize(DOCUMENT
DBMS_XDB.getACLDocument('/public/mydocs/emp_selby.xml')
AS CLOB)
FROM DUAL;
XMLSERIALIZE(DOCUMENTDBMS_XDB.GETACLDOCUMENT('/PUBLIC/MYDOCS/EMP_SELBY.XML')ASCL
-------------------------------------------------------------------------------

true
dav:owner





1 row selected.

In Example 26–4, user HR connects and uses function changePrivileges to add a
new access control entry (ACE) to the ACL, which gives all privileges on resource
emp_selby.xml to user oe. Procedure getACLDocument shows that the new ACE
was added to the ACL.
Example 26–4

Using DBMS_XDB.CHANGEPRIVILEGES

CONNECT hr
Enter password: password
Connected.
SET SERVEROUTPUT ON
-- Add an ACE giving privileges to user OE
DECLARE
r
PLS_INTEGER;
ace
XMLType;
ace_data VARCHAR2(2000);
BEGIN
ace_data := '
OE
true

';
ace := XMLType.createXML(ace_data);
r := DBMS_XDB.changePrivileges('/public/mydocs/emp_selby.xml', ace);
END;
/
PL/SQL procedure successfully completed.

Accessing the Repository using PL/SQL

26-5

DBMS_XDB: ACL-Based Security Management

COMMIT;
SELECT XMLSerialize(DOCUMENT
DBMS_XDB.getACLDocument('/public/mydocs/emp_selby.xml')
AS CLOB)
FROM DUAL;
XMLSERIALIZE(DOCUMENTDBMS_XDB.GETACLDOCUMENT('/PUBLIC/MYDOCS/EMP_SELBY.XML')ASCL
-------------------------------------------------------------------------------

true
dav:owner





true
OE





1 row selected.

In Example 26–5, user oe connects and calls DBMS_XDB.getPrivileges, which
shows all of the privileges granted to user oe on resource emp_selby.xml.
Example 26–5

Using DBMS_XDB.GETPRIVILEGES

CONNECT oe
Enter password: password
Connected.
SELECT XMLSerialize(DOCUMENT
DBMS_XDB.getPrivileges('/public/mydocs/emp_selby.xml')
AS CLOB)
FROM DUAL;
XMLSERIALIZE(DOCUMENTDBMS_XDB.GETPRIVILEGES('/PUBLIC/MYDOCS/EMP_SELBY.XML')ASCLO
-------------------------------------------------------------------------------







26-6 Oracle XML DB Developer's Guide

DBMS_XDB: Configuration Management














1 row selected.

DBMS_XDB: Configuration Management
Table 26–3 lists the DBMS_XDB Oracle XML DB configuration management functions
and procedures.
Table 26–3

DBMS_XDB: Configuration Management Functions and Procedures

Function/Procedure

Description

cfg_get

Returns the configuration information for the current session.

cfg_refresh

Refreshes the session configuration information using the current Oracle XML DB
configuration file, xdbconfig.xml.

cfg_update

Updates the Oracle XML DB configuration information. This writes the
configuration file, xdbconfig.xml.

getFTPPort

Returns the current FTP port number.

getHTTPPort

Returns the current HTTP port number.

setFTPPort

Sets the Oracle XML DB FTP port to the specified port number.

setHTTPPort

Sets the Oracle XML DB HTTP port to the specified port number.

See Also:

Oracle Database PL/SQL Packages and Types Reference

The examples in this section illustrate the use of these functions and procedures.
Example 26–6 uses function cfg_get to retrieve the Oracle XML DB configuration
file, xdbconfig.xml.
Example 26–6

Using DBMS_XDB.CFG_GET

CONNECT SYSTEM
Enter password: password
Connected.
SELECT DBMS_XDB.cfg_get() FROM DUAL;
DBMS_XDB.CFG_GET()
-------------------------------------------------------------------------------

19
32

true
6000
65536
100
false
3600
/sys/log/xdblog.xml
0
1048576


. . .


. . .


0
local_listener
tcp
64
16384
2000000000
6000
XDB HTTP Server
/sys/log/httplog.xml
0
Basic realm="XDB"

. . .


. . .


1024
16
ace-order


1 row selected.

Example 26–7 illustrates the use of procedure cfg_update. The current configuration
is retrieved as an XMLType instance and modified. It is then rewritten using cfg_
update.
Example 26–7

Using DBMS_XDB.CFG_UPDATE

DECLARE
configxml
SYS.XMLType;
configxml2
SYS.XMLType;
BEGIN
-- Get the current configuration
configxml := DBMS_XDB.cfg_get();

26-8 Oracle XML DB Developer's Guide

DBMS_XDB: Configuration Management

-- Modify the configuration
SELECT updateXML(
configxml,
'/xdbconfig/sysconfig/protocolconfig/httpconfig/http-port/text()',
'8000',
'xmlns="http://xmlns.oracle.com/xdb/xdbconfig.xsd"')
INTO configxml2 FROM DUAL;
-- Update the configuration to use the modified version
DBMS_XDB.cfg_update(configxml2);
END;
/
PL/SQL procedure successfully completed.
SELECT DBMS_XDB.cfg_get() FROM DUAL;
DBMS_XDB.CFG_GET()
-------------------------------------------------------------------------------

15
32

true
6000
65536
100
false
3600
/sys/log/xdblog.xml
1048576


. . .


. . .


8000
. . .


1024
16
ace-order

1 row selected.

Accessing the Repository using PL/SQL

26-9

DBMS_XDB: Configuration Management

26-10 Oracle XML DB Developer's Guide

27
Repository Access Control
Oracle Database provides classic database security such as row-level and column-level
secure access by database users. It also provides fine-grained access control for
resources in Oracle XML DB Repository. This chapter describes the latter. It includes
how to create, set, and modify access control lists (ACLs) and how ACL security
interacts with other Oracle Database security mechanisms.
This chapter contains these topics:
■

Access Control Concepts

■

Database Privileges for Repository Operations

■

Privileges

■

ACLs and ACEs

■

Working with Access Control Lists (ACLs)

■

ACL Caching

■

Repository Resources and Database Table Security

■

Integrating Oracle XML DB with LDAP
See Also:
■

■

■

Chapter 28, "Accessing the Repository using Protocols" for
more information about WebDAV
Chapter 34, "Administering Oracle XML DB" for information
about configuring and administering resource security
"APIs for XML" on page 1-4 for information about the PL/SQL
APIs you can use to manage resource security

Access Control Concepts
This section describes several access control terms and concepts. Each of the entities
described here, user, role, principal, privilege, access control list (ACL), and access
control entry (ACE), is implemented declaratively as an XML document or fragment.
Secure authorization requires defining which users, applications, or functions can have
access to which data, to perform which kinds of operations. There are thus three
dimensions: (1) which users can (2) perform which operations (3) on which data. We speak
of (1) principals, (2) privileges, and (3) objects, corresponding to these three
dimensions, respectively. Principals are users or roles.

Repository Access Control 27-1

Access Control Concepts

Principals and privileges (dimensions 1 and 2) are related in a declarative way by
defining access control lists. These are then related to the third dimension, data, in
various ways, either declaratively or procedurally. For example, you can protect an
Oracle XML DB Repository resource or table data by using PL/SQL procedure DBMS_
XDB.setACL to set its controlling ACL.

Principal: A User or Role
In the context of fine-grained database access control, a principal is a user or a role. A
user can be any person or application that accesses information in the database. A role
is composed of users and possibly other roles, but this recursion cannot be circular.
Ultimately, each role, and thus each principal, corresponds to a set of users.
A user is represented for access control purposes by an XML fragment with element
user. A role is represented by a fragment with element role.
Oracle Database supports the following as principals:
■

■

Database users and database roles. A database user is also sometimes referred to
as a database schema or a user account. When a person or application logs onto
the database, it uses a database user (schema) and password. A database role
corresponds to a set of database privileges that can be granted to database users,
applications, or other database roles—see "Database Roles Map Database
Privileges to Users" on page 27-2.
LDAP users and groups of LDAP users. For details on using LDAP principals see
"Integrating Oracle XML DB with LDAP" on page 27-20.

When a term such as "user" or "role" is used here without qualification, it applies to
each type of user or role. When it is important to distinguish the type, the qualifier
"database" or "LDAP" is used.

Database Roles Map Database Privileges to Users
A database role is granted privileges, just as a database user can be granted privileges.
A database role serves as an intermediary for mapping database privileges to database
users (and applications): a role is granted privileges, and the role is then granted to
users (giving them the privileges). The line between a group of users and a group of
privileges that are granted to those users is blurred a bit in the concept of database
role: the role can serve to group the privileges that are mapped to the users and to
group the users to which the privileges are mapped. The mapping is done by defining
the role and granting it to users, and traditional database terminology considers the
role to be the same thing as the set of privileges that are granted to it.
In the context of fine-grained access control, a different mechanism, an access control list
(ACL), is used as the intermediary that maps privileges to users. A role is simply a set
of users. In this context, the act of associating privileges with users and with roles is
not a database grant. It is a declarative ACL entry, together with a run-time evaluation
of ACLs and resolution of ACL conflicts.
Please keep this terminology difference in mind, to avoid confusion. As a means of
mapping privileges to users, a database role combines some of the functionality that in
an access-control context is divided into (1) principals, (2) privileges, and (3) ACLs. In
access control terminology, roles are classified with users as principals. In traditional
database terminology, roles are instead classified as sets of privileges.

Principal DAV::owner
You can use principal DAV::owner in connection with a given Oracle XML DB
Repository resource to refer to the resource owner. The owner of a resource is one of
27-2 Oracle XML DB Developer's Guide

Access Control Concepts

the properties of the resource. You can use principal DAV::owner to facilitate ACL
sharing among principals, because the owner of a resource often has special rights.

Privilege: A Permission
A privilege is a particular right or permission that can be granted or denied to a
principal. A privilege is aggregate or atomic:
■
■

Aggregate privilege – A privilege that includes other privileges.
Atomic privilege – A privilege that does not include other privileges. It cannot be
subdivided.

Aggregate privileges simplify usability when the number of privileges becomes large,
and they promote interoperability between ACL clients. See "Privileges" on page 27-5.
Aggregate privileges retain their identity: they are not decomposed into the
corresponding atomic (leaf) privileges. In WebDAV terms, Oracle Database aggregate
privileges are not abstract. This implies that an aggregate privilege acts as a set of
pointers to its component privileges, rather than a copy of those components. Thus, an
aggregate privilege is always up to date, even if the definition of a component
changes.
The set of privileges granted to a principal controls whether that principal can perform
a given operation on the data that it protects. For example, if the principal (database
user) HR wants to perform the read operation on a given resource, then read
privileges must be granted to principal HR prior to the read operation.

Access Control Entry (ACE)
An access control entry (ACE) is an XML element (ace) that is an entry in an access
control list (ACL). An ACE either grants or denies access to some repository resource
or other database data by a particular principal (user or role). The ACE does not, itself,
specify which data to protect. That is done outside the ACE and the ACL, by
associating the ACL with target data. One way to make that association is by using
PL/SQL procedure DBMS_XDB.setACL.
See "ACL and ACE Evaluation" on page 27-8.
An Oracle XML DB ACE either grants or denies privileges for a principal. An ace
element has the following:
■
■

■

■

■

■

Operation grant: either true (to grant) or false (to deny) access.
Either a valid principal (element principal) or a completed list of principals
(element invert).
Privileges: A set of privileges to be granted or denied for a particular principal
(element privilege).
Principal format (optional): The format of the principal. An LDAP distinguished
name (DN), a short name (database user/role or LDAP nickname), or an LDAP
GUID. The default value is short name. If the principal name matches both a
database user and an LDAP nickname, it is assumed to refer to the LDAP
nickname.
Collection (optional): A BOOLEAN attribute that specifies whether the principal is a
collection of users (LDAP group or database role) or a single user (LDAP or
database user).
Start and end date (optional): Attributes that define the time period over which an
ACE is valid. See "ACE Validity Time Period" on page 27-10.
Repository Access Control 27-3

Database Privileges for Repository Operations

Example 27–1 shows a simple ACE that grants privilege DAV::all to principal
DAV::owner. It thus grants all privileges to the owner of the resource to which its
ACL applies.
Example 27–1

Simple Access Control Entry (ACE) that Grants a Privilege


true
DAV::owner





Access Control List (ACL)
An access control list (ACL) is a list of access control entries (ACEs). By default, order
in the list is relevant (see "ACL and ACE Evaluation" on page 27-8). Example 27–2
shows a simple ACL that contains only the ACE of Example 27–1.
Example 27–2

Simple Access Control List (ACL) that Grants a Privilege



true
dav:owner






Database Privileges for Repository Operations
Table 27–1 shows the database privileges required for some common operations on
resources in Oracle XML DB Repository. In addition to the privileges listed in column
Privileges Required you must have the resolve privilege for the folder containing
the resource and for all of its parent folders, up to the root folder.
Table 27–1

Database Privileges Needed for Operations on Oracle XML DB Resources

Operation

Description

Privileges Required

CREATE

Create a new resource in folder F

update and link on folder F

DELETE

Delete resource R from folder F

update and unlink-from on R, update
and unlink on folder F

UPDATE

Update the contents or properties of
resources R

update on R

27-4 Oracle XML DB Developer's Guide

Privileges

Table 27–1 (Cont.) Database Privileges Needed for Operations on Oracle XML DB Resources
Operation

Description

Privileges Required

GET

An FTP or HTTP(S) retrieval of resource R

read-properties, read-contents on R

SET_ACL

Set the ACL of a resource R

DAV::write-acl on R

LIST

List the resources in folder F

read-properties on folder F,
read-properties on resources in folder F.
Only those resources on which the user has
read-properties privilege are listed.

See Also: "Upgrading an Existing Oracle XML DB Installation" on
page 34-3 for information about treatment of database access
privileges when upgrading

Privileges
This section describes the privileges that are provided with Oracle Database. These
include the standard WebDAV privileges, which use the WebDAV namespace DAV:1,
and Oracle-specific privileges, which use the Oracle XML DB ACL namespace,
http://xmlns.oracle.com/xdb/acl.xsd, which has the predefined prefix xdb.
See Also: RFC 3744: "Web Distributed Authoring and Versioning
(WebDAV) Access Control Protocol", IETF Network Working Group
Request For Comments #3744, May 2004

Atomic Privileges
Table 27–2 lists the atomic privileges.

Table 27–2

Atomic Privileges

Atomic Privilege

Description

Database
Counterpart

DAV::lock

Lock a resource using WebDAV locks.

UPDATE

DAV::read-current-use
r-privilege-set

Access the DAV::current-user-privilege-set property of a
resource.

N/A

DAV::take-ownership

Take ownership of a resource.

N/A

DAV::unlock

Unlock a resource locked using a WebDAV lock.

UPDATE

DAV::write-content

Modify the content of a resource.

UPDATE

DAV::write-properties

Modify the properties of a resource. Lock or unlock a resource.
Modifiable properties include Author, DisplayName, Language,
CharacterSet, ContentType, SBResExtra, Owner, OwnerID,
CreationDate, Modification Date, ACL, ACLOID, Lock, and
Locktoken.

UPDATE

xdb:link

Allow creation of links from a resource.

INSERT

xdb:link-to

Allow creation of links to a resource.

N/A

xdb:read-acl

Read the ACL of a resource.

SELECT

1

Note the colon (:) as part of the namespace name. DAV: is the namespace itself, not a prefix. A
prefix commonly used for namespace DAV: is dav, but this is only conventional. dav is not a
predefined prefix for Oracle XML DB.

Repository Access Control 27-5

ACLs and ACEs

Table 27–2 (Cont.) Atomic Privileges
Atomic Privilege

Description

Database
Counterpart

xdb:read-contents

Read the contents of a resource.

SELECT

xdb:read-properties

Read the properties of a resource.

SELECT

xdb:resolve

Traverse a folder (for folders only).

SELECT

xdb:unlink

Allow deletion of links from a resource.

DELETE

xdb:unlink-from

Allow deletion of links to a resource.

N/A

xdb:update-acl

Change the contents of the resource ACL.

UPDATE

xdb:write-acl-ref

Change the ACLOID of a resource.

UPDATE

Aggregate Privileges
Table 27–3 lists the aggregate privileges and the atomic privileges of which each is
composed.

Table 27–3

Aggregate Privileges

Aggregate Privilege Component Atomic Privileges
DAV::all

All atomic DAV privileges.

xdb:all

All atomic DAV privileges plus xdb:link-to.

DAV::bind

xdb:link

DAV::unbind

xdb:unlink

DAV::read

xdb:read-properties, xdb:read-contents, xdb:resolve

DAV::read-acl

xdb:read-acl

DAV::write

DAV::write-content, DAV::write-properties, xdb:link,
xdb:unlink, xdb:unlink-from

DAV::write-acl

xdb:write-acl-ref, xdb:update-acl

DAV::update

DAV::write-content, DAV::write-properties

xdb:update

DAV::write-properties, DAV::write-content

ACLs and ACEs
An access control list (ACL) is a standard security mechanism that is used in some
languages, such as Java, and some operating systems, such as Microsoft Windows.
ACLs are also a part of the WebDAV standard. ACLs are used to protect resources,
which in the case of Oracle Database can be either resources (files and folders) in
Oracle XML DB Repository.
Repository resources can be accessed using WebDAV, and their protecting ACLs act as
WebDAV ACLs. Each repository resource is protected by some ACL. ACLs that protect
a resource are enforced no matter how the resource is accessed, whether by WebDAV,
SQL, or any other way.
When a new resource is created in Oracle XML DB Repository, by default the ACL on
its parent folder is used to protect the resource. After the resource is created, a new
ACL can be set on it.

27-6 Oracle XML DB Developer's Guide

ACLs and ACEs

ACLs in Oracle Database are XML documents that are validated against the Oracle
Database ACL XML schema, which is located in Oracle XML DB Repository at
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/acl.xsd. ACLs are
themselves stored and managed as resources in the repository.
Before a principal performs an operation on ACL-protected data, the user privileges
for the protected data are checked. The set of privileges checked depends on the
operation to be performed.
Aggregate privileges are composed of other privileges. When an ACL is stored, the
aggregate privileges it refers to act as sets of pointers to their component privileges.
All ACLs are stored in table XDB$ACL, which is owned by database user XDB. This is
an XML schema-based XMLType table. Each row in this table (and therefore each ACL)
has a system-generated object identifier (OID) that can be accessed as a column named
OBJECT_ID.
Each Oracle XML DB Repository resource has a property named ACLOID. The ACLOID
stores the OID of the ACL that protects the resource. An ACL is itself a resource, and
the XMLRef property of an ACL, for example, /sys/acls/all_all_acl.xml, is a
REF to the row in table XDB$ACL that contains the content of the ACL. These two
properties form the link between table XDB$RESOURCE, which stores Oracle XML DB
resources, and table XDB$ACL.
See Also:
■

■

Appendix A, "Oracle-Supplied XML Schemas and Examples" for
the ACL XML schema
Oracle Database 2 Day + Security Guide for information about
database schema XDB

System ACLs
Some ACLs are predefined and supplied with Oracle Database. They are referred to as
system ACLs.
There is only one ACL that is self-protected, that is, protected by its own contents. It is
the bootstrap ACL, a system ACL that is located in Oracle XML DB Repository at
/sys/acls/bootstrap_acl.xml. The bootstrap ACL grants READ privilege to all
users. It also grants FULL ACCESS to database roles XDBADMIN (the Oracle XML DB
administrator) and DBA. Database role XDBADMIN is particularly useful for users who
must register global XML schemas.
Other system ACLs include the following. Each is protected by the bootstrap ACL.
■

all_all_acl.xml – Grants all privileges to all users.

■

all_owner_acl.xml – Grants all privileges to the owner of the resource.

■

ro_all_acl.xml – Grants read privileges to all users.

System ACLs use the file-naming convention __acl.xml,
where  represents the privilege granted, and  represents the
users that are granted access to the resource. When you define your own ACLs, you
can use any names you like.
See Also:

"Local and Global XML Schemas" on page 7-14

Repository Access Control 27-7

ACLs and ACEs

ACL and ACE Evaluation
Privileges are checked before a principal is allowed to access a repository resource that
is protected by one or more ACLs. This check is done by evaluating the protecting
ACLs for that principal, in order. For each such ACL, the ACEs in it that apply to the
principal are examined, in order.
If one ACE grants a certain privilege to the current user and another ACE denies that
privilege to the user, then a conflict arises. There are two possible ways to manage
conflicts among ACEs for the same principal.
■

■

The default behavior, termed ace-order, is to use only the first ACE that occurs
for a given principal. Additional ACEs for that principal have no effect. In this
case, ACE order is relevant.
You can, however, configure the database to use an alternate behavior,
deny-trumps-grant. In this case, any ACE with child deny for a given
principal denies permission to that principal, whether or not there are other ACEs
for that principal that have a grant child. In this case, deny always takes
precedence over grant, and ACE order is irrelevant.

You can configure ACL evaluation behavior by setting configuration parameter
acl-evaluation-method, in configuration file xdbconfig.xml, to either
ace-order or deny-trumps-grant. The default configuration file specifies
ace-method, but the default value for element acl-evaluation-method, used
when no method is given, is deny-trumps-grant.
Note: In releases prior to Oracle Database 11g Release 1, only one
ACL evaluation behavior was available: deny-trumps-grant
(though it was not specified in the configuration file).

The change to use ace-order as the default behavior has important
consequences for upgrading and downgrading between database
versions. See "Upgrading an Existing Oracle XML DB Installation" on
page 34-3.

ACL Validation
When an ACL is created, it is validated against the XML schema for ACLs, and some
correctness tests are run, such as ensuring that start and end dates for ACEs are in
chronological order. There is no complete check at ACL creation time of relations
among ACLs. For example, no check is made for the existence and correctness of a
parent ACL. (See "ACL Inheritance" on page 27-9.)
Such a complete check of ACL correctness is called ACL validity checking, but it is not
to be confused with its XML schema validity. For an ACL to be valid (as an ACL), it
must also be XML schema-valid, but the converse does not hold.
A full ACL validity check is made at run time, whenever an ACL is evaluated to check
whether a principal has the proper privileges for some operation. If this check finds
that the ACL is invalid, then all privileges that the ACL would grant are denied to the
specified principals.
ACL validity can also be checked independently of its run-time use to check
privileges, by invoking PL/SQL procedure DBMS_XDBZ.validateACL. You can do
this ahead of time, to avoid run-time errors or privilege denial due to ACL invalidity.

27-8 Oracle XML DB Developer's Guide

ACLs and ACEs

ACL Inheritance
An ACL can inherit grants, that is, associations of principals with privileges, from
another ACL. Inheritance provides flexibility of definition and promotes reuse of
access control policies.
Grants are defined in ACEs, so inheritance of grants involves traversing ACL
inheritance chains and the associated ACES. But ACL inheritance, and therefore grant
inheritance, can be recursive. If ACL A1 inherits from ACL A2, a grant defined by A1 is
not necessarily present in an ACE of A2. It might instead be in an ACE in ACL A3,
where A2 inherits (directly or indirectly) from A3.
ACL inheritance is simple, not multiple, inheritance: an ACL inherits from at most one
other ACL. Cycles are not permitted in an inheritance chain: an ACL that inherits
directly or indirectly from itself is invalid. An ACL that inherits from an ACL that does
not exist is also invalid.
The grants declared in an ACL are those explicitly defined by its ACES. The grants
defined for an ACL are those defined by its ACES plus those inherited by it.
There are two kinds of ACL inheritance, extending inheritance and constraining
inheritance, specified using element extends-from or element constrained-with,
respectively. Both elements reference the ACL being inherited from. An ACL can have
at most one extends-from or constrained-with element. Example 27–3 shows an
extends-from element. Example 27–4 shows a constrained-with element.
Example 27–3

Element extends-from


Example 27–4

Element constrained-with



Extending inheritance extends the grants that are declared in the inheriting ACL (the
child ACL) by some grants that are defined for the ACL it is inheriting from (the
parent ACL). For example, if ACL A1 declares that it extends from ACL A2, then A1
can include grants defined for A2.
Constraining inheritance restricts the grants that are declared in the inheriting ACL to
grants that are also defined for the ACL it is inheriting from. For example, if ACL A1
declares that it inherits from ACL A2 by constraining, then all grants defined for A1
must also be defined for A2.
Extending inheritance is a set union operation, and constraining inheritance is a set
intersection operation. When ACL A1 extends from ACL A2, the grants in both can be
combined to determine whether a given principal is granted a given privilege. When
ACL A1 is constrained with ACL A2, only the grants that are common to both A1 and
A2 are used to determine a grant.
More precisely, when ACL A1 inherits from ACL A2, and A1 is checked to see if a
given principal has been granted a given set of privileges, determination proceeds as
follows:
■

If A1 extends from A2 – The ACEs that are declared in A1 are examined first. If
they do not grant all or deny any of the privileges in question to the principal, then
the ACEs defined in the extending-from parent of A1 are examined. This in
turn means that if the ACEs that are explicitly declared in A2 do not grant all or
deny any of the privileges in question to the principal, and if A2 extends from A3,
then A3 is examined. And so on.

Repository Access Control 27-9

ACLs and ACEs

■

If A1 is constrained with A2 – The ACEs that are explicitly declared in A1 and
those defined for A2 are each examined separately to ensure that they both grant
all of the privileges in question to the specified principal. The check for A2
proceeds the same way if it is constrained by ACL A3, and so on.

Put another way, extending inheritance accumulates granted privileges and
constraining inheritance accumulates denied privileges. In extending inheritance, if
either the child or the parent ACL grants a privilege to the principal, then the privilege
is granted. In constraining inheritance, if either the child or the parent ACL denies a
privilege, then it is denied.
See Also: Example 27–5 on page 27-10 for an ACL that uses
extending inheritance

Complementing the Principals in an ACE: Element invert
It is sometimes more convenient to define a set of principals by complementing
another set of principals—that is the purpose of ACE element invert. Instead of
listing each of the principals that you want to include, wrap the list of principals that
you want to exclude with element invert.
In Example 27–5, the first ACE denies privilege privilege1 to all principals except
IntranetUsers. Because (by default) ACEs are considered in the order they appear,
all subsequent ACEs are overridden by the first ACE, so principal NonIntraNetUser
is denied privilege privilege1 in spite of the explicit grant.
Example 27–5

Complementing a Set of Principals with Element invert




false
dav:owner



true
GERONIMO




ACE Validity Time Period
You can use optional attributes start_date and end_date (of XML Schema type
dateTime) to define the time period over which an ACE is valid. If start_date is
specified, then the ACE is valid on and after that date. If end_date is specified, then
the ACS is invalid after that date. The end_date value must follow the start_date
chronologically or else be the same value. Otherwise, the ACE and its ACL are invalid.
If no time zone is specified in an XML Schema dateTime value, then GMT (UTC) is
assumed. Example 27–6 shows an ACE with start and end dates.

27-10 Oracle XML DB Developer's Guide

Working with Access Control Lists (ACLs)

Example 27–6

ACE with Start and End Dates


true
GERONIMO



Working with Access Control Lists (ACLs)
Oracle Database access control lists (ACLs) are themselves (file) resources in Oracle
XML DB Repository, so all of the access methods that operate on repository resources
also apply to ACLs. In addition, there are several APIs specific to ACLs in package
DBMS_XDB. Those procedures and functions let you use PL/SQL to access Oracle
XML DB security mechanisms, check user privileges based on a particular ACL, and
list the set of privileges the current user has for a particular ACL and resource.
See Also:

Chapter 34, "Administering Oracle XML DB"

Creating an ACL using DBMS_XDB.CREATERESOURCE
Example 27–7 creates an ACL as file resource /TESTUSER/acl1.xml. If applied to a
resource, this ACL grants all privileges to the owner of the resource.
Example 27–7

Creating an ACL using CREATERESOURCE

DECLARE
b BOOLEAN;
BEGIN
b := DBMS_XDB.createFolder('/TESTUSER');
b := DBMS_XDB.createResource(
'/TESTUSER/acl1.xml',
'

true
dav:owner




',
'http://xmlns.oracle.com/xdb/acl.xsd',
'acl');
END;

Before performing any operation that uses an ACL file
resource that was created during the current transaction, you must
perform a COMMIT operation. Until you do that, an ORA-22881
"dangling REF" error is raised whenever you use the ACL file.

Note:

Repository Access Control 27-11

Working with Access Control Lists (ACLs)

Retrieving an ACL Document, Given its Repository Path
Example 27–8 shows how to retrieve an ACL document, given its location in Oracle
XML DB Repository.
Example 27–8

Retrieving an ACL Document, Given its Repository Path

SELECT a.OBJECT_VALUE FROM RESOURCE_VIEW rv, XDB.XDB$ACL a
WHERE ref(a)
= XMLCast(XMLQuery('declare default element namespace
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
fn:data(/Resource/XMLRef)'
PASSING rv.RES RETURNING CONTENT)
AS REF XMLType)
AND equals_path(rv.RES, '/TESTUSER/acl1.xml') = 1;
OBJECT_VALUE
-------------------------------------------------------------------------------

true
dav:owner






Setting the ACL of a Resource
Example 27–9 creates resource /TESTUSER/po1.xml and sets its ACL to
/TESTUSER/acl1.xml using PL/SQL procedure DBMS_XDB.setACL.
Example 27–9

Setting the ACL of a Resource

DECLARE
b BOOLEAN;
BEGIN
b := DBMS_XDB.createResource('/TESTUSER/po1.xml', 'Hello');
END;
/
CALL DBMS_XDB.setACL('/TESTUSER/po1.xml', '/TESTUSER/acl1.xml');

Deleting an ACL
Example 27–10 illustrates how to delete an ACL using procedure DBMS_
XDB.deleteResource. It deletes the ACL created in Example 27–7.
Example 27–10 Deleting an ACL
CALL DBMS_XDB.deleteResource('/TESTUSER/acl1.xml');

If a resource is being protected by an ACL that you want to delete, change the ACL of
that resource before deleting the ACL.

27-12 Oracle XML DB Developer's Guide

Working with Access Control Lists (ACLs)

Updating an ACL
You can update an ACL using any of the standard ways of updating resources. In
particular, since an ACL is an XML document, you can use Oracle SQL function
updateXML and related XML-updating functions to manipulate ACLs. You must
COMMIT after making any ACL changes.
Oracle XML DB ACLs are cached, for fast evaluation. When a transaction that updates
an ACL is committed, the modified ACL is picked up by existing database sessions,
after the timeout specified in the Oracle XML DB configuration file,
/xdbconfig.xml. The XPath location for this timeout parameter is
/xdbconfig/sysconfig/acl-max-age. The value is expressed in seconds.
Sessions initiated after the ACL is modified use the new ACL without any delay.
If an ACL resource is updated with non-ACL content, the same rules apply as for
deletion. Thus, if any resource is being protected by an ACL that is being updated, you
must first change the ACL.
See Also: "Updating XML Data" on page 4-10 for information about
the Oracle SQL functions used here to update XML data

You can use FTP or WebDAV to update an ACL. For more details on how to use these
protocols, see Chapter 28, "Accessing the Repository using Protocols". You can update
an ACL or an access control entry (ACE) using RESOURCE_VIEW.
Example 27–11 uses Oracle SQL function updateXML to update the ACL
/TESTUSER/acl1.xml by replacing it entirely. The effect is to replace the principal
value DAV::owner by TESTUSER, because the rest of the replacement ACL is the
same as it was before.
Example 27–11 Updating (Replacing) an Access Control List
UPDATE RESOURCE_VIEW r
SET r.RES =
updateXML(
r.RES,
'/r:Resource/r:Contents/a:acl',
'

true
TESTUSER




',
'xmlns:r="http://xmlns.oracle.com/xdb/XDBResource.xsd"
xmlns:a="http://xmlns.oracle.com/xdb/acl.xsd"')
WHERE equals_path(r.RES, '/TESTUSER/acl1.xml') = 1;

Example 27–12 uses Oracle SQL function appendChildXML to append an ACE to an
existing ACL. The ACE gives privileges read-properties and read-contents to
user HR.

Repository Access Control 27-13

Working with Access Control Lists (ACLs)

Example 27–12 Appending ACEs to an Access Control List
UPDATE RESOURCE_VIEW r
SET r.RES =
appendChildXML(
r.RES,
'/r:Resource/r:Contents/a:acl',
XMLType('
true
HR




'),
'xmlns:r="http://xmlns.oracle.com/xdb/XDBResource.xsd"
xmlns:a="http://xmlns.oracle.com/xdb/acl.xsd"')
WHERE equals_path(r.RES, '/TESTUSER/acl1.xml') = 1;

Example 27–13 uses Oracle SQL function deleteXML to delete an ACE from an ACL.
The first ACE is deleted.
Example 27–13 Deleting an ACE from an Access Control List
UPDATE RESOURCE_VIEW r
SET r.RES =
deleteXML(r.RES,
'/r:Resource/r:Contents/a:acl/a:ace[1]',
'xmlns:r="http://xmlns.oracle.com/xdb/XDBResource.xsd"
xmlns:a="http://xmlns.oracle.com/xdb/acl.xsd"')
WHERE equals_path(r.RES, '/TESTUSER/acl1.xml') = 1;

Retrieving the ACL Document that Protects a Given Resource
Example 26–2 illustrates how to use function DBMS_XDB.getACLDocument to
retrieve the ACL document that protects a given resource.
Example 27–14 Retrieving the ACL Document for a Resource
SELECT XMLSerialize(DOCUMENT DBMS_XDB.getACLDocument('/TESTUSER/po1.xml')
AS CLOB)
FROM DUAL;
XMLSERIALIZE(DOCUMENTDBMS_XDB.GETACLDOCUMENT('/TESTUSER/PO1.XML')ASCLOB)
-------------------------------------------------------------------------------

true
TESTUSER





true
HR


27-14 Oracle XML DB Developer's Guide

Working with Access Control Lists (ACLs)





1 row selected.

See Also: Example 26–2, "Using DBMS_
XDB.GETACLDOCUMENT" on page 26-4

Retrieving Privileges Granted to the Current User for a Particular Resource
Example 27–15 illustrates how to retrieve privileges granted to the current user using
function DBMS_XDB.getPrivileges.
Example 27–15 Retrieving Privileges Granted to the Current User for a Particular
Resource
SELECT XMLSerialize(DOCUMENT DBMS_XDB.getPrivileges('/TESTUSER/po1.xml')
AS CLOB)
FROM DUAL;
XMLSERIALIZE(DOCUMENTDBMS_XDB.GETPRIVILEGES('/TESTUSER/PO1.XML')ASCLOB)
-------------------------------------------------------------------------------



















1 row selected.

Checking Whether the Current User Has Privileges on a Resource
Example 27–16 illustrates how to use function DBMS_XDB.checkPrivileges to
check whether the current user has a given set of privileges on a resource. This
function returns a nonzero value if the user has the privileges.
Example 27–16 Checking If a User Has a Certain Privileges on a Resource
SELECT DBMS_XDB.checkPrivileges(
'/TESTUSER/po1.xml',

Repository Access Control 27-15

Working with Access Control Lists (ACLs)

XMLType('


'))
FROM DUAL;
DBMS_XDB.CHECKPRIVILEGES('/TESTUSER/PO1.XML',
--------------------------------------------1
1 row selected.

Example 27–16 checks to see if the access privileges read-contents and
read-properties have been granted to the current user on resource
/TESTUSER/po1.xml. The positive-integer return value shows that they have.

Checking Whether a User Has Privileges using the ACL and Resource Owner
Function DBMS_XDB.ACLCheckPrivileges is typically used by applications that
must perform ACL evaluation on their own, before allowing a user to perform an
operation.
Example 27–17 checks whether the ACL /TESTUSER/acl1.xml grants the privileges
read-contents and read-properties to the current user, sh. The second
argument, TESTUSER, is the user that is substituted for DAV::owner in the ACL when
checking. Since user sh does not match any of the users granted the specified
privileges, the return value is zero.
Example 27–17 Checking User Privileges using ACLCheckPrivileges
CONNECT sh
Enter password: 
Connected.
SELECT DBMS_XDB.ACLCheckPrivileges(
'/TESTUSER/acl1.xml',
'TESTUSER',
XMLType('


'))
FROM DUAL;
DBMS_XDB.ACLCHECKPRIVILEGES('/TESTUSER/ACL1.XML','TESTUSER',
-----------------------------------------------------------0
1 row selected.

27-16 Oracle XML DB Developer's Guide

Working with Access Control Lists (ACLs)

Retrieving the Path of the ACL that Protects a Given Resource
Example 27–18 retrieves the path of the ACL that protects a given resource, by using a
RESOURCE_VIEW query. The query uses the fact that the XMLRef and ACLOID
elements of the resource form the link between an ACL and a resource.
Example 27–18 Retrieving the Path of the ACL that Protects a Given Resource
SELECT rv1.ANY_PATH
FROM RESOURCE_VIEW rv1
WHERE
XMLCast(XMLQuery('declare default element namespace
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
fn:data(/Resource/XMLRef)'
PASSING rv1.RES RETURNING CONTENT)
AS REF XMLType)
= make_ref(XDB.XDB$ACL,
(SELECT XMLCast(XMLQuery('declare default element namespace
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
fn:data(/Resource/ACLOID)'
PASSING rv2.RES RETURNING CONTENT)
AS REF XMLType)
FROM RESOURCE_VIEW rv2
WHERE equals_path(rv2.RES, '/TESTUSER/po1.xml') = 1));
ANY_PATH
-----------------/TESTUSER/acl1.xml

Example 27–18 retrieves the path to an ACL, given a resource protected by the ACL.
The ACLOID of a protected resource (r) stores the OID of the ACL resource (a) that
protects it. The REF of the ACL resource is the same as that of the object identified by
the protected-resource ACLOID.
The REF of the resource ACLOID can be obtained using Oracle SQL function make_
ref, which returns a REF to an object-table row with a given OID.
In this example, make_ref returns a REF to the row of table XDB$ACL whose OID is
the /Resource/ACLOID for the resource /TESTUSER/po1.xml. The inner query
returns the ACLOID of the resource. The outer query returns the path to the
corresponding ACL.

Retrieving the Paths of All Resources Protected by a Given ACL
Example 27–19 retrieves the paths of all resources protected by a given ACL.
Example 27–19 Retrieving the Paths of All Resources Protected by a Given ACL
SELECT rv1.ANY_PATH
FROM RESOURCE_VIEW rv1
WHERE make_ref(XDB.XDB$ACL,
XMLCast(XMLQuery('declare default element namespace
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
fn:data(/Resource/ACLOID)'
PASSING rv1.RES RETURNING CONTENT)
AS REF XMLType))
= (SELECT XMLCast(XMLQuery('declare default element namespace
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
fn:data(/Resource/XMLRef)'
PASSING rv2.RES RETURNING CONTENT)

Repository Access Control 27-17

ACL Caching

AS REF XMLType)
FROM RESOURCE_VIEW rv2
WHERE equals_path(rv2.RES, '/TESTUSER/acl1.xml') = 1);
ANY_PATH
----------------/TESTUSER/po1.xml
1 row selected.

Example 27–19 retrieves the paths to the resources whose ACLOID REF matches the
REF of the ACL resource whose path is /TESTUSER/acl1.xml. Function make_ref
returns the resource ACLOID REF.
The inner query retrieves the REF of the specified ACL. The outer query selects the
paths of the resources whose ACLOID REF matches the REF of the specified ACL.

ACL Caching
Since ACLs are checked for each access to the data they protect, the performance of the
ACL check operation is critical to the performance of such data, including Oracle
XML DB Repository resources. In Oracle XML DB, the required performance for this
repository operation is achieved by employing several caches.
ACLs are saved in a cache that is shared by all sessions in the database instance. When
an ACL is updated, its entry in the cache is invalidated, together with all objects
dependent on it. The next time the ACL is used, a new copy of it is brought into the
cache. Oracle recommends that you share ACLs among resources as much as possible.
There is a session-specific cache of privileges granted to a given user by a given ACL.
The entries in this cache have a time out (in seconds) specified by the element
 in the Oracle XML DB configuration file (/xdbconfig.xml). For
maximum performance, set this timeout as large as possible. But note that there is a
trade-off here: the greater the timeout, the longer it takes for current sessions to pick
up an updated ACL.
Oracle XML DB also maintains caches to improve performance when using ACLs that
have LDAP principals (LDAP groups or users). The goal of these caches is to minimize
network communication with the LDAP server. One is a shared cache that maps LDAP
GUIDs to the corresponding LDAP nicknames and Distinguished Names (DNs). This
is used when an ACL document is being displayed (or converted to CLOB or
VARCHAR2 values from an XMLType instance). To purge this cache, use procedure
DBMS_XDBZ.purgeLDAPCache. The other cache is session-specific and maps LDAP
groups to their members (nested membership). Note that whenever Oracle XML DB
encounters an LDAP group for the first time (in a session) it gets the nested
membership of that group from the LDAP server. Hence it is best to use groups with
as few members and levels of nesting as possible.

Repository Resources and Database Table Security
Resources in Oracle XML DB Repository are of two types:
■

■

LOB-based (content is stored in a LOB which is part of the resource). Access is
determined only by the ACL that protects the resource.
REF-based (content is XML and is stored in a database table). Users must have the
appropriate privilege for the underlying table or view where the XML content is
stored in addition to ACL permissions for the resource.

27-18 Oracle XML DB Developer's Guide

Repository Resources and Database Table Security

Since the content of a REF-based resource can be stored in a table, it is possible to
access this data directly using SQL queries on the table. A uniform access control
mechanism is one where the privileges needed for access are independent of the
method of access (for example, FTP, HTTP, or SQL). To provide a uniform security
mechanism using ACLs, the underlying table must first be hierarchy-enabled, before
resources that reference the rows in the table are inserted into Oracle XML DB.
The default tables produced by XML schema registration are hierarchy-enabled.
Enabling hierarchy is the default behavior when you register an XML schema with
Oracle XML DB. You can also enable hierarchy after registration, using procedure
DBMS_XDBZ.enable_hierarchy.
Enabling hierarchy on a resource table does the following:
■

■

■

Adds two hidden columns to store the ACLOID and the OWNER of the resources
that reference the rows in the table.
Adds a row-level security (RLS) policy to the table, which checks the ACL
whenever a SELECT, UPDATE, or DELETE operation is executed on the table.
Creates a database trigger, called the path-index trigger, that ensures that the
last-modified information for a resource is updated whenever the corresponding
row is updated in the XMLType table where the content is stored.
See Also:
■

■

Oracle Database PL/SQL Packages and Types Reference for
information about procedure DBMS_
XMLSCHEMA.registerSchema
Oracle Database PL/SQL Packages and Types Reference for
information about procedure DBMS_XDBZ.enable_hierarchy

In any given table, it is possible that only some of the objects are mapped to Oracle
XML DB resources. Only those objects that are mapped undergo ACL checking, but all
of the objects have table-level security.
You cannot hide data in XMLType tables from other users if
out-of-line storage of is used. Out-of-line data is not protected by
ACL security.
Note:

Optimization: Do not enforce acl-based security if you do not need it
ACL-based security provides control of access to XML content
document-by-document, rather than just table-by-table. When you call PL/SQL
procedure DBMS_XMLSCHEMA.register_chema, the tables it creates have
ACL-based security enabled, by default.
One effect of this is that when the XML content of such a table is accessed using a SQL
statement, a call to sys_checkACL is automatically added to the query WHERE clause,
to ensure that the ACL security that was defined is enforced at the SQL level.
Enforcing ACL-based security adds overhead to the SQL query, however. If
ACL-based security is not required, then use procedure disable_hierarchy in
package DBMS_XDBZ to turn off ACL checking.
When ACL-based security is enabled for an XMLType table, the execution plan output
for a query of that table contains a filter similar to the following:
3 - filter(SYS_CHECKACL("ACLOID","OWNERID",xmltype(''
''))=1)

In this example, the filter checks that the user performing the SQL query has
read-contents privilege on each of the documents to be accessed.
After calling DBMX_XDBZ.disable_hierarchy, an execution plan of the same
query does not show SYS_CHECKACL in the filter.
See Also: Oracle Database PL/SQL Packages and Types Reference for
information about procedure DBMS_XDBZ.disable_hierarchy

Integrating Oracle XML DB with LDAP
This section discusses allowing LDAP users to use the features of Oracle XML DB,
including ACLs. The typical scenario is a single, shared database schema (user), to
which multiple LDAP users are mapped. This mapping is maintained in the Oracle
Internet Directory. End users can log into the database using their LDAP username
and password. They are then automatically mapped to the corresponding shared
database schema. (Users can log in using SQL or any of the supported Oracle XML DB
protocols.) The implicit ACL resolution is based on the current LDAP user and the
corresponding LDAP group membership information.
Before you can use LDAP users and groups as principals in Oracle XML DB ACLs, the
following prerequisites must be satisfied:
■

■

■
■

■
■

An Oracle Internet Directory must be set up, and the database must be registered
with it.
SSL authentication must be set up between the database and the Oracle Internet
Directory.
A database user must be created that corresponds to the shared database schema.
The LDAP users must be created and mapped in the Oracle Internet Directory to
the shared database schema.
The LDAP groups must be created and their members must be specified.
ACLs must be defined for the LDAP groups and users, and they must be used to
protect the repository resources to be accessed by the LDAP users.
See Also:
■
■

■

Oracle Internet Directory Administrator's Guide
Oracle Database Advanced Security Administrator's Guide for
information about setting up SSL authentication
Oracle Database Enterprise User Security Administrator's Guide for
information about using shared database schemas for enterprise
(LDAP) users

Example 27–20 shows an ACL for an LDAP user. Element  contains the
full distinguished name of the LDAP user – in this case,
cn=user1,ou=Americas,o=oracle,l=redwoodshores,st=CA,c=US.

27-20 Oracle XML DB Developer's Guide

Integrating Oracle XML DB with LDAP

Example 27–20 ACL Referencing an LDAP User


true
cn=user1,ou=Americas,o=oracle,l=redwoodshores,st=CA,c=US







See Also: Oracle Internet Directory Administrator's Guide for the
format of an LDAP user distinguished name

Example 27–21 shows an ACL for an LDAP group. Element  contains
the full distinguished name of the LDAP group.
Example 27–21 ACL Referencing an LDAP Group


true
cn=grp1,ou=Americas,o=oracle,l=redwoodshores,st=CA,c=US






See Also: Oracle Internet Directory Administrator's Guide for the
format of an LDAP group distinguished name

Repository Access Control 27-21

Integrating Oracle XML DB with LDAP

27-22 Oracle XML DB Developer's Guide

28
Accessing the Repository using Protocols
This chapter describes how to access Oracle XML DB Repository data using FTP,
HTTP(S)/WebDAV protocols.
This chapter contains these topics:
■

Overview of Oracle XML DB Protocol Server

■

Oracle XML DB Protocol Server Configuration Management

■

Using FTP and Oracle XML DB Protocol Server

■

Using HTTP(S) and Oracle XML DB Protocol Server

■

Using WebDAV and Oracle XML DB

Overview of Oracle XML DB Protocol Server
As described in Chapter 2, "Getting Started with Oracle XML DB" and Chapter 21,
"Accessing Oracle XML DB Repository Data", Oracle XML DB Repository provides a
hierarchical data repository in the database, designed for XML. Oracle XML DB
Repository maps path names (or URLs) onto database objects of XMLType and
provides management facilities for these objects.
Oracle XML DB also provides the Oracle XML DB protocol server. This supports
standard Internet protocols, FTP, WebDAV, and HTTP(S), for accessing its hierarchical
repository or file system. Note that HTTPS provides secure access to Oracle XML DB
Repository.
These protocols can provide direct access to Oracle XML DB for many users without
having to install additional software. The user names and passwords to be used with
the protocols are the same as those for SQL*Plus. Enterprise users are also supported.
Database administrators can use these protocols and resource APIs such as DBMS_XDB
to access Oracle Automatic Storage Management (Oracle ASM) files and folders in the
repository virtual folder /sys/asm.
See Also: Chapter 21, "Accessing Oracle XML DB Repository
Data" for more information about accessing repository information,
and restrictions on that access

Accessing the Repository using Protocols 28-1

Overview of Oracle XML DB Protocol Server

Note:
■

■

When accessing virtual folder /sys/asm using Oracle XML DB
protocols, you must log in with the privileges of role DBA but as
a user other than SYS.
Oracle XML DB protocols are not supported on EBCDIC
platforms.

Session Pooling
Oracle XML DB protocol server maintains a shared pool of sessions. Each protocol
connection is associated with one session from this pool. After a connection is closed
the session is put back into the shared pool and can be used to serve later connections.
Session pooling improves performance of HTTP(S) by avoiding the cost of re-creating
session states, especially when using HTTP 1.0, which creates new connections for
each request. For example, a couple of small files can be retrieved by an existing
HTTP/1.1 connection in the time necessary to create a database session. You can tune
the number of sessions in the pool by setting session-pool-size in Oracle XML DB
xdbconfig.xml file, or disable it by setting pool size to zero.
Session pooling can affect users writing Java servlets, because other users can see
session state initialized by another request for a different user. Hence, servlet writers
should only use session memory, such as Java static variables, to hold data for the
entire application rather than for a particular user. State for each user must be stored in
the database or in a lookup table, rather than assuming that a session only exists for a
single user.
See Also: Chapter 32, "Writing Oracle XML DB Applications in
Java"

Figure 28–1 illustrates the Oracle XML DB protocol server components and how they
are used to access files in Oracle XML DB Repository and other data. Only the relevant
components of the repository are shown
Figure 28–1 Oracle XML DB Architecture: Protocol Server
Oracle XML DB Repository

FTP
Client

FTP
Server

Network
HTTP
WebDAV
Client

Protocol
Server

Foldering

Configuration
Management
HTTP /
WebDAV
Server
ACL
Security

28-2 Oracle XML DB Developer's Guide

Oracle XML DB Protocol Server Configuration Management

Oracle XML DB Protocol Server Configuration Management
Oracle XML DB protocol server uses configuration parameters stored in
/xdbconfig.xml to initialize its startup state and manage session level
configuration. The following section describes the protocol-specific configuration
parameters that you can configure in the Oracle XML DB configuration file. The
session pool size and timeout parameters cannot be changed dynamically, that is, you
must restart the database in order for these changes to take effect.
See Also: "Configuring Oracle XML DB using xdbconfig.xml" on
page 34-5

Configuring Protocol Server Parameters
Figure 28–1 shows the parameters common to all protocols. All parameter names in
this table, except those starting with /xdbconfig, are relative to the following XPath
in the Oracle XML DB configuration schema:
/xdbconfig/sysconfig/protocolconfig/common
■

FTP-specific parameters – Table 28–2 shows the FTP-specific parameters. These are
relative to the following XPath in the Oracle XML DB configuration schema:
/xdbconfig/sysconfig/protocolconfig/ftpconfig

■

HTTP(S)/WebDAV specific parameters, except servlet-related parameters – Table 28–3
shows the HTTP(S)/WebDAV-specific parameters. These parameters are relative
to the following XPath in the Oracle XML DB configuration schema:
/xdbconfig/sysconfig/protocolconfig/httpconfig

See Also:
■

■

■

■

Chapter 34, "Administering Oracle XML DB" for more information
about the configuration file xdbconfig.xml
"xdbconfig.xsd: XML Schema for Configuring Oracle XML DB" on
page A-16
"Configuring Default Namespace to Schema Location Mappings"
on page 34-10 for more information about the
schemaLocation-mappings parameter
"Configuring XML File Extensions" on page 34-12 for more
information about the xml-extensions parameter

For examples of the usage of these parameters, see the configuration file,
xdbconfig.xml.
Table 28–1

Common Protocol Configuration Parameters

Parameter

Description

extension-mappings/mime-mappings

Specifies the mapping of file
extensions to mime types. When a
resource is stored in Oracle XML DB
Repository, and its mime type is not
specified, this list of mappings is
used to set its mime type.

Accessing the Repository using Protocols 28-3

Oracle XML DB Protocol Server Configuration Management

Table 28–1 (Cont.) Common Protocol Configuration Parameters
Parameter

Description

extension-mappings/lang-mappings

Specifies the mapping of file
extensions to languages. When a
resource is stored in Oracle XML DB
Repository, and its language is not
specified, this list of mappings is
used to set its language.

extension-mappings/encoding-mappings

Specifies the mapping of file
extensions to encodings. When a
resource is stored in Oracle XML DB
Repository, and its encoding is not
specified, this list of mappings is
used to set its encoding.

xml-extensions

Specifies the list of filename
extensions that are treated as XML
content by Oracle XML DB.

session-pool-size

Maximum number of sessions that
are kept in the protocol server
session pool

/xdbconfig/sysconfig/call-timeout

If a connection is idle for this time
(in hundredths of a second), then
the shared server serving the
connection is freed up to serve other
connections.

session-timeout

Time (in hundredths of a second)
after which a session (and
consequently the corresponding
connection) is terminated by the
protocol server if the connection has
been idle for that time. This
parameter is used only if the specific
protocol session timeout is not
present in the configuration

schemaLocation-mappings

Specifies the default schema
location for a given namespace. This
is used if the instance XML
document does not contain an
explicit xsi:schemaLocation
attribute.

/xdbconfig/sysconfig/default-lock-timeout

Time period after which a WebDAV
lock on a resource becomes invalid.
This could be overridden by a
Timeout specified by the client that
locks the resource.

Table 28–2

Configuration Parameters Specific to FTP

Parameter

Description

buffer-size

Size of the buffer, in bytes, used to read data from the
network during an FTP put operation. Set
buffer-size to larger values for higher put
performance. There is a trade-off between put
performance and memory usage. The value can be from
1024 to 1048496, inclusive. The default value is 8192.

28-4 Oracle XML DB Developer's Guide

Oracle XML DB Protocol Server Configuration Management

Table 28–2 (Cont.) Configuration Parameters Specific to FTP
Parameter

Description

ftp-port

Port on which FTP server listens. By default, this is 0,
which means that FTP is disabled. FTP is disabled by
default because the FTP specification requires that
passwords be transmitted in clear text, which can
present a security hazard. To enable FTP, set this
parameter to the FTP port to use, such as 2100.

ftp-protocol

Protocol over which the FTP server runs. By default,
this is tcp.

ftp-welcome-message

A user-defined welcome message that is displayed
whenever an FTP client connects to the server. If this
parameter is empty or missing, then the following
default welcome message is displayed: "Unauthorized
use of this FTP server is prohibited and may be subject
to civil and criminal prosecution."

session-timeout

Time (in hundredths of a second) after which an FTP
connection is terminated by the protocol server if the
connection has been idle for that time.

Table 28–3 Configuration Parameters Specific to HTTP(S)/WebDAV (Except Servlet
Parameters)
Parameter

Description

http-port

Port on which the HTTP(S)/WebDAV server
listens, using protocol http-protocol. By
default, this is 0, which means that HTTP is
disabled. If this parameter is empty
(), then the default value of 0
applies. An empty parameter is not
recommended.
This parameter must be present, whether or not
it is empty. Otherwise, validation of
xdbconfig.xml against XML schema
xdbconfig.xsd fails. The value must be
different from the value of http2-port.
Otherwise, an error is raised.

http2-port

Port on which the HTTP(S)/WebDAV server
listens, using protocol http2-protocol.
This parameter is optional, but, if present, then
http2-protocol must also be present.
Otherwise, an error is raised. The value must be
different from the value of http-port.
Otherwise, an error is raised. An empty
parameter () also raises an
error.

http-protocol

Protocol over which the HTTP(S)/WebDAV
server runs on port http-port. Must be either
TCP or TCPS.
This parameter must be present. Otherwise,
validation of xdbconfig.xml against XML
schema xdbconfig.xsd fails. An empty
parameter () also raises an
error.

Accessing the Repository using Protocols 28-5

Oracle XML DB Protocol Server Configuration Management

Table 28–3 (Cont.) Configuration Parameters Specific to HTTP(S)/WebDAV (Except
Servlet Parameters)
Parameter

Description

http2-protocol

Protocol over which the HTTP(S)/WebDAV
server runs on port http2-port. Must be either
TCP or TCPS. If this parameter is empty
(), then the default value
of TCP applies. (An empty parameter is not
recommended.)
This parameter is optional, but, if present, then
http2-port must also be present. Otherwise,
an error is raised.

session-timeout

Time (in hundredths of a second) after which an
HTTP(S) session (and consequently the
corresponding connection) is terminated by the
protocol server if the connection has been idle
for that time.

max-header-size

Maximum size (in bytes) of an HTTP(S) header

max-request-body

Maximum size (in bytes) of an HTTP(S) request
body

webappconfig/welcome-file-list

List of filenames that are considered welcome
files. When an HTTP(S) get request for a
container is received, the server first checks if
there is a resource in the container with any of
these names. If so, then the contents of that file
are sent, instead of a list of resources in the
container.

default-url-charset

The character set in which an HTTP(S) protocol
server assumes incoming URL is encoded when
it is not encoded in UTF-8 or the Content-Type
field Charset parameter of the request.

allow-repository-anonymous-access Indication of whether or not anonymous HTTP
access to Oracle XML DB Repository data is
allowed using an unlocked ANONYMOUS user
account. The default value is false, meaning
that unauthenticated access to repository data is
blocked. See "Anonymous Access to Oracle
XML DB Repository using HTTP" on page 28-17.
HTTP header that specifies the expiration date
and time for a URL. See "Controlling URL
Expiration Time" on page 28-17.

expire

Configuring Secure HTTP (HTTPS)
To enable Oracle XML DB Repository to use secure HTTP connections (HTTPS), a
database administrator (DBA) must configure the database accordingly: configure
parameters http2-port and http2-protocol, enable the HTTP Listener to use
SSL, and enable launching of the TCPS Dispatcher. After doing this, the DBA must
stop, then restart, the database and the listener.
See Also: "Configuring Oracle XML DB using xdbconfig.xml" on
page 34-5 for information about configuring Oracle XML DB
parameters

28-6 Oracle XML DB Developer's Guide

Oracle XML DB Protocol Server Configuration Management

Enable the HTTP Listener to Use SSL
A database administrator must carry out the following steps, to configure the HTTP
Listener for SSL.
Configuring the HTTP Listener for SSL requires that you have
the option Oracle Advanced Security.

Note:

1.

Create a wallet for the server and import a certificate – Use Oracle Wallet Manager to
do the following:
a.

Create a wallet for the server.

b.

If a valid certificate with distinguished name (DN) of the server is not
available, create a certificate request and submit it to a certificate authority.
Obtain a valid certificate from the authority.

c.

Import a valid certificate with the distinguished name (DN) of the server into
the server.

d.

Save the new wallet in obfuscated form, so that it can be opened without a
password.
See Also: Oracle Database Advanced Security Administrator's Guide for
information about how to create a wallet

2.

Specify the wallet location to the server – Use Oracle Net Manager to do this. Ensure
that the configuration is saved to disk. This step updates files sqlnet.ora and
listener.ora.

3.

Disable client authentication at the server, since most Web clients do not have
certificates. Use Oracle Net Manager to do this. This step updates file
sqlnet.ora.

4.

Create a listening end point that uses TCP/IP with SSL – Use Oracle Net Manager to
do this. This step updates file listener.ora.
See Also: Oracle Database Advanced Security Administrator's Guide for
detailed information regarding steps 1 through 4

Enable TCPS Dispatcher
A database administrator must edit the database pfile to enable launching of a TCPS
dispatcher during database startup. The following line must be added to the file,
where SID is the SID of the database:
dispatchers=(protocol=tcps)(service=SIDxdb)

The database pfile location depends on your operating system, as follows:
■

■

MS Windows – PARENT/admin/orcl/pfile, where PARENT is the parent folder
of folder ORACLE_HOME
UNIX, Linux – $ORACLE_HOME/admin/$ORACLE_SID/pfile

Interaction with Oracle XML DB File-System Resources
The protocol specifications, RFC 959 (FTP), RFC 2616 (HTTP), and RFC 2518
(WebDAV) implicitly assume an abstract, hierarchical file system on the server side.
This is mapped to Oracle XML DB Repository. The repository provides:

Accessing the Repository using Protocols 28-7

Using FTP and Oracle XML DB Protocol Server

■
■

■

Name resolution.
Security based on access control lists (ACLs). An ACL is a list of access control
entries that determine which principals have access to a given resource or
resources. See also Chapter 27, "Repository Access Control".
The ability to store and retrieve any content. The repository can store both binary
data input through FTP and XML schema-based documents.
See Also:
■

http://www.ietf.org/rfc/rfc959.txt

■

http://www.ietf.org/rfc/rfc2616.txt

■

http://www.ietf.org/rfc/rfc2518.txt

Protocol Server Handles XML Schema-Based or Non-Schema-Based XML Documents
Oracle XML DB protocol server enhances the protocols by always checking if XML
documents being inserted are based on XML schemas registered in Oracle XML DB
Repository.
■

■

If the incoming XML document specifies an XML schema, then the Oracle
XML DB storage to use is determined by that XML schema. This functionality is
especially useful when you must store XML documents object-relationally in the
database using simple protocols like FTP or WebDAV instead of using SQL
statements.
If the incoming XML document is not XML schema-based, then it is stored as a
binary document.

Event-Based Logging
In certain cases, it may be useful to log the requests received and responses sent by a
protocol server. This can be achieved by setting event number 31098 to level 2. To set
this event, add the following line to your init.ora file and restart the database:
event="31098 trace name context forever, level 2"

Using FTP and Oracle XML DB Protocol Server
The following sections describe FTP features supported by Oracle XML DB.

Oracle XML DB Protocol Server: FTP Features
File Transfer Protocol (FTP) is one of the oldest and most popular protocols on the net.
FTP is specified in RFC959 and provides access to heterogeneous file systems in a
uniform manner. FTP works by providing well-defined commands (methods) for
communication between the client and the server. The transfer of command messages
and the return of status happens on a single connection. However, a new connection is
opened between the client and the server for data transfer. With HTTP(S), commands
and data are transferred using a single connection.
FTP is implemented by dedicated clients at the operating system level, file-system
explorer clients, and browsers. FTP is typically session-oriented: a user session is
created through an explicit logon, a number of files or directories are downloaded and
browsed, and then the connection is closed.

28-8 Oracle XML DB Developer's Guide

Using FTP and Oracle XML DB Protocol Server

Note: For security reasons, FTP is disabled, by default. This is because
the IETF FTP protocol specification requires that passwords be
transmitted in clear text. Disabling is done by configuring the FTP
server port as zero (0). To enable FTP, set the ftp-port parameter to
the FTP port to use, such as 2100.

See Also:
■

■

RFC 959: FTP Protocol Specification –
http://www.ietf.org/rfc/rfc959.txt
"Configuring Oracle XML DB using xdbconfig.xml" on
page 34-5 for information about configuring parameters

FTP Features That Are Not Supported
Oracle XML DB implements FTP, as defined by RFC 959, with the exception of the
following optional features:
■

Record-oriented files, for example, only the FILE structure of the STRU method is
supported. This is the most widely used structure for transfer of files. It is also the
default specified by the specification. Structure mount is not supported.

■

Append.

■

Allocate. This pre-allocates space before file transfer.

■

Account. This uses the insecure Telnet protocol.

■

Abort.

Supported FTP Client Methods
For access to the repository, Oracle XML DB supports the following FTP client
methods.
■

cdup – change working directory to parent directory

■

cwd – change working directory

■

dele – delete file (not directory)

■

list, nlst – list files in working directory

■

mkd – create directory

■

noop – do nothing (but timeout counter on connection is reset)

■

pasv, port – establish a TCP data connection

■

pwd – get working directory

■

quit – close connection and quit FTP session

■

retr – retrieve data using an established connection

■

rmd – remove directory

■

rnfr, rnto – rename file (two-step process: from file, to file)

■

stor – store data using an established connection

■

syst – get system version

■

type – change data type: ascii or image binary types only

Accessing the Repository using Protocols 28-9

Using FTP and Oracle XML DB Protocol Server

■

user, pass – user login
See Also:
■
■

"FTP Quote Methods" for supported FTP quote methods
"Using FTP with Oracle ASM Files" on page 28-11 for an example
of using FTP method proxy

FTP Quote Methods
Oracle Database supports several FTP quote methods, which provide information
directly to Oracle XML DB.
■

rm_r – Remove file or folder . If a folder, recursively remove
all files and folders contained in .
quote rm_r 

■

rm_f – Forcibly remove a resource.
quote rm_f 

■

rm_rf – Combines rm_r and rm_f: Forcibly and recursively removes files and
folders.
quote rm_rf 

■

set_nls_locale – Specify the character-set encoding () to be
used for file and directory names in FTP methods (including names in method
responses).
quote set_nls_locale { | NULL}

Only IANA character-set names can be specified for . If nls_
locale is set to NULL or is not set, then the database character set is used.
■

set_charset – Specify the character set of the data to be sent to the server.
quote set_charset

{ | NULL}

The set_charset method applies to only text files, not binary files, as
determined by the file-extension mapping to MIME types that is defined in
configuration file xdbconfig.xml.
If the parameter provided to set_charset is  (not NULL), then
it specifies the character set of the data.
If the parameter provided to set_charset is NULL, or if no set_charset
command is given, then the MIME type of the data determines the character set for
the data.
–

If the MIME type is not text/xml), then the data is not assumed to be XML.
The database character set is used.

–

If the MIME type is text/xml, then the data represents an XML document.
If a byte order mark1 (BOM) is present in the XML document, then it determines
the character set of the data.
If there is no BOM, then:

1

BOM is a Unicode-standard signature that indicates the order of the stream of bytes that
follows it.

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Using FTP and Oracle XML DB Protocol Server

*

If there is an encoding declaration in the XML document, then it determines
the character set of the data.

*

If there is no encoding declaration, then the UTF-8 character set is used.

Using FTP with Oracle ASM Files
Oracle Automatic Storage Management (Oracle ASM) organizes database files into
disk groups for simplified management and added benefits such as database
mirroring and I/O balancing. Database administrators can use protocols and resource
APIs to access Oracle ASM files in the Oracle XML DB repository virtual folder
/sys/asm. All files in /sys/asm are binary.
Typical uses are listing, copying, moving, creating, and deleting Oracle ASM files and
folders. Example 28–1 is an example of navigating the Oracle ASM virtual folder and
listing the files in a subfolder.
The structure of the Oracle ASM virtual folder, /sys/asm, is described in Chapter 21,
"Accessing Oracle XML DB Repository Data". In Example 28–1, the disk groups are
DATA and RECOVERY; the database name is MFG; and the directories created for aliases
are dbs and tmp. This example navigates to a subfolder, lists its files, and copies a file
to the local file system.
Example 28–1

Navigating Oracle ASM Folders

ftp> open myhost 7777
ftp> user system
Password required for SYSTEM
Password: password
ftp> cd /sys/asm
ftp> ls
DATA
RECOVERY
ftp> cd DATA
ftp> ls
dbs
MFG
ftp> cd dbs
ftp> ls
t_dbl.f
t_axl.f
ftp> binary
ftp> get t_dbl.f, t_axl.f
ftp> put my_db2.f

In Example 28–1, after connecting to and logging onto database myhost (first four
lines), FTP methods cd and ls are used to navigate and list folders, respectively.
When in folder /sys/asm/DATA/dbs, FTP command get is used to copy files t_
db1.f and t_ax1.f to the current folder of the local file system. Then, FTP command
put is used to copy file my_db2.f from the local file system to folder
/sys/asm/DATA/dbs.
Database administrators can copy Oracle Automatic Storage Management (Oracle
ASM) files from one database server to another or between the database and a local file
system. Example 28–2 shows copying between two databases. For this, the proxy FTP
client method can be used, if available. The proxy method provides a direct
connection to two different remote FTP servers.
Example 28–2 copies an Oracle ASM file from one database to another. Terms with the
suffix 1 correspond to database server1. Terms with the suffix 2 correspond to

Accessing the Repository using Protocols

28-11

Using FTP and Oracle XML DB Protocol Server

database server2. Note that, depending on your FTP client, the passwords you type
might be echoed on your screen. Take the necessary precautions so that others do not
see these passwords.
Example 28–2
Method
1
2
3
4
5
6
7
8
9
10
11
12

Transferring Oracle ASM Files Between Databases with FTP proxy

ftp> open server1 port1
ftp> user username1
Password required for USERNAME1
Password: password-for-username1
ftp> cd /sys/asm/DATAFILE/MFG/DATAFILE
ftp> proxy open server2 port2
ftp> proxy user username2
Password required for USERNAME2
Password: password-for-username2
ftp> proxy cd /sys/asm/DATAFILE/MFG/DATAFILE
ftp> proxy put dbs2.f tmp1.f
ftp> proxy get dbs1.f tmp2.f

In Example 28–2:
■

Line 1 opens an FTP control connection to the Oracle XML DB FTP server,
server1.

■

Lines 2–4 log the database administrator onto server1 as USERNAME1.

■

Line 5 navigates to /sys/asm/DATAFILE/MFG/DATAFILE on server1.

■

Line 6 opens an FTP control connection to the second database server, server2.
At this point, the FTP command proxy ? could be issued to see the available FTP
commands on the secondary connection. (This is not shown.)

■

Lines 7–9 log the database administrator onto server2 as USERNAME2.

■

Line 10 navigates to /sys/asm/DATAFILE/MFG/DATAFILE on server2.

■

■

Line 11 copies Oracle ASM file dbs2.f from server2 to Oracle ASM file tmp1.f
on server1.
Line 12 copies Oracle ASM file dbs1.f from server1 to Oracle ASM file tmp2.f
on server2.

Using FTP on the Standard Port Instead of the Oracle XML DB Default Port
You can use the Oracle XML DB configuration file, /xdbconfig.xml, to configure
FTP to listen on any port. By default, FTP listens on a nonstandard, unprotected port.
To use FTP on the standard port, 21, your database administrator must do the
following:
1.

(UNIX only) Use this shell command to ensure that the owner and group of
executable file tnslsnr are root:
% chown root:root $ORACLE_HOME/bin/tnslsnr

2.

(UNIX only) Add the following entry to the listener file, listener.ora, where
hostname is your host name:
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP) (HOST = hostname) (PORT = 21))
(PROTOCOL_STACK = (PRESENTATION = FTP) (SESSION = RAW)))

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Using FTP and Oracle XML DB Protocol Server

3.

(UNIX only) Use shell command id to determine the user_id and group_id
that were used to install Oracle Database. oracle_installation_user is the
name of the user who installed the database.
% id oracle_installation_user
uid=user_id(oracle_installation_user) gid=group_id(dba)

4.

(UNIX only) Stop, then restart the listener, using the following shell commands,
where user_id and group_id are the UNIX user and group identifiers obtained
in step 3.
% lsnrctl stop
% tnslsnr LISTENER -user user_id -group group_id &

Use the ampersand (&), to execute the second command in the background. Do not
use lsnrctl start to start the listener.
5.

Use PL/SQL procedure DBMS_XDB.setftpport with SYS as SYSDBA to set
the FTP port number to 21 in the Oracle XML DB configuration file
/xdbconfig.xml.
SQL> exec DBMS_XDB.setFTPPort(21);

6.

Force the database to reregister with the listener, using this SQL statement:
SQL> ALTER SYSTEM REGISTER;

7.

Check that the listener is correctly configured, using this shell command:
% lsnrctl status

See Also:
■

■

Oracle Database Net Services Reference for information about listener
parameters and file listener.ora
Oracle Database Net Services Reference, section "Port Number
Limitations" for information about running on privileged ports

Using IPv6 IP Addresses with FTP
Starting with 11g Release 2 (11.2), Oracle Database supports the use of Internet
Protocol Version 6, IPv6 (in addition to Internet Protocol Version 4). Example 28–3
shows how to make an FTP connection with the IPv6 address
2001::0db8:ffff:ffff:ffff.
Example 28–3

FTP Connection Using IPv6

ftp> open 2001::0db8:ffff:ffff:ffff 1521
Connected to 2001::0db8:ffff:ffff:ffff.
220- xmlhost.example.com
Unauthorized use of this FTP server is prohibited and may be subject to civil and
criminal prosecution.
220- xmlhost.example.com FTP server (Oracle XML DB/Oracle Database) ready.
User (2001::0db8:ffff:ffff:ffff:(none)): username
331 pass required for USERNAME
Password: password-for-username
230 USERNAME logged in
ftp>

See Also:

Oracle Database Net Services Reference for information about

IPv6

Accessing the Repository using Protocols

28-13

Using HTTP(S) and Oracle XML DB Protocol Server

FTP Server Session Management
Oracle XML DB protocol server also provides session management for this protocol.
After a short wait for a new command, FTP returns to the protocol layer and the
shared server is freed up to serve other connections. The duration of this short wait is
configurable by changing parameter call-timeout in the Oracle XML DB
configuration file. For high traffic sites, call-timeout should be shorter, so that
more connections can be served. When new data arrives on the connection, the FTP
server is re-invoked with fresh data. So, the long running nature of FTP does not affect
the number of connections which can be made to the protocol server.
See Also: "Configuring Oracle XML DB using xdbconfig.xml" on
page 34-5 for information about configuring Oracle XML DB
parameters

Handling Error 421. Modifying the Default Timeout Value of an FTP Session
If you are frequently disconnected from the server and must reconnect and traverse
the entire directory before doing the next operation, you may need to modify the
default timeout value for FTP sessions. If the session is idle for more than this period,
it gets disconnected. You can increase the timeout value (default = 6000 centiseconds)
by modifying the configuration document as follows and then restart the database:
Example 28–4

Modifying the Default Timeout Value of an FTP Session

DECLARE
newconfig XMLType;
BEGIN
SELECT
updateXML(
DBMS_XDB.cfg_get(),
'/xdbconfig/sysconfig/protocolconfig/ftpconfig/session-timeout/text()',
123456789)
INTO newconfig
FROM DUAL;
DBMS_XDB.cfg_update(newconfig);
END;
/
COMMIT;

FTP Client Failure in Passive Mode
Do not use FTP in passive mode to connect remotely to a server that has HOSTNAME
configured in listener.ora as localhost or 127.0.0.1. If the HOSTNAME
specified in server file listener.ora is localhost or 127.0.0.1, then the server
is configured for local use only. If you try to connect remotely to the server using FTP in
passive mode, the FTP client fails. This is because the server passes IP address
127.0.0.1 (derived from HOSTNAME) to the client, which makes the client try to
connect to itself, not to the server.

Using HTTP(S) and Oracle XML DB Protocol Server
Oracle XML DB implements HyperText Transfer Protocol (HTTP), HTTP 1.1 as defined
in the RFC2616 specification.

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Using HTTP(S) and Oracle XML DB Protocol Server

Oracle XML DB Protocol Server: HTTP(S) Features
The Oracle XML DB HTTP(S) component in the Oracle XML DB protocol server
implements the RFC2616 specification with the exception of the following optional
features:
■

gzip and compress transfer encodings

■

byte-range headers

■

The TRACE method (used for proxy error debugging)

■

Cache-control directives (these require you to specify expiration dates for content,
and are not generally used)

■

TE, Trailer, Vary & Warning headers

■

Weak entity tags

■

Web common log format

■

Multi-homed Web server
See Also: RFC 2616: HTTP 1.1 Protocol
Specification—http://www.ietf.org/rfc/rfc2616.txt

HTTP(S) Features That Are Not Supported
Digest Authentication (RFC 2617) is not supported. Oracle XML DB supports Basic
Authentication, where a client sends the user name and password in clear text in the
Authorization header.

Supported HTTP(S) Client Methods
For access to the repository, Oracle XML DB supports the following HTTP(S) client
methods.
■

OPTIONS – get information about available communication options

■

GET – get document/data (including headers)

■

HEAD – get headers only, without document body

■

PUT – store data in resource

■

DELETE – delete resource

The semantics of these HTTP(S) methods is in accordance with WebDAV. Servlets and
Web services may support additional HTTP(S) methods, such as POST.
See Also: "Supported WebDAV Client Methods" on page 28-21 for
supported HTTP(S) client methods involving WebDAV

Using HTTP(S) on a Standard Port Instead of an Oracle XML DB Default Port
You can use the Oracle XML DB configuration file, /xdbconfig.xml, to configure
HTTP(S) to listen on any port. By default, HTTP(S) listens on a nonstandard,
unprotected port. To use HTTP or HTTPS on a standard port (80 for HTTP, 443 for
HTTPS), your database administrator must do the following:
1.

(UNIX only) Use this shell command to ensure that the owner and group of
executable file tnslsnr are root:
% chown root:root $ORACLE_HOME/bin/tnslsnr

Accessing the Repository using Protocols

28-15

Using HTTP(S) and Oracle XML DB Protocol Server

2.

(UNIX only) Add the following entry to the listener file, listener.ora, where
hostname is your host name, and port_number is 80 for HTTP or 443 for
HTTPS:
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP) (HOST = hostname) (PORT = port_number))
(PROTOCOL_STACK = (PRESENTATION = HTTP) (SESSION = RAW)))

3.

(UNIX only) Use shell command id to determine the user_id and group_id
that were used to install Oracle Database. oracle_installation_user is the
name of the user who installed the database.
% id oracle_installation_user
uid=user_id(oracle_installation_user) gid=group_id(dba)

4.

(UNIX only) Stop, then restart the listener, using the following shell commands,
where user_id and group_id are the UNIX user and group identifiers obtained
in step 3.
% lsnrctl stop
% tnslsnr LISTENER -user user_id -group group_id &

Use the ampersand (&), to execute the second command in the background. Do not
use lsnrctl start to start the listener.
5.

Use PL/SQL procedure DBMS_XDB.sethtpport with SYS as SYSDBA to set
the HTTP(S) port number to port_number in the Oracle XML DB configuration
file /xdbconfig.xml, where port_number is 80 for HTTP or 443 for HTTPS:
SQL> exec DBMS_XDB.setHTTPPort(port_number);

6.

Force the database to reregister with the listener, using this SQL statement:
SQL> ALTER SYSTEM REGISTER;

7.

Check that the listener is correctly configured:
% lsnrctl status

See Also:
■

■

Oracle Database Net Services Reference for information about listener
parameters and file listener.ora
Oracle Database Net Services Reference, section "Port Number
Limitations" for information about running on privileged ports

Using IPv6 IP Addresses with HTTP(S)
Starting with 11g Release 2 (11.2), Oracle Database supports the use of Internet
Protocol Version 6, IPv6 (in addition to Internet Protocol Version 4). IPv6 addresses in
URLs are enclosed in brackets ([]). Here is an example:
http://[2001::0db8:ffff:ffff:ffff]:8080/

See Also: Oracle Database Net Services Reference for information about
IPv6

HTTPS: Support for Secure HTTP
If properly configured, you can access Oracle XML DB Repository in a secure fashion,
using HTTPS. See "Configuring Secure HTTP (HTTPS)" on page 28-6 for configuration
information.

28-16 Oracle XML DB Developer's Guide

Using HTTP(S) and Oracle XML DB Protocol Server

If Oracle Database is installed on Microsoft Windows XP with
Service Pack 2 (SP2), then you must use HTTPS for WebDAV access to
Oracle XML DB Repository, or else you must make appropriate
modifications to the Windows XP Registry. For information about the
latter, see
http://www.microsoft.com/technet/prodtechnol/winxppr
o/maintain/sp2netwk.mspx#XSLTsection129121120120

Note:

Controlling URL Expiration Time
Optional configuration parameter expire specifies an HTTP Expires header. This
header acts as a directive to the HTTP client, to specify the expiration date and time for
a URL.
If cached, the document targeted by a URL can be fetched from the client cache rather
than from the server, until this expiration time has passed. After that time, the cache
copy is out-of-date and a new copy must be obtained from the source (server).
The Oracle XML DB syntax for the Expires header, which is used in the expire
configuration element, is a subset of the so-called alternate syntax defined for the
ExpiresDefault directive of the Apache module mod_expires. See
http://httpd.apache.org/docs/2.0/mod/mod_expires.html#AltSyn for
that syntax.
These are the Oracle XML DB restrictions to the ExpiresDefault syntax:
■

■

■

You cannot use access as the . Only now and modification are
allowed.
The  values must appear in order of decreasing time period. For example,
year must appear before, not after, month, since a year is a longer time period
than a month.
You can use at most one occurrence of each of the different  values. For
example, you cannot have multiple year entries or multiple day entries.

Anonymous Access to Oracle XML DB Repository using HTTP
Optional configuration parameter allow-repository-anonymous-access
controls whether or not anonymous HTTP access to Oracle XML DB Repository data is
allowed using an unlocked ANONYMOUS user account. The default value is false,
meaning that unauthenticated access to repository data is blocked. To allow anonymous
HTTP access to the repository, you must set this parameter to true, and unlock the
ANONYMOUS user account.
Caution: There is an inherent security risk associated with allowing
anonymous access to the repository.

Parameter allow-repository-anonymous-access does not control anonymous
access to the repository using servlets. Each servlet has its own security-role-ref
parameter value to control its access.

Accessing the Repository using Protocols

28-17

Using HTTP(S) and Oracle XML DB Protocol Server

See Also:
■

■

■

Table 28–3 on page 28-5 for information about parameter
allow-repository-anonymous-access
"Configuring Oracle XML DB using xdbconfig.xml" on page 34-5
for information about configuring Oracle XML DB parameters
"Configuring Oracle XML DB Servlets" on page 32-3 for
information about parameter security-role-ref

Using Java Servlets with HTTP(S)
Oracle XML DB supports Java servlets. To use a Java servlet, it must be registered with
a unique name in the Oracle XML DB configuration file, along with parameters to
customize its action. It should be compiled, and loaded into the database. Finally, the
servlet name must be associated with a pattern, which can be an extension such as
*.jsp or a path name such as /a/b/c or /sys/*, as described in Java servlet
application program interface (API) version 2.2.
While processing an HTTP(S) request, the path name for the request is matched with
the registered patterns. If there is a match, then the protocol server invokes the
corresponding servlet with the appropriate initialization parameters. For Java servlets,
the existing Java Virtual Machine (JVM) infrastructure is used. This starts the JVM if
need be, which in turn invokes a Java method to initialize the servlet, create response,
and request objects, pass these on to the servlet, and run it.
See Also: Chapter 32, "Writing Oracle XML DB Applications in
Java"

Embedded PL/SQL Gateway
You can use the PL/SQL gateway to implement a Web application entirely in PL/SQL.
There are two implementations of the PL/SQL gateway:
■

■

mod_plsql – a plug-in of Oracle HTTP Server that lets you invoke PL/SQL stored
procedures using HTTP(S). Oracle HTTP Server is a component of both Oracle
Application Server and Oracle Database. Do not confuse Oracle HTTP Server with
the HTTP component of the Oracle XML DB protocol server.
the embedded PL/SQL gateway – a gateway implementation that runs in the Oracle
XML DB HTTP listener.

With the PL/SQL gateway (either implementation), a Web browser sends an HTTP(S)
request in the form of a URL that identifies a stored procedure and provides it with
parameter values. The gateway translates the URL, calls the stored procedure with the
parameter values, and returns output (typically HTML) to the Web-browser client.
Using the embedded PL/SQL gateway simplifies installation, configuration, and
administration of PL/SQL based Web applications. The embedded gateway uses the
Oracle XML DB protocol server, not Oracle HTTP Server. Its configuration is defined
by the Oracle XML DB configuration file, /xdbconfig.xml. However, the
recommended way to configure the embedded gateway is to use the procedures in
PL/SQL package DBMS_EPG, not to edit file /xdbconfig.xml.

28-18 Oracle XML DB Developer's Guide

Using HTTP(S) and Oracle XML DB Protocol Server

See Also:
■

■

■

■

Oracle Database Advanced Application Developer's Guide for
information on using and configuring the embedded PL/SQL
gateway
Chapter 34, "Administering Oracle XML DB" for information
on the configuration definition of the embedded gateway in
/xdbconfig.xml
Oracle Fusion Middleware Administrator's Guide for Oracle HTTP
Server for conceptual information about using the PL/SQL
gateway
Oracle HTTP Server mod_plsql User's Guide for information
about mod_plsql

Sending Multibyte Data From a Client
When a client sends multibyte data in a URL, RFC 2718 specifies that the client should
send the URL using the %HH format, where HH is the hexadecimal notation of the byte
value in UTF-8 encoding. The following are URL examples that can be sent to Oracle
XML DB in an HTTP(S) or WebDAV context:
http://urltest/xyz%E3%81%82%E3%82%A2
http://%E3%81%82%E3%82%A2
http://%E3%81%82%E3%82%A2/abc%E3%81%86%E3%83%8F.xml

Oracle XML DB processes the requested URL, any URLs within an IF header, any
URLs within the DESTINATION header, and any URLs in the REFERRED header that
contains multibyte data.
The default-url-charset configuration parameter can be used to accept requests
from some clients that use other, nonconforming, forms of URL, with characters that
are not ASCII. If a request with such characters fails, try setting this value to the native
character set of the client environment. The character set used in such URL fields must
be specified with an IANA charset name.
default-url-charset controls the encoding for nonconforming URLs. It is not
required to be set unless a nonconforming client that does not send the
Content-Type charset is used.
See Also:
■

■

RFC 2616: HTTP 1.1 Protocol Specification,
http://www.ietf.org/rfc/rfc2616.txt
"Configuring Oracle XML DB using xdbconfig.xml" on
page 34-5 for information about configuring Oracle XML DB
parameters

Characters That Are Not ASCII in URLs
Characters that are not ASCII that appear in URLs passed to an HTTP server should be
converted to UTF-8 and escaped in the %HH format, where HH is the hexadecimal
notation of the byte value. For flexibility, the Oracle XML DB protocol server interprets
the incoming URLs by testing whether it is encoded in one of the following character
sets in the order presented here:
■

UTF-8

■

Charset parameter of the Content-Type field of the request, if specified

Accessing the Repository using Protocols

28-19

Using WebDAV and Oracle XML DB

■

■

Character set, if specified, in the default-url-charset configuration
parameter
Character set of the database
See Also: "Configuring Oracle XML DB using xdbconfig.xml" on
page 34-5 for information about configuring Oracle XML DB
parameters

Controlling Character Sets for HTTP(S)
The following sections describe how character sets are controlled for data transferred
using HTTP(S).
Request Character Set The character set of the HTTP(S) request body is determined with
the following algorithm:
■

■

The Content-Type header is evaluated. If the Content-Type header specifies a
charset value, the specified charset is used.
The MIME type of the document is evaluated as follows:
■

If the MIME type is "*/xml", the character set is determined as follows:
- If a BOM is present, then UTF-16 is used.
- If an encoding declaration is present, the specified encoding is used.
- If neither a BOM nor an encoding declaration is present, UTF-8 is used.

■
■

If the MIME type is text, ISO8859-1 is used.
If the MIME type is neither "*/xml" nor text, the database character set is
used.

There is a difference between HTTP(S) and SQL or FTP. For text documents, the
default is ISO8859-1, as specified by the IETF.org RFC 2616: HTTP 1.1 Protocol
Specification.
Response Character Set
The response generated by Oracle XML DB HTTP Server is in the character set
specified in the Accept-Charset field of the request. Accept-Charset can have a
list of character sets. Based on the q-value, Oracle XML DB chooses one that does not
require conversion. This might not necessarily be the charset with the highest q-value.
If Oracle XML DB cannot find one, then the conversion is based on the highest q-value.

Using WebDAV and Oracle XML DB
Web Distributed Authoring and Versioning (WebDAV) is an IETF standard protocol
used to provide users with a file-system interface to Oracle XML Repository over the
Internet. The most popular way of accessing a WebDAV server folder is through
WebFolders using Microsoft Windows.
WebDAV is an extension to the HTTP 1.1 protocol that lets an HTTP server act as a file
server. It lets clients perform remote Web content authoring through a coherent set of
methods, headers, request body formats and response body formats. For example, a
DAV-enabled editor can interact with an HTTP/WebDAV server as if it were a file
system. WebDAV provides operations to store and retrieve resources, create and list
contents of resource collections, lock resources for concurrent access in a coordinated
manner, and to set and retrieve resource properties.

28-20 Oracle XML DB Developer's Guide

Using WebDAV and Oracle XML DB

Oracle XML DB WebDAV Features
Oracle XML DB supports the following WebDAV features:
■

Foldering, specified by RFC2518

■

Access Control

WebDAV is a set of extensions to the HTTP(S) protocol that allow you to edit or
manage your files on remote Web servers. WebDAV can also be used, for example, to:
■

Share documents over the Internet

■

Edit content over the Internet
See Also: RFC 2518: WebDAV Protocol Specification,
http://www.ietf.org/rfc/rfc2518.txt

WebDAV Features That Are Not Supported
Oracle XML DB supports the contents of RFC2518, with the following exceptions:
■

■

Lock-NULL resources create zero-length resources in the file system, and cannot be
converted to folders.
Methods COPY, MOVE and DELETE comply with section 2 of the Internet Draft
titled 'Binding Extensions to WebDAV'.

■

Depth-infinity locks

■

Only Basic Authentication is supported.

Supported WebDAV Client Methods
For access to the repository, Oracle XML DB supports the following
HTTP(S)/WebDAV client methods.
■

PROPFIND (WebDAV-specific) – get properties for a resource

■

PROPPATCH (WebDAV-specific) – set or remove resource properties

■

LOCK (WebDAV-specific) – lock a resource (create or refresh a lock)

■

UNLOCK (WebDAV-specific) – unlock a resource (remove a lock)

■

COPY (WebDAV-specific) – copy a resource

■

MOVE (WebDAV-specific) – move a resource

■

MKCOL (WebDAV-specific) – create a folder resource (collection)
See Also:
■

■

■

"Supported HTTP(S) Client Methods" on page 28-15 for additional
supported HTTP(S) client methods
"Privileges" on page 27-5 for information about WebDAV
privileges
"Adding Metadata using WebDAV PROPPATCH" on page 29-8

Using WebDAV with Microsoft Windows XP SP2
If Oracle Database is installed on Microsoft Windows XP with Service Pack 2 (SP2), then
you must use a secure connection (HTTPS) for WebDAV access to Oracle XML DB
Repository, or else you must make appropriate modifications to the Windows XP
Registry.
Accessing the Repository using Protocols

28-21

Using WebDAV and Oracle XML DB

See Also:
■

■

http://www.microsoft.com/technet/prodtechnol/winxpp
ro/maintain/sp2netwk.mspx#XSLTsection129121120120
for information about making necessary modifications to the
Windows XP registry
"Configuring Secure HTTP (HTTPS)" on page 28-6

Creating a WebFolder in Microsoft Windows using Oracle XML DB and WebDAV
To create a WebFolder in Windows 2000, follow these steps:
1.

Start > My Network Places.

2.

Double-click Add Network Place.

3.

Click Next.

4.

Type the location of the folder, for example:
http://Oracle_server_name:HTTP_port_number

See Figure 28–2.
5.

Click Next.

6.

Enter any name to identify this WebFolder

7.

Click Finish.

You can access Oracle XML DB Repository the same way that you access any Windows
folder.
Figure 28–2 Creating a WebFolder in Microsoft Windows

28-22 Oracle XML DB Developer's Guide

29
User-Defined Repository Metadata
This chapter describes how to create and use XML metadata, which you associate with
XML data and store in Oracle XML DB Repository.
This chapter contains these topics:
■

Overview of Metadata and XML

■

XML Schemas to Define Resource Metadata

■

Adding, Updating, and Deleting Resource Metadata

■

Querying XML Schema-Based Resource Metadata

■

XML Image Metadata from Binary Image Metadata

■

Adding Non-Schema-Based Resource Metadata

■

PL/SQL Procedures Affecting Resource Metadata

Overview of Metadata and XML
Data that you use is often associated with additional information that is not part of the
content. To process it in different ways, you can use such metadata to group or classify
data. For example, you might have a collection of digital photographs, and you might
associate metadata with each picture, such as information about the photographic
characteristics (color composition, focal length) or context (location, kind of subject:
landscape, people).
An Oracle XML DB repository resource is an XML document that contains both
metadata and data. The data is the contents of element Contents. All other elements
in the resource contain metadata. The data of a resource can be XML, but it need not
be.
You can associate resources in the Oracle XML DB repository with metadata that you
define. In addition to such user-defined metadata, each repository resource also has
associated metadata that Oracle XML DB creates automatically and uses
(transparently) to manage the resource. Such system-defined metadata includes
properties such as the owner and creation date of each resource.
Except for system-defined metadata, you decide which resource information should be
treated as data and which should be treated as metadata. For a photo resource,
supplemental information about the photo is normally not considered to be part of the
photo data, which is a binary image. For text, however, you sometimes have a choice
of whether to include particular information in the resource contents (data) or keep it
separate and associate it with the contents as metadata—that choice is often
influenced by the applications that use or produce the data.

User-Defined Repository Metadata

29-1

Overview of Metadata and XML

Kinds of Metadata – Uses of the Term
In addition to resource metadata (system-defined and user-defined), the term
"metadata" is sometimes used to refer to the following:
■
■

An XML schema is metadata that describes a class of XML documents.
An XML tag (element or attribute name) is metadata that is used to label and
organize the element content or attribute value.

You can associate metadata with an XML document that is the content of a repository
resource in any of these ways:
■

■

■

You can add additional XML elements containing the metadata information to the
resource contents. For example, you could wrap digital image data in an XML
document that also includes elements describing the photo. In this case, the data
and its metadata are associated by being in the contents of the same resource. It is
up to applications to separate the two and relate them correctly.
You can add metadata information for a particular resource to the repository as the
contents of a separate resource. In this case, it is up to applications to treat this
resource as metadata and associate it with the data.
You can add metadata information for a resource as repository resource metadata. In
this case, Oracle XML DB recognizes the metadata as such. Applications can
discover this metadata by querying the repository for it. They need not be informed
separately of its existence and its association with the data.
See Also:

"Oracle XML DB Repository Resources" on page 21-5

User-Defined Resource Metadata
Of these different ways of considering metadata, this chapter is about only the last of
those just listed: user-defined resource metadata. Such metadata is itself represented as
XML: it is XML data that is associated with other XML data, describing it or providing
supplementary, related information.
User-defined metadata for resources can be either XML schema-based or not:
■

■

Resource metadata that is schema-based is stored in separate (out-of-line) tables.
These are related to the resource table by the resource OID, which is stored in the
hidden object column RESID of the metadata tables.
Resource metadata that is not schema-based is stored in a CLOB column in the
resource table.

You can take advantage of schema-based metadata, in particular, to perform efficient
queries and DML operations on resources. In this chapter, you learn how to perform
the following tasks involving schema-based resource metadata:
■

Create and register an XML schema that defines the metadata for a particular kind
of resource.

■

Add metadata to a repository resource, and update (modify) such metadata.

■

Query resource metadata to find associated content.

■

Delete specific metadata associated with a resource and purge all metadata
associated with a resource.

In addition, you learn how to add non-schema-based metadata to a resource.
You can generally use user-defined resource metadata just as you would use resource
data. In particular, versioning and access control management apply.

29-2 Oracle XML DB Developer's Guide

XML Schemas to Define Resource Metadata

Typical uses of resource metadata include workflow applications, enforcing user rights
management, tracking resource ownership, and controlling resource validity dates.

Scenario: Metadata for a Photo Collection
To illustrate the use of schema-based resource metadata, this chapter uses metadata
associated with photographic image files that are stored in repository resources. You
can create any number of different kinds of metadata to be associated with the same
resource. For image files, examples create metadata for information about both 1) the
technical aspects of a photo and 2) the photo subject or the uses to which a photo
might be put. These two kinds of associated metadata are used to query photo
resources.

XML Schemas to Define Resource Metadata
This section first defines the metadata to associate with each photo resource using
XML Schema. An XML schema is created and registered for each kind (technique,
category) of metadata.
The XML schema in Example 29–1 defines metadata used to describe the technical
aspects of a photo image file. It uses PL/SQL procedure DBMS_
XMLSCHEMA.registerSchema to register the XML schema. To identify this schema
as defining repository resource metadata, it uses ENABLE_HIERARCHY_RESMETADATA
as the value for parameter enableHierarchy. Resource contents (data) are defined
by using value ENABLE_HIERARCHY_CONTENTS (the default value), instead.
The properties defined in Example 29–1 are the image height, width, color depth, title,
and brief description.
Example 29–1

Register an XML Schema for Technical Photo Information

BEGIN
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL
=> 'imagetechnique.xsd',
SCHEMADOC
=> '











',
enableHierarchy => DBMS_XMLSCHEMA.ENABLE_HIERARCHY_RESMETADATA);
END;
/

The XML schema in Example 29–2 defines metadata used to categorize a photo image
file: to describe its content or possible uses. This simple example defines a single,
general property for classification, named Category.

User-Defined Repository Metadata

29-3

Adding, Updating, and Deleting Resource Metadata

Example 29–2

Register an XML Schema for Photo Categorization
BEGIN
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL
=> 'imagecategories.xsd',
SCHEMADOC
=> '












',
enableHierarchy => DBMS_XMLSCHEMA.ENABLE_HIERARCHY_RESMETADATA);
END;
/

Notice that there is nothing in the XML schema definitions of metadata that restrict
that information to being associated with any particular kind of data. You are free to
associate any type of metadata with any type of resource. And multiple types of
metadata can be associated with the same resource.
Notice, too, that the XML schema does not, by itself, define its associated data as being
metadata—it is the schema registration that makes this characterization, through
enableHierarchy value ENABLE_HIERARCHY_RESMETADATA. If the same schema
were registered instead with enableHierarchy value ENABLE_HIERARCHY_
CONTENTS (the default value), then it would define not metadata for resources, but
resource contents with the same information. The same XML schema cannot be
registered more than once under the same name.

XML schema-based user-defined metadata is stored as a CLOB,
by default. You can store it as binary XML, instead, by setting the
OPTIONS parameter for XML schema registration to REGISTER_
BINARYXML.

Note:

Adding, Updating, and Deleting Resource Metadata
You can add, update, and delete user-defined resource metadata in the following
ways:
■

Use PL/SQL procedures in package DBMS_XDB:
–

appendResourceMetadata – add metadata to a resource

–

updateResourceMetadata – modify resource metadata

–

deleteResourceMetadata – delete specific metadata from a resource

29-4 Oracle XML DB Developer's Guide

Adding, Updating, and Deleting Resource Metadata

–
■

■

purgeResourceMetadata – delete all metadata from a resource

Use SQL DML statements INSERT, UPDATE, and DELETE to update the resource
directly
Use WebDAV protocol method PROPPATCH

You use SQL DM statements and WebDAV method PROPPATCH to update or delete
metadata in the same way as you add metadata. If you supply a complete Resource
element for one of these operations, then keep in mind that each resource metadata
property must be a child (not just a descendant) of element Resource—if you want
multiple metadata elements of the same kind, you must collect them as children of a
single parent metadata element. The order among such top-level user-defined resource
metadata properties is unimportant and is not necessarily maintained by Oracle
XML DB.
The separate PL/SQL procedures in package DBMS_XDB are similar in their use. Each
can be used with either XML schema-based or non-schema-based metadata. Some
forms (signatures) of some of the procedures apply only to schema-based metadata.
Procedures appendResourceMetadata and deleteResourceMetadata are
illustrated here with examples.
See Also: Oracle Database PL/SQL Packages and Types Reference for
information about the procedures in PL/SQL package DBMS_XDB

Adding Metadata using APPENDRESOURCEMETADATA
You can use procedure DBMS_XDB.appendResourceMetadata to add user-defined
metadata to resources.
Example 29–3 creates a photo resource and adds XML schema-based metadata of type
ImgTechMetadata to it, recording the technical information about the photo.
Example 29–3

Add Metadata to a Resource – Technical Photo Information

DECLARE
returnbool BOOLEAN;
BEGIN
returnbool := DBMS_XDB.createResource(
'/public/horse_with_pig.jpg',
bfilename('MYDIR', 'horse_with_pig.jpg'));
DBMS_XDB.appendResourceMetadata(
'/public/horse_with_pig.jpg',
XMLType('
1024
768
24

Picture of a pig riding a horse on the beach,
taken outside hotel window.
'));
END;
/

Example 29–4 adds metadata of type ImgTechMetadata to the same resource as
Example 29–3, placing the photo in several user-defined content categories.

User-Defined Repository Metadata

29-5

Adding, Updating, and Deleting Resource Metadata

Example 29–4

Add Metadata to a Resource – Photo Content Categories

BEGIN
DBMS_XDB.appendResourceMetadata(
'/public/horse_with_pig.jpg',
XMLType('

Vacation
Animals
Humor
2005

'));
END;
/
PL/SQL procedure successfully completed.
SELECT * FROM imgcatmetadatatable;
SYS_NC_ROWINFO$
-------------------------------------------------------------------------------

Vacation
Animals
Humor
2005


1 row selected.

Deleting Metadata using DELETERESOURCEMETADATA
You can use procedure DBMS_XDB.deleteResourceMetadata to delete specific
metadata associated with a resource. To delete all of the metadata associated with a
resource, you can use procedure DBMS_XDB.purgeResourceMetadata.
Example 29–5 deletes the category metadata that was added to the photo resource in
Example 29–4. By default, both the resource link (REF) to the metadata and the
metadata table identified by that link are deleted. An optional parameter can be used
to specify that only the link is to be deleted. The metadata table is then left as is but
becomes unrelated to the resource. In this example, the default behavior is used.
Example 29–5

Delete Specific Metadata from a Resource

BEGIN
DBMS_XDB.deleteResourceMetadata('/public/horse_with_pig.jpg',
'cnamespace',
'ImgCatMetadata');
END;
/
PL/SQL procedure successfully completed.
SELECT * FROM imgcatmetadatatable;
29-6 Oracle XML DB Developer's Guide

Adding, Updating, and Deleting Resource Metadata

no rows selected

Adding Metadata using SQL DML
An alternative to using procedure DBMS_XDB.appendResourceMetadata to add,
update, or delete resource metadata is to update the RESOURCE_VIEW directly using
DML statements INSERT and UPDATE.
Adding resource metadata in this way is illustrated by Example 29–6. It shows how to
accomplish the same thing as Example 29–3 by inserting the metadata directly into
RESOURCE_VIEW using SQL statement UPDATE. Other SQL DML statements may be
used similarly.
Example 29–6

Adding Metadata to a Resource using DML with RESOURCE_VIEW

UPDATE RESOURCE_VIEW
SET RES =
insertChildXML(
RES,
'/r:Resource',
'c:ImgCatMetadata',
XMLType('

Vacation
Animals
Humor
2005

'),
'xmlns:r="http://xmlns.oracle.com/xdb/XDBResource.xsd"
xmlns:c="cnamespace"')
WHERE equals_path(RES, '/public/horse_with_pig.jpg') = 1;
/
SELECT * FROM imgcatmetadatatable;
SYS_NC_ROWINFO$
-------------------------------------------------------------------------------

Vacation
Animals
Humor
2005


1 row selected.

The following query extracts the inserted metadata using RESOURCE_VIEW, rather
than directly using metadata table imgcatmetadatatable. (The result is shown here
pretty-printed, for clarity.)
SELECT XMLQuery('declare namespace r
= "http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)

User-Defined Repository Metadata

29-7

Adding, Updating, and Deleting Resource Metadata

declare namespace c
= "cnamespace"; (: :)
/r:Resource/c:ImgCatMetadata'
PASSING RES RETURNING CONTENT)
FROM RESOURCE_VIEW
WHERE equals_path(RES, '/public/horse_with_pig.jpg') = 1;
XMLQUERY('DECLARENAMESPACER="HTTP://XMLNS.ORACLE.COM/XDB/XDBRESOURCE.XSD";(::)DE
-------------------------------------------------------------------------------

Vacation
Animals
Humor
2005


1 row selected.

Adding Metadata using WebDAV PROPPATCH
Another alternative to using procedure DBMS_XDB.appendResourceMetadata to
add resource metadata is to use WebDAV method PROPPATCH. This is illustrated in
Example 29–7. You can update and delete metadata similarly.
Example 29–7 shows how to accomplish the same thing as Example 29–4 by inserting
the metadata using WebDAV method PROPPATCH. Using appropriate tools, your
application creates such a PROPPATCH WebDAV request and sends it to the WebDAV
server for processing.
To update user-defined metadata, you proceed in the same way. To delete user-defined
metadata, the WebDAV request is similar, but it has D:remove in place of D:set.
Example 29–7

Adding Metadata using WebDAV PROPPATCH

PROPPATCH /public/horse_with_pig.jpg HTTP/1.1
Host: www.example.com
Content-Type: text/xml; charset="utf-8"
Content-Length: 609
Authorization: Basic dGRhZHhkYl9tZXRhOnRkYWR4ZGJfbWV0YQ==
Connection: close






Vacation
Animals
Humor
2005



29-8 Oracle XML DB Developer's Guide

Querying XML Schema-Based Resource Metadata





Querying XML Schema-Based Resource Metadata
When you register an XML schema using the enableHierarchy value ENABLE_
HIERARCHY_RESMETADATA, an additional column, RESID, is added automatically to
the XMLType tables used to store the metadata. This column stores the object identifier
(OID) of the resource associated with the metadata. You can use column RESID when
querying metadata, to join the metadata with the associated data.
You can query metadata in these ways:
■

Query RESOURCE_VIEW for the metadata. For example:
SELECT count(*) FROM RESOURCE_VIEW
WHERE
XMLExists(
'declare namespace r
= "http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
declare namespace c
= "cnamespace"; (: :)
/r:Resource/c:ImgCatMetadata/Categories/Category[text()="Vacation"]'
PASSING RES);
COUNT(*)
---------1
1 row selected.

■

Query the XML schema-based table for the user-defined metadata directly, and
join this metadata back to the resource table, identifying which resource to select.
Use column RESID of the metadata table to do this. For example:
SELECT COUNT(*) FROM RESOURCE_VIEW rs, imgcatmetadatatable ct
WHERE
XMLExists(
'declare namespace r
= "http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
declare namespace c
= "cnamespace"; (: :)
/r:Resource/c:ImgCatMetadata/Categories/Category'
PASSING RES)
AND rs.RESID = ct.RESID;
COUNT(*)
---------1
1 row selected.

Oracle recommends querying for user-defined metadata directly, for performance
reasons. Direct queries of the RESOURCE_VIEW alone cannot be optimized using XPath
rewrite, because there is no way to determine whether or not target elements like
Category are stored in the CLOB value or in an out-of-line table.
To improve performance further, create an index on each metadata column you intend
to query.

User-Defined Repository Metadata

29-9

XML Image Metadata from Binary Image Metadata

Example 29–8 queries both kinds of photo resource metadata, retrieving the paths to
the resources that are categorized as vacation photos and have the title "Pig Riding
Horse".
Example 29–8

Query XML Schema-Based Resource Metadata

SELECT ANY_PATH
FROM RESOURCE_VIEW rs, imgcatmetadatatable ct, imgtechmetadatatable tt
WHERE XMLExists(
'declare namespace r
= "http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
declare namespace c
= "cnamespace"; (: :)
/r:Resource/c:ImgCatMetadata/Categories/Category[text()="Vacation"]'
PASSING RES)
AND XMLExists(
'declare namespace r
= "http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
declare namespace i
= "inamespace"; (: :)
/r:Resource/i:ImgTechMetadata/Title[text()="Pig Riding Horse"]'
PASSING RES)
AND rs.RESID = ct.RESID
AND rs.RESID = tt.RESID;
ANY_PATH
-------------------------/public/horse_with_pig.jpg
1 row selected.

XML Image Metadata from Binary Image Metadata
Previous sections of this chapter use a simple user-defined XML schema that defines
technical image metadata, imagetechnique.xsd, to illustrate ways of adding and
changing repository resource metadata. That simple XML schema is not intended to be
realistic with respect to technical photographic image information.
However, most digital cameras include image metadata as part of the binary image
files they produce, and Oracle interMedia, which is part of Oracle Database, provides
tools for extracting and converting this binary metadata to XML. Oracle interMedia
XML schemas are automatically registered with Oracle XML DB Repository to convert
binary image metadata of the followings kinds to XML data:
■
■

■

EXIF – Exchangeable Image File Format
IPTC-NAA IIM – International Press Telecommunications Council-Newspaper
Association of America Information Interchange Model
XMP – Extensible Metadata Platform

EXIF is the metadata standard for digital still cameras. EXIF metadata is stored in TIFF
and JPEG image files. IPTC and XMP metadata is commonly embedded in image files
by desktop image-processing software.

29-10 Oracle XML DB Developer's Guide

Adding Non-Schema-Based Resource Metadata

See Also:
■

■

Oracle Multimedia User's Guide for information about working
with digital image metadata, including examples of extracting
binary image metadata and converting it to XML
Oracle Multimedia Reference for information about the XML
schemas supported by Oracle interMedia for use with image
metadata

Adding Non-Schema-Based Resource Metadata
You store user-defined resource metadata that is not schema-based as a CLOB instance
under the Resource element of the associated resource. The default XML schema for
a resource has a top-level element any (declared with maxOccurs= "unbounded"),
which admits any valid XML data as part of the resource document. This metadata is
stored in a CLOB column of the resource table.
The following skeleton shows the structure and position of non-schema-based
resource metadata:
DESELBY
... 


value1
value2



You can set and access non-schema-based resource metadata belonging to namespaces
other than XDBResource.xsd by using any of the means described previously for
accessing XML schema-based resource metadata.
Example 29–9 illustrates this for the case of SQL DML operations, adding user-defined
metadata directly to the  document. It shows how to add
non-schema-based metadata to a resource using SQL DML.
Example 29–9

Add Non-Schema-Based Metadata to a Resource

DECLARE
res BOOLEAN;
BEGIN
res := DBMS_XDB.createResource('/public/NurseryRhyme.txt',
bfilename('MYDIR',
'tdadxdb-xdb_repos_meta-011.txt'),
nls_charset_id('AL32UTF8'));
UPDATE RESOURCE_VIEW
SET RES = insertChildXML(RES,
'/r:Resource',
'n:NurseryMetadata',
XMLType('
Mother Goose
'),
'xmlns:r="http://xmlns.oracle.com/xdb/XDBResource.xsd"

User-Defined Repository Metadata 29-11

PL/SQL Procedures Affecting Resource Metadata

xmlns:n="nurserynamespace"')
WHERE equals_path(RES, '/public/NurseryRhyme.txt') = 1;
END;
/
PL/SQL procedure successfully completed.

SELECT XMLSerialize(DOCUMENT rs.RES AS CLOB) FROM RESOURCE_VIEW rs
WHERE equals_path(RES, '/public/NurseryRhyme.txt') = 1;
XMLSERIALIZE(DOCUMENTRS.RESASCLOB)
-------------------------------------------------------------------------------
1 row selected.

PL/SQL Procedures Affecting Resource Metadata
The following PL/SQL procedures perform resource metadata operations:

29-12 Oracle XML DB Developer's Guide

PL/SQL Procedures Affecting Resource Metadata

■

■

■

■

■
■

■

■

DBMS_XMLSCHEMA.registerSchema – Register an XML schema. Parameter
ENABLEHIERARCHY affects resource metadata.
DBMS_XDBZ.enable_hierarchy – Enable repository support for an XMLType
table or view. Use parameter HIERARCHY_TYPE with a value of DBMS_
XDBZ.ENABLE_HIERARCHY_RESMETADATA to enable resource metadata. This
adds column RESID to track the resource associated with the metadata.
DBMS_XDBZ.disable_hierarchy – Disable all repository support for an
XMLType table or view.
DBMS_XDBZ.is_hierarchy_enabled – Tests, using parameter HIERARCHY_
TYPE, whether the specified type of hierarchy is currently enabled for the specified
XMLType table or view. Value DBMS_XDBZ.IS_ENABLED_RESMETADATA for
HIERARCHY_TYPE tests whether resource metadata is enabled.
DBMS_XDB.appendResourceMetadata – Add metadata to a resource.
DBMS_XDB.deleteResourceMetadata – Delete specified metadata from a
resource.
DBMS_XDB.purgeResourceMetadata – Delete all user-defined metadata from a
resource. For schema-based resources, optional parameter DELETE_OPTION can
be used to specify whether or not to delete the metadata information, in addition
to unlinking it.
DBMS_XDB.updateResourceMetadata – Update the metadata for a resource.
See Also: Oracle Database PL/SQL Packages and Types Reference for
detailed information about these PL/SQL procedures

User-Defined Repository Metadata 29-13

PL/SQL Procedures Affecting Resource Metadata

29-14 Oracle XML DB Developer's Guide

30
Oracle XML DB Repository Events
This chapter describes repository events and how to use them. It contains these topics:
■

Overview of Repository Events

■

Possible Repository Events

■

Repository Operations and Events

■

Repository Event Handler Considerations

■

Configuring Repository Events

Overview of Repository Events
You can use Oracle XML DB Repository to store and access data of any kind in the
form of repository resources: files and folders. Repository resource operations include
creating, deleting, locking, unlocking, rendering, linking, unlinking, placing under
version control, checking in, checking out, unchecking out (reverting a checked out
version), opening, and updating. You can access data in the repository from any
application. Sometimes your application needs to perform certain actions whenever a
particular repository operation occurs. For example, you might want to perform some
move-to-wastebasket or other backup action whenever a resource is deleted.

Repository Events: Use Cases
The following are examples of cases where repository events can be used:
■

■

Wastebasket – You can use an UnLink pre-event handler to effectively move a
resource to a wastebasket instead of deleting it. Create a link in a wastebasket
folder before removing the original link. The link in the wastebasket ensures that
the resource is not removed. When you subsequently undelete a resource from the
waste basket, the original link can be created again and the wastebasket link
removed. The wastebasket link name can be different from the name of the link
being removed because a resource at a certain path could be unlinked more than
once from that path. The wastebasket would then have multiple links
corresponding to that path, with different link properties and possibly pointing to
different resources.
Categorization – An application might categorize the resources it manages based on
MIME type or other properties. It might keep track of GIF, text, and XML files by
maintaining links to them from repository folders /my-app/gif, /my-app/txt,
and /my-app/xml. Three post-event handlers could be used here: LinkIn,
UnlinkIn, and Update. The LinkIn post-event handler would examine the
resource and create a link in the appropriate category folder, if not already present.
The UnlinkIn post-event handler would remove the link from the category
Oracle XML DB Repository Events 30-1

Overview of Repository Events

folder. The Update post-event handler would effectively move the resource from
one category folder to another if its category changes.

Repository Events and Database Triggers
Repository events are reminiscent of database triggers, but they offer additional
functionality. You cannot use a database trigger to let your application react to
repository operations. A given repository operation can consist of multiple database
operations on multiple underlying, internal tables. Because these underlying tables are
internal to Oracle XML DB, you cannot easily map them to specific repository
operations. For example, internal table XDB$H_INDEX might be updated by either a
database update operation, if an ACL is changed, or a link operation. Even in cases
where you might be able to accomplish the same thing using database triggers, you
would not want to do that: A repository event is a higher-level abstraction than would
be a set of database triggers on the underlying tables.
When a repository event occurs, information associated with the operation, such as the
resource path used, can be passed to the corresponding event handler. Such
information is not readily available using database triggers.
Repository events and database triggers can both be applied to XML data. You can use
triggers on XMLType tables, for instance. However, if an XMLType table is also a
repository table (hierarchy-enabled), then do not duplicate in an event handler any
trigger code that applies to the table. Otherwise, that code is executed twice.

Repository Event Listeners and Event Handlers
Each repository operation is associated with one or more repository events. Your
application can configure listeners for the events associated with resources it is
concerned with. A repository event listener is a Java class or a PL/SQL package or
object type. It comprises a set of PL/SQL procedures or Java methods, each of which is
called an event handler. Each event handler processes a single event. A repository
event listener can be configured for a particular resource or for the entire repository. A
listener can be further restricted to apply only when a given node-existence
precondition is met.
You associate a repository event listener with a resource by mapping a resource
configuration file to the resource. You use PL/SQL package DBMS_RESCONFIG to
manipulate resource configuration files, including associating them with the resources
they configure. In particular, PL/SQL function DBMS_RESCONFIG.getListeners
lists all event listeners for a given resource.

Repository Event Configuration
A given resource can be configured by multiple resource configuration files. These are
stored in a resource configuration list, and they are processed in list order. The
repository as a whole can also be configured by multiple resource configuration files.
The repository itself has a resource configuration list. Event handling that is
configured for the repository as a whole takes effect before any resource-specific event
handling. All applicable repository-wide events are processed before any
resource-specific events.
A given resource configuration file can define multiple event listeners for the resources
it configures, and each event listener can define multiple event handlers.

30-2 Oracle XML DB Developer's Guide

Possible Repository Events

See Also:
■
■

"Configuring Repository Events" on page 30-8
"Resource Configuration Files Configure a Resource" on page 22-1
for general information about resource configuration and resource
configuration lists

Possible Repository Events
A rendering operation is associated with a single repository event. Except for
rendering, all repository operations are associated with one or more pairs of events. For
example, a resource creation is associated with three pairs of events, with the events
occurring in this order:
1.

Pre-creation event

2.

Post-creation event

3.

Pre-link-in event

4.

Pre-link-to event

5.

Post-link-to event

6.

Post-link-in event

Table 30–1 lists the events associated with each repository operation. Their order is
indicated in the handler columns.

Table 30–1

Predefined Repository Events

Repository Event Type Description
Render

A Render event occurs only for file
resources, never for folder resources.

Pre Handler Execution

Post Handler Execution

N/A

N/A

Occurs when resource contents are accessed
using any of the following:
■
■

Protocols
XDBURIType methods getCLOB(),
getBLOB(), and getXML()

Does not occur when resource contents are
accessed using any of the following:
■
■

SELECT ... FROM RESOURCE_VIEW
XDBURIType method
getResource()

Only one handler for a Render event can set
the rendered output. The first handler to call
setRenderStream or setRenderPath
controls the rendering.
Create

Occurs when a resource is created. The pre
and post handlers executed are those
defined on the folder of the new resource.

After pre-parsing, after
validating the parent
resource ACL and locks,
and before assigning
default values to undefined
properties.

After inserting the
resource into the system
resource table.

Delete

Occurs when the resource and its contents
are removed from disk, that is, when the
resource REF count is zero (0).

After validating the
resource ACL and locks and
before removing the
resource from disk.

After removing the
resource and its contents
from disk and after
touching the parent
folder to update its last
modifier and
modification time.

Oracle XML DB Repository Events 30-3

Possible Repository Events

Table 30–1 (Cont.) Predefined Repository Events
Repository Event Type Description

Pre Handler Execution

Post Handler Execution

Update

Occurs when a resource is updated on disk.

After writing the
After validating the
resource ACL and locks and resource to disk.
before updating the last
modifier and modification
time.

Lock

Occurs during a lock-resource operation.

After creating the new
After validating the
resource ACL and locks and lock.
before creating the new lock
on the resource.

Unlock

Occurs during an unlock-resource operation. After validating the
resource ACL and delete
token.

LinkIn

Occurs before a LinkTo event during a link
operation. The event target is the folder in
which the link is created. Always
accompanied by a LinkTo event.

After validating the
After executing LinkTo
resource ACL and locks and post handler.
before creating the link.

LinkTo

Occurs after a LinkIn event during a link
operation. The event target is the resource
that is the link destination.

After executing LinkIn pre After creating the link
handler and before creating and after updating the
the link.
last modifier and
modification time of the
parent folder.

UnLinkIn

Occurs before an UnlinkFrom event during
an unlink operation. Always accompanied
by an UnlinkFrom event.

After executing the
After validating the
resource ACL and locks and UnlinkFrom post
handler.
before removing the link.

UnlinkFrom

Occurs after an UnlinkIn event during an
unlink operation.

After executing the
UnlinkIn pre handler.

CheckIn

Occurs during check-in of a resource.

After checking in the
After validating the
resource ACL and locks and resource.
after verifying that the
resource is
version-controlled and has
been checked out.

CheckOut

Occurs during check-out of a resource.

After checking out the
After validating the
resource ACL and locks and resource.
after verifying that the
resource is
version-controlled and is
not already checked out.

UncheckOut

Occurs during uncheck-out of a resource.

Before removing the record
that the resource is checked
out.

After unchecking out the
resource.

VersionControl

Occurs when a version history is created for
a resource.

Before creating the version
history for the resource.

After creating the first
version of the resource.

After removing the lock.

After removing the link.

Note: You can call DBMS_
XDB.MakeVersioned() multiple times,
but the version history is created only at the
first call. Subsequent calls have no effect, so
no VersionControl event occurs.

For simplicity, the presentation in this chapter generally treats both members of a
repository event pair together, referring, for example, to the LinkIn event type as
shorthand for the pre-link-in and post-link-in event types. For the same reason, the
event-type names used here are derived from the Java interface
XDBRepositoryEventListener by dropping the prefixes handlePre and
handlePost.
See Also: Oracle Database PL/SQL Packages and Types Reference for the
PL/SQL repository event types

30-4 Oracle XML DB Developer's Guide

Repository Operations and Events

Repository Operations and Events
The same repository event can occur with different Oracle XML DB Repository
operations, and a given repository operation can produce more than one repository
event. Table 30–2 lists the events that are associated with each repository operation.
See Table 30–1 for the event order when multiple repository events occur for the same
operations.
Table 30–2

Oracle XML DB Repository Operations and Events

Operation

Repository Events Occurring

Get binary representation of resource contents by path name

Render

Get XML representation of resource contents by path name

Render

Create or update a resource

If the resource already exists: Create, LinkIn,
LinkTo
If resource doe not yet exist (HTTP and FTP only):
Update

Create a folder

Create, LinkIn, LinkTo

Create a link to an existing resource

LinkIn on the folder containing the link target,
LinkTo on the target resource to be linked

Unlink a file resource or an empty folder resource.
(Decrement RefCount, and if it becomes zero then delete the
resource from disk.)

UnlinkIn, UnlinkFrom, and, if RefCount is
zero, Delete

Forcibly delete a folder and its contents

Recursively produce events for unlinking a
resource. Folder child resources are deleted
recursively, then the folder is deleted.

Forcibly remove all links to a resource

Produce unlinking events for each link removed.

Update the contents, properties, or ACL of a resource by path
name

Update

Put a depth-zero WebDAV lock on a resource

Lock

Remove a depth-zero WebDAV lock from a resource

Lock

Rename (move) a resource

LinkIn and LinkTo on the new location,
UnlinkIn and UnlinkFrom on the old location

Copy a resource

Create, LinkIn, and LinkTo on the new
location

Check out a resource

CheckOut

Check in a resource

CheckIn

Place a resource under version control

VersionControl

Uncheck out a resource

UncheckOut

All operations listed in Table 30–2 are atomic, except for these:
■

Forced deletion of a folder and its contents

■

Update of resource properties by path name using HTTP (only)

■

Copy of a folder using HTTP (only)
See Also: Table 21–3, " Accessing Oracle XML DB Repository: API
Options" on page 21-15 for information on accessing resources using
APIs and protocols

Oracle XML DB Repository Events 30-5

Repository Event Handler Considerations

Repository Event Handler Considerations
This section mentions some things to keep in mind when you define handlers for
Oracle XML DB Repository events.
■

In any handler: Do not use COMMIT, ROLLBACK, or data definition language (DDL)
statements in a handler. Do not call PL/SQL functions or procedures, such as
DBMS_XMLSCHEMA.registerSchema, that behave similarly to DDL statements.
In a Render handler: Do not use data manipulation language (DML) statements.
To work around these restrictions, a handler can use such statements inside an
autonomous transaction, but it must ensure that lock conflicts cannot arise.

■
■

■

■

■

■

■

■

■

■

■

In a Render handler, do not close an output stream. (You can append to a stream.)
Do not use modifier methods from class XDBResource in a handler, unless it is a
Pre-Create or Pre-Update handler. Do not use method
XDBResource.save() in any handler.
Oracle recommends that you develop only safe repository event handlers. In
particular:
–

Write only resource properties that are in namespaces owned by your
application, never in the xdb namespace.

–

Do not delete a resource while it is being created.

A repository event handler is passed an XDBRepositoryEvent object, which
exists only during the current SQL statement or protocol operation. You can use
PL/SQL procedures and Java methods on this object to obtain information about
the resource, the event, and the associated event handlers.
When an event handler performs operations that cause other repository events to
occur, those cascading events occur immediately. They are not queued to occur
after the handlers for the current event are finished. Each event thus occurs in the
context of its corresponding operation.
Repository event handlers are called synchronously. They are executed in the
process, session, and transaction context of the corresponding operation. However,
handlers can use Oracle Streams Advanced Queuing (AQ) to queue repository
events that are then handled asynchronously by some other process.
Because a repository event handler is executed in the transaction context of its
corresponding operation, any locks acquired by that operation, or by other
operations run previously in the transaction, are still active. An event handler
must not start a separate session or transaction that tries to acquire such a lock.
Otherwise, the handler hangs.
Repository event handlers are called in the order that they appear in a resource
configuration file. If preconditions are defined for a resource configuration, then
only those handlers are called for which the precondition is satisfied.
Although handlers are called in the order they are defined in a configuration file,
avoid letting your code depend upon this. If the user who is current when a
handler is invoked has privilege write-config, then the handler invocation
order could be changed inside an executing handler.
The entire list of handlers applicable to a given repository event occurrence is
determined before any of the handlers is invoked. This means, in particular, that
the precondition for each handler is evaluated before any handlers are invoked.
The following considerations apply to error handling for repository events:

30-6 Oracle XML DB Developer's Guide

Repository Event Handler Considerations

■

■

■

–

A pre-operation event handler is never invoked if access checks for the
operation fail.

–

All handlers for a given event are checked before any of them are called. If any
of them is not usable (for example, no longer exists), then none of them are
called.

–

If an error is raised during event handling, then other, subsequent event
handlers are not invoked for the same SQL statement or protocol operation.
The current statement or operation is canceled and all of its changes are rolled
back.

The following considerations apply to resource security for repository events:
–

An event handler can have invoker's rights or definer rights. You specify the
execution rights of a PL/SQL package when you create the package. You
specify the execution rights of Java classes when you load them into the
database using the loadjava utility. If you specify invoker's rights, but a
given handler is not configured for invoker's rights, then an
insufficient-privilege error is raised.

–

Within an event handler, the current user privileges, whether obtained by
invoker or definer rights, are determined in detail for a given resource by its
ACL. These privileges determine what the handler can do with the resource.
For example, if the current user has privileges read-properties and
read-contents for a particular resource, then an event handler can read that
resource.

The following considerations apply to repository events for linking and unlinking:
–

After creating a link to a resource, if you want any resource configuration files
of the parent folder to also apply to the linked resource, then use procedure
DBMS_RESCONFIG.appendResConfig to add the configuration files to the
linked resource. You can invoke this procedure from a Post-LinkTo event
handler for the linked resource.

–

After unlinking a resource, if you want to remove any such resource
configuration files added when linking, then use procedure DBMS_
RESCONFIG.deleteResConfig to remove them from the unlinked resource.
You can invoke this procedure from a Post-UnlinkFrom event handler for
the unlinked resource.

Do not define handlers for events on folder /sys/schemas or on resources under
this folder. Events do not occur for any such resources, so such event handlers are
ignored. This implies that XML schema operations that affect the repository
(registration, deletion, and so on) do not produce events.
See Also:
■

■

■

Oracle Database PL/SQL Packages and Types Reference for
information about PL/SQL functions and procedures for
manipulating repository events
Oracle Database XML Java API Reference, classes
XDBRepositoryEvent and XDBEvent for information about
Java methods for manipulating repository events
"Configuring Repository Events" on page 30-8 for information
about defining repository event handlers with invoker's rights

Oracle XML DB Repository Events 30-7

Configuring Repository Events

Configuring Repository Events
You configure event treatment for Oracle XML DB Repository resources as you would
configure any other treatment of repository resources—see "Configuring a Resource"
on page 22-2.
By default, repository events are enabled, but you can disable them by setting
parameter XML_DB_EVENTS to DISABLE. To disable repository events at the session
level, use the following SQL*Plus command. You must have role XDBADMIN to do this.
ALTER SESSION SET XML_DB_EVENTS = DISABLE;

To disable repository events at the system level, use the following SQL*Plus command,
and then restart your database. Repository events are disabled for subsequent
sessions. You must have privilege ALTER SYSTEM to do this.
ALTER SYSTEM SET XML_DB_EVENTS = DISABLE;

To enable repository events again, set the value of XML_DB_EVENTS to ENABLE.
The rest of this section describes the resource configuration file that you use as a
resource to configure event processing for other resources.
A resource configuration file is an XML file that conforms to the XML schema
XDBResConfig.xsd, which is accessible in Oracle XML DB Repository at path
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/XDBResConfig.xsd. You use
element event-listeners, child of element ResConfig, to configure repository
event handling.
See Also: Chapter 22, "Configuring Oracle XML DB Repository" for
general information about configuring repository resources

Configuration Element event-listeners
Each resource configuration file can have one event-listeners element, as a child
of element ResConfig. This configures all event handling for the target resource. If
the resource configuration file applies to the entire repository, not to a particular
resource, then it defines event handling for all resources in the repository.
Element event-listeners has the following optional attributes:
■

set-invoker – Set this to true to if the resource configuration defines one or
more repository event handlers to have invoker's rights. The default value is
false, meaning that definer rights are used.
To define an invoker-rights repository event handler, you must have database role
XDB_SET_INVOKER. This role is granted to DBA, but not to XDBADMIN. Role XDB_
SET_INVOKER is checked only when a resource configuration file is created or
updated. Only attribute set-invoker, not role XDB_SET_INVOKER, is checked
at run time to ensure sufficient privilege.
See Also: "Repository Event Handler Considerations" on page 30-6
for information about insufficient-privilege errors

■

■

default-schema – The default schema value, used for listeners for which no
schema element is defined.
default-language –The default language value, used for listeners for which no
language element is defined.

30-8 Oracle XML DB Developer's Guide

Configuring Repository Events

Element event-listeners has a sequence of listener elements as children. These
configure individual repository event listeners. The listeners are processed at run time
in the order of the listener elements.

Configuration Element listener
Each listener element has the following child elements. All of these are optional
except source, and they can appear in any order (their order is irrelevant).
■
■

■

■

■

■

description – Description of the listener.
schema – Database schema for the Java or PL/SQL implementation of the
repository event handlers. If neither this nor default-schema is defined, then an
error is raised.
source (required) – Name of the Java class, PL/SQL package, or object type that
provides the handler methods. Java class names must be qualified with a package
name. Use an empty source element to indicate that the repository event
handlers are standalone PL/SQL stored procedures.
language – Implementation language of the listener class (Java) or package
(PL/SQL). If neither this nor default-language is defined, then an error is
raised.
pre-condition – Precondition to be met for any repository event handlers in
this listener to be executed. This is identical to the pre-condition child of
general resource configuration element configuration – see "Configuration
Element defaultChildConfig" on page 22-3.
events – Sequence of unique repository event type names: Render,
Pre-Create, and so on. Only handlers for repository events of these types are
enabled for the listener. See "Possible Repository Events" on page 30-3 for the list
of possible repository event types. If element events is not present, then handlers
of repository events of all types are enabled for the listener, which can be wasteful.
Provide element events to eliminate handler invocations for insignificant
repository events.

Repository Events Configuration Examples
Example 30–1 shows the content of a resource configuration file that defines two
listeners. Each listener defines handlers for repository events of types Post-LinkIn,
Post-UnlinkIn, and Post-Update. It defines preconditions, the default language
(Java) and default database schema.
Example 30–1

Resource Configuration File for Java Event Listeners with Preconditions




Category application
CM
oracle.cm.category






Oracle XML DB Repository Events 30-9

Configuring Repository Events



/Resource[ContentType="image/gif"]




Check quota
oracle.ifs.quota







r:/Resource/[ns:type="ifs-file"]
xmlns:r="http://xmlns.oracle.com/xdb/XDBResource.xsd"
xmlns:ns="http://foo.xsd"







/sys/xdb/resconfig/user_rc.xml




1234




The implementation of the handlers of the first listener is in Java class
oracle.cm.quota defined in database schema CM. These handlers are invoked only
for events on resources of ContentType image/gif.
The implementation of the handlers of the second listener is in Java class
oracle.ifs.quota defined in database schema IFS (the default schema for this
resource configuration file). These handlers are invoked only for events on resources of
type ifs-file in namespace http://foo.xsd.
"Configuration Element defaultChildConfig" on page 22-3
for a description of elements defaultChildConfig and
applicationData
See Also:

As a simple end-to-end illustration, suppose that an application needs to categorize
the resources in folder /public/res-app according to their MIME types. It creates
links to resources in folders /public/app/XML-TXT, /public/app/IMG, and
/public/app/FOLDER, depending on whether the resource MIME type is
text/xml, image/gif, or application/octet-stream, respectively. This is
illustrated in Example 30–2, Example 30–3, and Example 30–5.
Example 30–2 shows the PL/SQL code to create the configuration file for this
categorization illustration. It defines a single listener that handles events of types

30-10 Oracle XML DB Developer's Guide

Configuring Repository Events

Pre-UnlinkIn and Post-LinkIn. It explicitly defines the language (PL/SQL) and
database schema. No preconditions are defined.
Example 30–2

Resource Configuration File for PL/SQL Event Listeners with No Preconditions

DECLARE
b BOOLEAN := FALSE;
BEGIN
b := DBMS_XDB.createFolder('/public/resconfig');
b := DBMS_XDB.createResource(
'/public/resconfig/appcatg-rc1.xml',
'


Category application
APPCATGUSER1
APPCATG_EVT_PKG1
PL/SQL








/public/resconfig/appcatg-rc1.xml


',
'http://xmlns.oracle.com/xdb/XDBResConfig.xsd',
'ResConfig');
END;
/
BEGIN
DBMS_RESCONFIG.appendResConfig('/public/res-app',
'/public/resconfig/appcatg-rc1.xml',
DBMS_RESCONFIG.APPEND_RECURSIVE);
END;
/

Example 30–3 shows the PL/SQL code that implements the event handlers that are
configured in Example 30–2. The Post-LinkIn event handler creates a link to the
eventObject resource in one of the folders /public/app/XML-TXT,
/public/app/IMG, and /public/app/FOLDER, depending on the resource MIME
type. The Pre-UnlinkIn event handler deletes the links that are created by the
Post-LinkIn event handler.
Example 30–3

PL/SQL Code Implementing Event Listeners

CREATE OR REPLACE PACKAGE appcatg_evt_pkg1 AS
PROCEDURE handlePreUnlinkIn (eventObject DBMS_XEVENT.XDBRepositoryEvent);
PROCEDURE handlePostLinkIn (eventObject DBMS_XEVENT.XDBRepositoryEvent);
END;
/

Oracle XML DB Repository Events 30-11

Configuring Repository Events

CREATE OR REPLACE PACKAGE BODY appcatg_evt_pkg1 AS
PROCEDURE handlePreUnlinkIn (eventObject DBMS_XEVENT.XDBRepositoryEvent) AS
XDBResourceObj DBMS_XDBRESOURCE.XDBResource;
ResDisplayName VARCHAR2(100);
ResPath
VARCHAR2(1000);
ResOwner
VARCHAR2(1000);
ResDeletedBy
VARCHAR2(1000);
XDBPathobj
DBMS_XEVENT.XDBPath;
XDBEventobj
DBMS_XEVENT.XDBEvent;
SeqChar
VARCHAR2(1000);
LinkName
VARCHAR2(10000);
ResType
VARCHAR2(100);
LinkFolder
VARCHAR2(100);
BEGIN
XDBResourceObj := DBMS_XEVENT.getResource(eventObject);
ResDisplayName := DBMS_XDBRESOURCE.getDisplayName(XDBResourceObj);
ResOwner
:= DBMS_XDBRESOURCE.getOwner(XDBResourceObj);
XDBPathobj
:= DBMS_XEVENT.getPath(eventObject);
ResPath
:= DBMS_XEVENT.getName(XDBPathObj);
XDBEventobj
:= DBMS_XEVENT.getXDBEvent(eventObject);
ResDeletedBy
:= DBMS_XEVENT.getCurrentUser(XDBEventobj);
BEGIN
SELECT XMLCast(
XMLQuery(
'declare namespace ns = "http://xmlns.oracle.com/xdb/XDBResource.xsd";
/ns:Resource/ns:ContentType'
PASSING r.RES RETURNING CONTENT) AS VARCHAR2(100))
INTO ResType
FROM PATH_VIEW r WHERE r.PATH=ResPath;
EXCEPTION WHEN OTHERS THEN NULL;
END;
IF ResType = 'text/xml' THEN LinkFolder := '/public/app/XML-TXT/';
END IF;
IF ResType = 'image/gif' THEN LinkFolder := '/public/app/IMG/';
END IF;
IF ResType = 'application/octet-stream' THEN LinkFolder := '/public/app/FOLDER/';
END IF;
DBMS_XDB.deleteResource(LinkFolder || ResDisplayName);
END;
PROCEDURE handlePostLinkIn (eventObject DBMS_XEVENT.XDBRepositoryEvent) AS
XDBResourceObj DBMS_XDBRESOURCE.XDBResource;
ResDisplayName VARCHAR2(100);
ResPath
VARCHAR2(1000);
ResOwner
VARCHAR2(1000);
ResDeletedBy
VARCHAR2(1000);
XDBPathobj
DBMS_XEVENT.XDBPath;
XDBEventobj
DBMS_XEVENT.XDBEvent;
SeqChar
VARCHAR2(1000);
LinkName
VARCHAR2(10000);
ResType
VARCHAR2(100);
LinkFolder
VARCHAR2(100);
BEGIN
XDBResourceObj := DBMS_XEVENT.getResource(eventObject);
ResDisplayName := DBMS_XDBRESOURCE.getDisplayName(XDBResourceObj);
ResOwner
:= DBMS_XDBRESOURCE.getOwner(XDBResourceObj);
XDBPathobj
:= DBMS_XEVENT.getPath(eventObject);
ResPath
:= DBMS_XEVENT.getName(XDBPathObj);
XDBEventobj
:= DBMS_XEVENT.getXDBEvent(eventObject);

30-12 Oracle XML DB Developer's Guide

Configuring Repository Events

ResDeletedBy
:= DBMS_XEVENT.getCurrentUser(XDBEventobj);
SELECT XMLCast(
XMLQuery(
'declare namespace ns = "http://xmlns.oracle.com/xdb/XDBResource.xsd";
/ns:Resource/ns:ContentType'
PASSING r.RES RETURNING CONTENT) AS VARCHAR2(100))
INTO ResType
FROM PATH_VIEW r WHERE r.PATH=ResPath;
IF ResType = 'text/xml' THEN LinkFolder := '/public/app/XML-TXT';
END IF;
IF ResType = 'image/gif' THEN LinkFolder := '/public/app/IMG';
END IF;
IF ResType = 'application/octet-stream' THEN LinkFolder := '/public/app/FOLDER';
END IF;
DBMS_XDB.link(ResPath, LinkFolder, ResDisplayName);
END;
END;
/

See Also:
■

■

Oracle Database PL/SQL Packages and Types Reference for
information about PL/SQL package DBMS_XDBRESOURCE
Oracle Database PL/SQL Packages and Types Reference for
information about PL/SQL package DBMS_XEVENT

A Java example would be configured the same as in Example 30–2, with the exception
of these two lines, which would replace the elements with the same names in
Example 30–2:
category
Java

Example 30–4 shows the Java code that implements the event handlers. The logic is
identical to that in Example 30–3.
Example 30–4
import
import
import
import
import
import
import
import
import

Java Code Implementing Event Listeners

oracle.xdb.event.*;
oracle.xdb.spi.*;
java.sql.*;
java.io.*;
java.net.*;
oracle.jdbc.*;
oracle.sql.*;
oracle.xdb.XMLType;
oracle.xdb.dom.*;

public class category
extends oracle.xdb.event.XDBBasicEventListener
{
public Connection connectToDB() throws java.sql.SQLException
{
try
{
String strUrl="jdbc:oracle:kprb:";
String strUname="appcatguser1";
String strPwd="appcatguser1 ";
Connection conn=null;

Oracle XML DB Repository Events 30-13

Configuring Repository Events

OraclePreparedStatement stmt=null;
DriverManager.registerDriver(new oracle.jdbc.OracleDriver());
conn = DriverManager.getConnection(strUrl, strUname, strPwd);
return conn;
}
catch(Exception e1)
{
System.out.println("Exception in connectToDB java function");
System.out.println("e1:" + e1.toString());
return null;
}
}
public void handlePostLinkIn (XDBRepositoryEvent eventObject)
{
XDBPath objXDBPath = null;
String strPathName="";
objXDBPath = eventObject.getPath();
strPathName = objXDBPath.getName();
XDBResource objXDBResource1;
objXDBResource1 = eventObject.getResource();
String textResDisplayName = objXDBResource1.getDisplayName();
String resType = objXDBResource1.getContentType();
String linkFolder="";
System.out.println("resType" + resType+"sumit");
System.out.println("strPathName:" + strPathName);
System.out.println("textResDisplayName:" + textResDisplayName);
if (resType.equals("text/xml")) linkFolder = "/public/app/XML-TXT/";
else if (resType.equals("image/gif")) linkFolder = "/public/app/IMG/";
else if (resType.equals("application/octet-stream"))
linkFolder = "/public/app/FOLDER/";
System.out.println("linkFolder:" + linkFolder);
try
{
Connection con1 = connectToDB();
OraclePreparedStatement stmt=null;
stmt = (OraclePreparedStatement)con1.prepareStatement(
"CALL DBMS_XDB.link(?,?,?)");
stmt.setString(1,strPathName);
stmt.setString(2,linkFolder);
stmt.setString(3,textResDisplayName);
stmt.execute();
stmt.close();
con1.close();
}
catch(java.sql.SQLException ej1)
{
System.out.println("ej1:" + ej1.toString());
}
/* Make sure the link is not in the category folders.
Then check the target resource's mime type and create a link
in the appropriate category folder. */
}
public void handlePreUnlinkIn (XDBRepositoryEvent eventObject)
{
XDBPath objXDBPath = null;
String strPathName="";
objXDBPath = eventObject.getPath();
strPathName = objXDBPath.getName();
XDBResource objXDBResource1;

30-14 Oracle XML DB Developer's Guide

Configuring Repository Events

objXDBResource1 = eventObject.getResource();
String textResDisplayName = objXDBResource1.getDisplayName();
String resType = objXDBResource1.getContentType();
String linkFolder="";
if (resType.equals("text/xml")) linkFolder = "/public/app/XML-TXT/";
else if (resType.equals("image/gif")) linkFolder = "/public/app/IMG/";
else if (resType.equals("application/octet-stream"))
linkFolder = "/public/app/FOLDER/";
try
{
Connection con1 = connectToDB();
OraclePreparedStatement stmt=null;
stmt = (OraclePreparedStatement)con1.prepareStatement(
"CALL DBMS_XDB.deleteResource(?)");
stmt.setString(1,linkFolder+textResDisplayName);
stmt.execute();
stmt.close();
con1.close();
}
catch(java.sql.SQLException ej1)
{
System.out.println("ej1:" + ej1.toString());
}
}
}

Example 30–5 demonstrates the invocation of the event handlers that are implemented
in Example 30–3 or Example 30–4.
Example 30–5

Invoking Event Handlers

DECLARE
ret BOOLEAN;
BEGIN
ret := DBMS_XDB.createResource('/public/res-app/res1.xml',
'TestForEventType-1');
END;
/
DECLARE
b BOOLEAN := FALSE;
dummy_data CLOB := 'AAA';
BEGIN
b := DBMS_XDB.createResource('/public/res-app/res2.gif', dummy_data);
END;
/
DECLARE
b BOOLEAN := FALSE;
dummy_data CLOB := 'AAA';
BEGIN
b := DBMS_XDB.createFolder('/public/res-app/res-appfolder1');
END;
SELECT PATH FROM PATH_VIEW WHERE PATH LIKE '/public/app/%' ORDER BY PATH;
PATH
--------------------------------/public/app/FOLDER
/public/app/FOLDER/res-appfolder1
/public/app/IMG
/public/app/IMG/res2.gif

Oracle XML DB Repository Events 30-15

Configuring Repository Events

/public/app/XML-TXT
/public/app/XML-TXT/res1.xml
6 rows selected.
-- Delete the /res-app resources. The /app resources are deleted also.
EXEC DBMS_XDB.deleteResource('/public/res-app/res2.gif');
EXEC DBMS_XDB.deleteResource('/public/res-app/res1.xml');
EXEC DBMS_XDB.deleteResource('/public/res-app/res-appfolder1');
SELECT PATH FROM PATH_VIEW WHERE PATH LIKE '/public/app/%' ORDER BY PATH;
PATH
------------------/public/app/FOLDER
/public/app/IMG
/public/app/XML-TXT
3 rows selected.

30-16 Oracle XML DB Developer's Guide

31
Using Oracle XML DB Content Connector
This chapter describes how to use Oracle XML DB Content Connector to access Oracle
XML DB Repository.
Oracle XML DB Content Connector implements Content Repository API for Java
(sometimes referred to as JCR), a Java API standard developed by the Java community
as JSR-170.
This chapter contains these topics:
■

Overview of JCR and Oracle XML DB Content Connector

■

How Oracle XML DB Repository Is Exposed in JCR

■

How to Use Oracle XML DB Content Connector

■

Using XML Schemas with JCR

Overview of JCR and Oracle XML DB Content Connector
This section contains the following topics:
■

About the Content Repository API for Java (JCR)

■

About Oracle XML DB Content Connector

About the Content Repository API for Java (JCR)
JCR 1.0 defines a standard Java API for applications to interact with content
repositories.
See Also: Java Community Process, "Content Repository for Java
technology API", http://jcp.org/en/jsr/detail?id=170.
Chapter 4 of the JSR-170 specification provides a concise introduction
to JCR 1.0

JCR models the data in a content repository as a tree of nodes. Each node may have
one or more child nodes. Every node has exactly one parent node, except for the root
node, which has no parent.
In addition to child nodes, a node may also have one or more properties. A property is
a simple name/value pair. For example, a node representing a particular file in the
content repository has a property named jcr:created whose value is the date the
file was created.
Each property has a property type. For example, the jcr:created property has the
DATE property type, requiring its value to be a valid date/time.

Using Oracle XML DB Content Connector 31-1

How Oracle XML DB Repository Is Exposed in JCR

Similarly, each node has a node type. For example, a node representing a file has node
type nt:file. The node type controls what child nodes and properties the node may
have or must have. For example, all nodes of type nt:file must have a
jcr:created property.
Because nodes and properties are named, they can be addressed by path. JCR supports
both absolute and relative paths. For example, the absolute path
/My Documents/pictures/puppy.jpg/jcr:created

resolves to the jcr:created property of file puppy.jpg. This property can also be
addressed relative to the My Documents folder by the following relative path:
pictures/puppy.jpg/jcr:created

Node and property names can be namespace qualified. Like XML, JCR uses
colon-delimited namespace prefixes to express namespace-qualified names, for
example, jcr:created. Unlike XML, JCR records the namespace prefix-to-URI
mappings in a repository-wide namespace registry, which, for example, maps the jcr
prefix to the URI http://www.jcp.org/jcr/1.0.

About Oracle XML DB Content Connector
Oracle XML DB Content Connector lets you access Oracle XML DB Repository using
the JCR 1.0 Java API. Your applications can run either in a standalone Java Virtual
Machine or a J2EE container.
Using Oracle XML DB Content Connector in the database
Oracle JVM (the Java Virtual Machine available within a database
process) is not supported. To use the content connector in the database
tier, you must use either a standalone Java Virtual Machine or a J2EE
container.

Note:

Files and folders in Oracle XML DB Repository are represented as JCR nodes (and
properties of those nodes). They can be created, retrieved, and updated using the JCR
APIs.

How Oracle XML DB Repository Is Exposed in JCR
Oracle XML DB Content Connector represents data in Oracle XML DB Repository as
JCR nodes and properties. Files and folders are represented as nodes of type nt:file
and nt:folder, respectively. Their content and metadata is exposed as nodes of node
type nt:resource.
This section contains the following topics:
■

Example of How Files and Folders are Exposed in JCR

■

Oracle Extensions to JCR Node Types

■

Binary and XML Content

■

System-Defined Metadata

■

User-Defined Metadata

■

Hard Links and Weak Links

31-2 Oracle XML DB Developer's Guide

How Oracle XML DB Repository Is Exposed in JCR

Example of How Files and Folders are Exposed in JCR
The folder MyFolder is stored in the root folder of Oracle XML DB Repository. It
contains two files, Address.xml and Car.jpg.
File Address.xml has the following XML content:

Alice Smith
123 Maple Street
Mill Valley
CA
90952


File Car.jpg has binary content: a picture of an automobile. It also has the following
user-defined XML metadata:

640
480



Oracle XML DB Content Connector exposes MyFolder, Address.xml, and Car.jpg
as JCR nodes and properties.
Example 31–1 shows folder MyFolder represented as a tree of JCR nodes and
properties. In this representation, bold type indicates a node, italic type indicates a
node type, regular type indicates a property, and italic type with angle brackets (<>)
indicates omitted data, such as binary data.
Example 31–1

JCR Node Representation of MyFolder

[root] (nt:folder)
jcr:created="2001-01-01T00:00:00.000Z"
jcr:content (nt:resource)
jcr:data=null
jcr:lastModified="2001-01-01T00:00:00.000Z"
ojcr:owner="SYS"
ojcr:creator="SYS"
ojcr:lastModifier="SYS"
ojcr:displayName=""
ojcr:language="en-US"
MyFolder (nt:folder)
jcr:created="2001-01-01T00:00:00.000Z"
jcr:content (nt:resource)
jcr:data=null
jcr:lastModified="2001-01-01T00:00:00.000Z"
ojcr:owner="ALICE"
ojcr:creator="BOB"
ojcr:lastModifier="CHARLIE"
ojcr:author="BOB"
ojcr:comment="An application folder"
ojcr:displayName="MyFolder"
ojcr:language="en-US"
ojcr:links (ojcr:links)
ojcr:folderLink (ojcr:linkProperties)
ojcr:linkType="Hard"
ojcr:linkSource=
ojcr:linkTarget=
ojcr:linkName="MyFolder"
Using Oracle XML DB Content Connector 31-3

How Oracle XML DB Repository Is Exposed in JCR

Address.xml (nt:file)
jcr:created="2005-09-01T12:34:56.789Z"
jcr:content (nt:resource)
jcr:encoding="UTF-8"
jcr:mimeType="text/xml"
jcr:data=
jcr:lastModified="2005-09-01T12:34:56.789Z"
ojcr:owner="ALICE"
ojcr:creator="BOB"
ojcr:lastModifier="CHARLIE"
ojcr:author="BOB"
ojcr:displayName="Address.xml"
ojcr:language="en-US"
ojcr:xmlContent (nt:unstructured)
Address
country="US"
name
jcr:xmltext
jcr:xmlcharacters="Alice Smith"
street
jcr:xmltext
jcr:xmlcharacters="123 Maple Street"
city
jcr:xmltext
jcr:xmlcharacters="Mill Valley"
state
jcr:xmltext
jcr:xmlcharacters="CA"
zip
jcr:xmltext
jcr:xmlcharacters="90952"
ojcr:links (ojcr:links)
ojcr:folderLink (ojcr:linkProperties)
ojcr:linkType="Hard"
ojcr:linkSource=
ojcr:linkTarget=
ojcr:linkName="Address.xml"
Car.jpg (nt:file)
jcr:created="2004-02-12T16:15:23.247Z"
jcr:content (nt:resource)
jcr:mimeType="image/jpeg"
jcr:data=
jcr:lastModified="2004-02-12T17:20:25.314Z"
ojcr:owner="ALICE"
ojcr:creator="BOB"
ojcr:lastModifier="CHARLIE"
ojcr:author="BOB"
ojcr:displayName="A shiny red car!"
ojcr:language="en-US"
i:ImageMetadata
Height
jcr:xmltext
jcr:xmlcharacters="640"
Width
jcr:xmltext
jcr:xmlcharacters="480"
RGB
R="44"
G="123"
B="74"

31-4 Oracle XML DB Developer's Guide

How Oracle XML DB Repository Is Exposed in JCR

ojcr:links (ojcr:links)
ojcr:folderLink (ojcr:linkProperties)
ojcr:linkType="Hard"
ojcr:linkSource=
ojcr:linkTarget=
ojcr:linkName="Car.jpg"

Oracle Extensions to JCR Node Types
Oracle XML DB Content Connector augments the definitions of node types nt:file,
nt:folder, and nt:resource to include additional information held in Oracle
XML DB Repository. Node type ojcr:folder is added as a supertype of
nt:folder, and node type ojcr:resource is added as a supertype of
nt:resource. All Oracle extensions are in the namespace
http://xmlns.oracle.com/jcr/1.0, which is mapped to namespace prefix
ojcr.
In addition, node type mix:referenceable is added as a supertype of nt:file
and nt:folder to allow all files and folders to be accessed by their resource id.

Binary and XML Content
Property jcr:data contains the binary content of a file. Note that jcr:data is a
property not of node nt:file, but rather of its child node jcr:content.
For files containing XML content, node jcr:content has a child node
ojcr:xmlContent, under which the XML content can be accessed as a set of JCR
nodes and properties. File Address.xml, referenced in Example 31–1 on page 31-3, is
such a file. The XML content of an XML file in the repository is mapped to JCR nodes
and properties using the document view serialization defined by JCR, in which:
■

XML elements are exposed as JCR nodes.

■

XML attributes are exposed as JCR properties.

■

XML text is exposed as JCR properties named jcr:xmlcharacters within
nodes named jcr:xmltext.

System-Defined Metadata
Oracle XML DB Repository maintains metadata for each repository file and folder. In
database views RESOURCE_VIEW and PATH_VIEW, this metadata is represented as a
set of XML elements within XMLType column RES. In JCR, this metadata is mapped to
properties in namespaces jcr and ojcr. Table 31–1 describes this mapping.
Table 31–1

Oracle XML DB Resource to JCR Mappings

XPath

Relative Path From Node nt:file or nt:folder

/Resource/CreationDate

jcr:created

/Resource/ModificationDate

jcr:content/jcr:lastModified

/Resource/Author

jcr:content/ojcr:author

/Resource/DisplayName

jcr:content/ojcr:displayName

/Resource/Comment

jcr:content/ojcr:comment

/Resource/Language

jcr:content/ojcr:language

/Resource/CharacterSet

jcr:content/jcr:encoding

Using Oracle XML DB Content Connector 31-5

How Oracle XML DB Repository Is Exposed in JCR

Table 31–1 (Cont.) Oracle XML DB Resource to JCR Mappings
XPath

Relative Path From Node nt:file or nt:folder

/Resource/ContentType

jcr:content/jcr:mimeType

/Resource/Owner

jcr:content/ojcr:owner

/Resource/Creator

jcr:content/ojcr:creator

/Resource/LastModifier

jcr:content/ojcr:lastModifier

User-Defined Metadata
User-defined XML metadata is exposed as JCR nodes and properties under the
jcr:content child node of the repository file or folder. As with XML file content,
XML metadata is mapped to JCR nodes and properties using the document view
serialization that is defined by JCR. See "Binary and XML Content" on page 31-5 for a
description of this serialization.
In Example 31–1, file Car.jpg has this user-defined metadata:

640
480



The following JCR path retrieves the Width value:
/My Folder/Car.jpg/jcr:content/i:ImageMetadata/
Width/jcr:xmltext/jcr:xmlcharacters

Hard Links and Weak Links
In JCR, each node and property has exactly one parent node, except for the root node,
which has no parent. Consequently, there is exactly one absolute path to each JCR
node or property.
However, in Oracle XML DB Repository, a resource (file or folder) can be linked to
more than one parent folder, either by hard links, which control the life span of the
child, or by weak links, which do not. Consequently, there can be more than one path
to a resource, and a resource can have more than one parent.
In resolving a path, Oracle XML DB Content Connector traverses both hard and weak
links. If there is more than one path to a resource, JCR method getPath() returns the
path by which that resource was first discovered, subsequent to the most recent call to
either save() or refresh(boolean) by that session. JCR method getParent()
returns the folder targeted by that path.
It is often useful to obtain a list of all parents of a resource, if the resource is the target
of more than one link and therefore has more than one parent folder. Oracle XML DB
Content Connector presents this as nodes of type ojcr:linkProperties with path
jcr:content/ojcr:links/ojcr:folderLink relative to node nt:file or
nt:folder. There is one ojcr:folderLink node for each parent of the resource.
Node ojcr:folderLink has the following properties:
■

ojcr:linkType: Link type (Hard or Weak)

■

ojcr:linkSource: Resource id of the parent folder

■

ojcr:linkTarget: Resource id of the child file or folder

31-6 Oracle XML DB Developer's Guide

How to Use Oracle XML DB Content Connector

■

ojcr:linkName: Name of the child file or folder in that parent

How to Use Oracle XML DB Content Connector
This section describes how to use Oracle XML DB Content Connector to access
information in Oracle XML DB Repository. It has the following topics:
■

Setting CLASSPATH

■

Obtaining the JCR Repository Object

■

Sample Code to Upload File

■

Additional Code Samples

■

Logging API for Oracle XML DB Content Connector

■

Supported JCR Compliance Levels

■

Oracle XML DB Content Connector Restrictions

Setting CLASSPATH
Oracle XML DB Content Connector requires the following entries in the Java
CLASSPATH variable:
■

$ORACLE_HOME/lib/jcr-1.0.jar

■

$ORACLE_HOME/lib/ojcr.jar

■

$ORACLE_HOME/lib/xmlparserv2.jar

■

$ORACLE_HOME/jlib/xquery.jar

Obtaining the JCR Repository Object
In Oracle XML DB Content Connector, oracle.jcr.OracleRepository
implements the JCR interface javax.jcr.Repository, which provides the entry
point to a JCR repository. The code fragment in Example 31–2 shows how to obtain a
Repository object for Oracle XML DB Repository.
Example 31–2

Code Fragment Showing How to Get a Repository Object

import oracle.jcr.OracleRepository;
import oracle.jcr.OracleRepositoryFactory;
import oracle.jcr.xdb.XDBRepositoryConfiguration;
import oracle.jdbc.pool.OracleDataSource;
...
XDBRepositoryConfiguration configuration =
new XDBRepositoryConfiguration();
OracleDataSource ods =
(OracleDataSource)configuration.getDataSource();
// databaseURL is a JDBC database URL.
ods.setURL(databaseURL);
// OracleRepository implements javax.jcr.Repository.
OracleRepository repository =
OracleRepositoryFactory.createOracleRepository(configuration);

OracleRepository implements both java.io.Serializable and
javax.naming.Referenceable. This lets you create and configure an
OracleRepository object upon application deployment, and store the ready-to-use
OracleRepository object in a JNDI directory. At run-time, your application can

Using Oracle XML DB Content Connector 31-7

How to Use Oracle XML DB Content Connector

retrieve the preconfigured OracleRepository object from the JNDI directory. This
approach, recommended by the JCR specification, separates deployment and run-time
concerns.
In Oracle XML DB Content Connector, the set of prefix-to-URI mappings forming the
JCR namespace registry is stored as part of the OracleRepository configuration.
See Also: Oracle Database XML Java API Reference, package
oracle.jcr

Sample Code to Upload File
Example 31–3 is a Java program that uploads a file from the local file system to Oracle
XML DB Repository using Oracle XML DB Content Connector.
Example 31–3

Uploading a File using Oracle XML DB Content Connector

import java.io.FileInputStream;
import javax.jcr.Node;
import javax.jcr.Session;
import javax.jcr.SimpleCredentials;
import oracle.jcr.OracleRepository;
import oracle.jcr.OracleRepositoryFactory;
import oracle.jcr.xdb.XDBRepositoryConfiguration;
import oracle.jdbc.pool.OracleDataSource;
public class UploadFile
{
public static void main(String[] args)
throws Exception
{
String databaseURL = args[0];
String userName = args[1];
String password = args[2];
String parentPath = args[3];
String fileName = args[4];
String mimeType = args[5];
// Get the JCR Repository object.
XDBRepositoryConfiguration configuration =
new XDBRepositoryConfiguration();
OracleDataSource ods =
(OracleDataSource)configuration.getDataSource();
ods.setURL(databaseURL);
OracleRepository repository =
OracleRepositoryFactory.createOracleRepository(configuration);
// Create a JCR Session.
SimpleCredentials sc =
new SimpleCredentials(userName, password.toCharArray());
Session session = repository.login(sc);

31-8 Oracle XML DB Developer's Guide

How to Use Oracle XML DB Content Connector

// Get the parent node.
Node parentNode = (Node)session.getItem(parentPath);
// Get the child contents.
FileInputStream inputStream = new FileInputStream(fileName);
// Create child node.
Node node = parentNode.addNode(fileName, "nt:file");
Node contentNode = node.getNode("jcr:content");
contentNode.setProperty("jcr:mimeType", mimeType);
contentNode.setProperty("jcr:data", inputStream);
// Save changes and logout.
session.save();
session.logout();
}
}
// EOF

You can compile and run Example 31–3 from the command line. The program requires
the following command-line arguments:
■

JDBC database URL

■

User ID

■

User password

■

Folder in Oracle XML DB Repository into which to upload the file

■

File to be uploaded

■

MIME type

Example 31–4 illustrates this.
Example 31–4

Uploading a File Using the Command Line

export CLASSPATH=.:$ORACLE_HOME/lib/jcr-1.0.jar:$ORACLE_HOME/lib/ojcr.jar:$ORACLE_
HOME/lib/xmlparserv2.jar:$ORACLE_HOME/jlib/xquery.jar
javac UploadFile.java
java UploadFile jdbc:oracle:oci:@ quine password /public MyFile.txt text/plain

Additional Code Samples
You can find additional sample code at the following location:
$ORACLE_HOME/xdk/demo/java/jcr

For each code sample, a README file describes its purpose and use.

Logging API for Oracle XML DB Content Connector
Oracle XML DB Content Connector uses the standard java.util.logging
framework. You can use the logging API provided by that framework to control
logging behavior. For example, the following Java code fragment disables all logging.
import java.util.logging.LogManager;
...
LogManager.getLogManager().reset();

Using Oracle XML DB Content Connector 31-9

How to Use Oracle XML DB Content Connector

Supported JCR Compliance Levels
The JSR-170 standard, which defines JCR version 1.0, defines two compliance levels
and a set of optional features. Oracle XML DB Content Connector supports Level 1
(read functions) and Level 2 (write functions).

Oracle XML DB Content Connector Restrictions
This section describes certain restrictions of Oracle XML DB Content Connector.

Default Workspace Name
A single workspace is supported. In calling the login(Credentials, String) or
login(String) methods of javax.jcr.Repository, the workspace name must
be either an empty-string ("") or NULL.

Operations Restricted to Specific Node Types
Methods save() and refresh() of javax.jcr.Item can be called only on nodes
whose type is nt:file or nt:folder. Method move() of javax.jcr.Session
and methods copy() and move() of javax.jcr.Workspace can be called only on
nt:file and nt:folder nodes.

Determining the State of Files or Folders
Methods isNew() and isModified() of javax.jcr.Item return the state of the
file or folder containing the item, not the item itself. Method isNew() returns true if
the file or folder has been created in the JCR transient layer but not saved. Method
isModified() returns true if the file or folder has been changed in the transient
layer but not saved.

Interaction Between Binary and XML Content
The jcr:data property contains the binary-format content of a file. If the file content
is XML, there is also an ojcr:xmlContent node under which its XML content is
exposed as JCR nodes and properties. Changes you make to the ojcr:xmlContent
subtree are not reflected in the jcr:data property until those changes are saved. If
you change both the jcr:data property and the ojcr:xmlContent subtree, then
the ojcr:xmlContent subtree takes precedence when those changes are saved.

Order in Which Changes Are Saved
Method save of class javax.jcr.Session or class javax.jcr.Item saves
changes made in the transient layer. If more than one node or property has been
changed, then JCR does not specify the order in which the changes are stored. Oracle
XML DB Content Connector saves changes in the following:
1.

Apply updates to existing files and folders, in path-sorted order.

2.

Create new files and folders, in path-sorted order.

3.

Move existing files and folders, in reverse path-sorted order.

4.

Delete existing files and folders, in reverse path-sorted order.

Undefined Properties
Properties that have definitions of type UNDEFINED are stored as STRING values.

31-10 Oracle XML DB Developer's Guide

Using XML Schemas with JCR

Node Type nt:base Is Abstract
Node type nt:base is abstract and cannot be specified as the type of a new node.

Node jcr:content Is Created Automatically
When you create a node of type nt:file or nt:folder, a jcr:content node is
created automatically as a child.

Saving Normalizes Node jcr:xmltext
Saving combines successive jcr:xmltext nodes, which represent text within XML
content or user-defined metadata, into a single jcr:xmltext node.

Node Type mix:referenceable
Node types nt:file, nt:folder, and nt:resource are subtypes of mix-in node
type mix:referenceable. Consequently, all nt:file, nt:folder, and
nt:resource nodes can be referenced by UUID. You cannot add
mix:referenceable to nodes of any type.

Full-Text Indexing
You can create a full-text index on file content using PL/SQL package DBMS_XDBT.
This lets queries apply function jcr:contains to property jcr:data of a
jcr:content node. Full-text indexes on other properties are not supported.

Using XML Schemas with JCR
Oracle XML DB Content Connector can create JCR node types from XML schemas.
This section has the following topics:
■

Why Register XML Schemas for Use with JCR?

■

How to Register an XML Schema with JCR

■

How JCR Node Types are Generated from XML Schemas

Why Register XML Schemas for Use with JCR?
XML data can be stored in Oracle XML DB Repository as either file content or
user-defined metadata. In either case, the XML data can be based on an XML schema.
XML schema-based data is validated against an XML schema that has been registered
with Oracle XML DB.
By default, the JCR nodes corresponding to XML document content and user-defined
metadata are of node type nt:unstructured, a generic node type defined by JCR,
even if the XML data is XML schema-based. Oracle XML DB Repository still validates
any changes made through the Oracle XML DB Content Connector against the XML
schema, but it is not possible to access or specify typing metadata through JCR.
However, Oracle XML DB Content Connector lets XML schemas be registered for use
in JCR. This causes the content connector to generate JCR node types for the
XML-schema simple types, complex types, and global element declarations in the
registered XML schema.
In exposing XML data as JCR nodes, the content connector determines whether the
XML data conforms to an XML schema registered for JCR use, based on the value of
XML attribute xsi:schemaLocation or xsi:noNamespaceSchemaLocation of
its root element. If the XML data conforms to a JCR registered XML schema, then the
Using Oracle XML DB Content Connector 31-11

Using XML Schemas with JCR

XML data is exposed as JCR nodes of the node types generated from the XML schema,
instead of using the generic node type nt:unstructured.
You can also use the generated JCR node types to create or update XML document
content and user-defined metadata.
Example 31–5 shows an XML document with XML schema-based content.
Example 31–5

XML Document with XML Schema-Based Content


Alice Smith
123 Maple Street
Mill Valley
CA
90952


The content of Example 31–5 is valid with respect to the XML schema shown in
Example 31–6.
Example 31–6

XML Schema














Initially, this XML schema is not registered for JCR use. The JCR nodes and properties
representing the XML content are shown in Example 31–7.
Example 31–7

JCR Representation of XML Content Not Registered for JCR Use

ojcr:xmlContent (nt:unstructured)
Address (nt:unstructured)
country="US" (String)
name (nt:unstructured)
jcr:xmltext(ojcr:xmltext)
jcr:xmlcharacters="Alice Smith" (String)
street (nt:unstructured)
jcr:xmltext(ojcr:xmltext)
jcr:xmlcharacters="123 Maple Street" (String)
city (nt:unstructured)
jcr:xmltext(ojcr:xmltext)
jcr:xmlcharacters="Mill Valley" (String)
state (nt:unstructured)
jcr:xmltext(ojcr:xmltext)
jcr:xmlcharacters="CA" (String)

31-12 Oracle XML DB Developer's Guide

Using XML Schemas with JCR

zip (nt:unstructured)
jcr:xmltext (ojcr:xmltext)
jcr:xmlcharacters="90952" (String)

The XML schema is then registered for JCR use. The JCR nodes and properties are
shown in Example 31–8.
Example 31–8

JCR Representation of XML Content Registered for JCR Use

ojcr:xmlContent (nt:unstructured)
Address (USAddress)
country="US" (String)
name (xsd:string)
jcr:xmltext(ojcr:xmltext)
jcr:xmlcharacters="Alice Smith" (String)
street (xsd:string)
jcr:xmltext(ojcr:xmltext)
jcr:xmlcharacters="123 Maple Street" (String)
city (xsd:string)
jcr:xmltext(ojcr:xmltext)
jcr:xmlcharacters="Mill Valley" (String)
state (xsd:string)
jcr:xmltext(ojcr:xmltext)
jcr:xmlcharacters="CA" (String)
zip (xsd:long)
jcr:xmltext (ojcr:xmltext)
jcr:xmlcharacters="90952" (Long)

Node Address now has node type USAddress. Similarly, nodes name, street,
city, and state have node type xsd:string. Node zip has node type xsd:long,
and the jcr:xmlcharacters property of its jcr:xmltext child is a LONG property
type.
See Also:

Chapter 29, "User-Defined Repository Metadata"

How to Register an XML Schema with JCR
Before you register an XML schema for use with JCR, you must register it for use with
Oracle XML DB, using PL/SQL procedure DBMS_XMLSCHEMA.registerSchema. For
example, to register an XML schema with location
http://www.example.com/Address, first register it for use with Oracle XML DB,
as shown in Example 31–9. Then, register it for use with JCR, using Oracle XML DB
Content Connector Java APIs, as shown in Example 31–10.
Example 31–9

Registering an XML Schema for Use with Oracle XML DB

BEGIN
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL
=> 'http://www.example.com/Address',
SCHEMADOC
=> bfileContainingSchema,
LOCAL
=> FALSE,
ENABLEHIERARCHY => DBMS_XMLSCHEMA.ENABLE_HIERARCHY_RESMETADATA);
END;
/

Note: You can use only globally registered XML schemas (local =>
false) with JCR.

Using Oracle XML DB Content Connector 31-13

Using XML Schemas with JCR

Example 31–10 Registering an XML Schema for Use with JCR
import oracle.jcr.nodetype.OracleNodeTypeManager;
...
OracleNodeTypeManager ntm = (OracleNodeTypeManager)
session.getWorkspace().getNodeTypeManager();
ntm.registerXMLSchema("http://www.example.com/Address", null);

The list of XML schemas registered for use with JCR is stored in the
OracleRepository object. You can save this registration data by storing the
OracleRepository object in a JNDI directory, as recommended by the JCR
specification.
JCR requires that each node type have a unique name. By default, Oracle XML DB
Content Connector generates JCR nodes types that correspond to a registered XML
schema in the target namespace of the XML schema. If you wish to register two XML
schemas with the same namespace, and the XML schemas declare types with the same
names, you can avoid a name clash by overriding the namespace into which the JCR
node types are generated. Refer to the Javadoc of method registerXMLSchema()
for details.
See Also:
■

■

"Managing XML Schemas with DBMS_XMLSCHEMA" on
page 7-6 for information on registering XML schemas with Oracle
XML DB
Oracle Database XML Java API Reference, package oracle.jcr, for
information on Java method registerXMLSchema()

How JCR Node Types are Generated from XML Schemas
This section describes how Oracle XML DB Content Connector generates JCR node
types from XML schemas that are registered for JCR use.
The type models of JCR and XML Schema are similar but not equivalent. Some aspects
of XML Schema have no representation in JCR. For example, some constraining facets
of an XML-schema simple type are not discoverable through JCR. They are enforced
by Oracle XML DB Content Connector nonetheless.
More generally, the JCR node types generated from an XML schema do not augment,
detract, or alter the XML schema validation performed when XML data that conforms
to that XML schema is created or updated, whether through JCR or other interfaces.

Built-In Simple Types
A JCR node type is provided for each XML Schema built-in type. For example, the JCR
node type xsd:decimal corresponds to the built-in type xsd:decimal.
The inheritance hierarchy of the JCR node types follows that of the built-in types. For
example, xsd:integer is a subtype of xsd:decimal.
Each XML Schema built-in type maps to a JCR property value type, which is used to
represent values of that type in JCR.
Table 31–2

XML Schema Built-In Types Mapped to JCR Property Value Types

XML Schema Built-in Type

JCR Property Value Type

xsd:anySimpleType

STRING

31-14 Oracle XML DB Developer's Guide

Using XML Schemas with JCR

Table 31–2 (Cont.) XML Schema Built-In Types Mapped to JCR Property Value Types
XML Schema Built-in Type

JCR Property Value Type

xsd:anyURI

STRING

xsd:base64Binary

BINARY

xsd:boolean

BOOLEAN

xsd:byte

LONG

xsd:date

DATE (1)

xsd:dateTime

DATE (1)

xsd:decimal

DOUBLE (2)

xsd:double

DOUBLE

xsd:duration

STRING

xsd:ENTITIES

STRING (3)

xsd:ENTITY

STRING

xsd:float

DOUBLE

xsd:gDay

STRING

xsd:gMonth

STRING

xsd:gMonthDay

STRING

xsd:gYear

STRING

xsd:gYearMonth

STRING

xsd:hexBinary

BINARY

xsd:ID

STRING

xsd:IDREF

STRING

xsd:IDREFS

STRING (3)

xsd:int

LONG

xsd:integer

LONG (2)

xsd:language

STRING

xsd:long

LONG

xsd:Name

STRING

xsd:NCName

STRING

xsd:negativeInteger

LONG

xsd:NMTOKEN

STRING

xsd:NMTOKENS

STRING (3)

xsd:nonNegativeInteger

LONG

xsd:nonPositiveInteger

LONG

xsd:normalizedString

STRING

xsd:NOTATION

STRING

xsd:positiveInteger

LONG

xsd:QName

STRING

xsd:short

LONG

Using Oracle XML DB Content Connector 31-15

Using XML Schemas with JCR

Table 31–2 (Cont.) XML Schema Built-In Types Mapped to JCR Property Value Types
XML Schema Built-in Type

JCR Property Value Type

xsd:string

STRING

xsd:time

DATE (1)

xsd:token

STRING

xsd:unsignedByte

LONG

xsd:unsignedInt

LONG

xsd:unsignedLong

LONG

xsd:unsignedShort

LONG

Notes for Table 31–2:
1.

The JCR DATE property type is accessed using java.util.Calendar objects.
Since Calendar requires all fields to be set, a mask of
1970-01-01T00:00:00.000+00:00 is used to supply default values for
missing fields when Property.getDate() or Value.getDate() is called. This
includes omitted hour/minute/second values (for xsd:date), year/month/day
values (for xsd:time), or time-zone values (for xsd:date, xsd:time, and
xsd:dateTime). Calling Property.getString() or Value.getString()
returns the unparsed string representation. Similarly,
Property.setValue(String) or
Property.setValue(valueFactory.createValue(String)) may be used
to set DATE properties without applying the mask.

2.

The value space of xsd:decimal and xsd:integer exceeds that of the
corresponding JCR types, DOUBLE and LONG (accessed as Java double and long
values). Consequently, some xsd:decimal and xsd:integer values can only be
accessed in JCR as strings. For example, bigIntegerProperty.getLong()
throws a javax.jcr.ValueFormatException, but
bigIntegerProperty.getString() returns the unparsed string
representation. Similarly, Property.setValue(String) or
Property.setValue(valueFactory.createValue(String)) may be used
to set DOUBLE or LONG properties to values outside the JCR value space.

3.

xsd:ENTITIES, xsd:IDREFS, and xsd:NMTOKENS are represented in JCR as
multi-valued STRING properties.

XML Schema-Defined Simple Types
A JCR node type is created for each simple type defined in an XML schema. The
inheritance hierarchy of the JCR node types follows that of the XML schema types.
A derived-by-list simple type is represented by a multi-valued JCR property
definition.
A derived-by-union simple type is represented by a JCR property definition with
property type UNDEFINED.
The JCR node type corresponding to an anonymous simple type has a synthetic name
anonymousNodeType#sequenceNumber. Your application should not rely on the
synthesized name. It is not guaranteed to be the same across sessions, and it may
change when an XML schema is registered or deregistered for JCR use or the
definition of a registered XML schema is changed.

31-16 Oracle XML DB Developer's Guide

Using XML Schemas with JCR

Complex Types
A JCR node type is created for each complex type defined in an XML schema. The
inheritance hierarchy of the JCR node types follows that of the XML schema types.
For a JCR node type corresponding to an XML schema complex type:
■

■

■

■

■

A property definition is created for each attribute declaration of the complex type.
Attribute declarations or attribute groups referenced by name in a complex type
are treated as though they were defined in line.
A residual property definition is created if the complex type has an attribute
wildcard.
A child node definition is created for each uniquely-named element declaration in
the complex type's content model. Element declarations or module groups
referenced by name are treated as though they were defined in line. If an element
declaration is the head of a substitution group, a child node definition is also
created for each element declaration within the substitution group.
A residual child node definition is created if the complex type has an element
wildcard.
A jcr:xmltext child node definition is created if the complex type permits XML
text, either because xsd:mixed = "true" or it is an xsd:simpleContent
definition.

The JCR node type for a complex type supports child node ordering.
It is not possible to determine whether a type was derived by extension or restriction
using JCR.
The JCR node type corresponding to an anonymous complex type has a synthetic
name anonymousNodeType#sequenceNumber. Your application should not rely on
the synthesized name. It is not guaranteed to be the same across sessions, and it may
change when an XML schema is registered or deregistered for JCR use or the
definition of a registered XML schema is changed.

Global Element Declarations
A JCR node type is created for each global element declaration in an XML schema. The
local name of the generated node type is formed by prepending an underscore (_) to
the local name of the global element declaration. For example, in a
namespace-qualified purchase order XML schema, a node type named po:_
purchaseOrder is created for global element named po:purchaseOrder.

Using Oracle XML DB Content Connector 31-17

Using XML Schemas with JCR

31-18 Oracle XML DB Developer's Guide

32
Writing Oracle XML DB Applications in Java
This chapter describes how to write Oracle XML DB applications in Java. It includes
design guidelines for writing Java applications including servlets, and how to
configure the Oracle XML DB servlets.
This chapter contains these topics:
■

Overview of Oracle XML DB Java Applications

■

Design Guidelines: Java Inside or Outside the Database?

■

Writing Oracle XML DB HTTP Servlets in Java

■

Configuring Oracle XML DB Servlets

■

HTTP Request Processing for Oracle XML DB Servlets

■

Session Pool and Oracle XML DB Servlets

■

Native XML Stream Support

■

Oracle XML DB Servlet APIs

■

Oracle XML DB Servlet Example

Overview of Oracle XML DB Java Applications
You can use Java code in these ways:
■

In the database using the Java Virtual Machine (VM).

■

In a client or application server, using the OCI driver for JDBC.

Because Java runs in the database in the context of the database server process, the
ways you can deploy and run Java code are restricted to the following:
■

You can run Java code as a stored procedure invoked from SQL or PL/SQL.

■

You can run a Java servlet.

Stored procedures are easier to integrate with SQL and PL/SQL code. They require
Oracle Net Services as the protocol to access Oracle Database.
Servlets work better as the top-level entry point into Oracle Database, and require
using HTTP(S) as the protocol to access Oracle Database.

Which Oracle XML DB APIs Are Available Inside and Outside the Database?
All Oracle XML DB application program interfaces (APIs) are available to applications
running both in the server and outside the database, including:

Writing Oracle XML DB Applications in Java 32-1

Design Guidelines: Java Inside or Outside the Database?

■

JDBC support for XMLType

■

XMLType class

■

Java DOM implementation

Design Guidelines: Java Inside or Outside the Database?
When choosing an architecture for writing Java Oracle XML DB applications, consider
the following guidelines:

HTTP(S): Accessing Java Servlets or Directly Accessing XMLType Resources
If the downstream client wants to deal with XML in its textual representation, then
using HTTP(S) to either access the Java servlets or directly access XMLType resources
performs the best, especially if the XML node tree is not being manipulated much by
the Java program.
The Java implementation in the server can natively move data from the database to the
network without converting character data through UCS-2 Unicode (which is required
by Java strings). In many cases data is copied directly from the database buffer cache
to the HTTP(S) connection. There is no need to convert data from the buffer cache into
the SQL serialization format used by Oracle Net Services, then move it to the JDBC
client, and then convert to XML. Loading on demand and the LRU cache for XMLType
are most effective inside the database server.

Accessing Many XMLType Object Elements: Use JDBC XMLType Support
If the downstream client is an application that programmatically accesses many or
most of the elements of an XMLType instance using Java, then use JDBC XMLType
support for best performance. It is often easier to debug Java programs outside of the
database server, as well.

Use the Servlets to Manipulate and Write Out Data Quickly as XML
Oracle XML DB servlets are intended for writing HTTP stored procedures in Java that
can be accessed using HTTP(S). They are not intended as a platform for developing an
entire Internet application. In that case, the application servlet should be deployed in
Oracle Application Server application server and access data in the database either
using JDBC, or by using the java.net.* or similar APIs to get XML data through
HTTP(S).
They are best used for applications that want to get into the database, manipulate the
data, and write it out quickly as XML, not to format HTML pages for end-users.

Writing Oracle XML DB HTTP Servlets in Java
Oracle XML DB provides a protocol server that supports FTP, HTTP 1.1, WebDAV, and
Java Servlets. Oracle XML DB supports Java Servlet version 2.2, with the following
exceptions:
■

The servlet WAR file (web.xml) is not supported in its entirety. Some web.xml
configuration parameters must be handled manually. For example, creating roles
must be done using the SQL CREATE ROLE command.

■

RequestDispatcher and associated methods are not supported.

■

Method HTTPServletRequest.getCookies() is not supported.

32-2 Oracle XML DB Developer's Guide

Configuring Oracle XML DB Servlets

■
■

Only one ServletContext (and one web-app) is currently supported.
Stateful servlets (and thus the HttpSession class methods) are not supported.
Servlets must maintain state in the database itself.

Configuring Oracle XML DB Servlets
Oracle XML DB servlets are configured using the /xdbconfig.xml file in Oracle
XML DB Repository. Many of the XML elements in this file are the same as those
defined by the Java Servlet 2.2 specification portion of Java 2 Enterprise Edition (J2EE),
and have the same semantics. Table 32–1 lists the XML elements defined for the servlet
deployment descriptor by the Java Servlet specification, along with extension elements
supported by Oracle XML DB.
Table 32–1

XML Elements Defined for Servlet Deployment Descriptors

XML Element Name

Defined By Supported?

Description

Comment

auth-method

Java

no

Specifies an HTTP authentication
method required for access

--

charset

Oracle

yes

Specifies an IANA character set
name

For example: ISO8859,
UTF-8

charset-mapping

Oracle

yes

Specifies a mapping between a
filename extension and a charset

--

context-param

Java

no

Specifies a parameter for a Web
application

Not yet supported

description

Java

yes

A string for describing a servlet or
Web application

Supported for servlets

display-name

Java

yes

A string to display with a servlet or Supported for servlets
Web application

distributable

Java

no

Indicates whether or not this
servlet can function if all instances
are not running in the same Java
virtual machine

All servlets running in
Oracle Database
MUST be
distributable.

errnum

Oracle

yes

Oracle error number

See Oracle Database
Error Messages

error-code

Java

yes

HTTP(S) error code

Defined by RFC 2616

error-page

Java

yes

Defines a URL to redirect to if an
error is encountered.

Can be specified
through an HTTP(S)
error, an uncaught
Java exception, or
through an uncaught
Oracle error message

exception-type

Java

yes

Classname of a Java exception
mapped to an error page

--

extension

Java

yes

A filename extension used to
associate with MIME types,
character sets, and so on.

--

facility

Oracle

yes

Oracle facility code for mapping
error pages

For example: ORA,
PLS, and so on.

form-error-page

Java

no

Error page for form login attempts

Not yet supported

form-login-config

Java

no

Config spec for form-based login

Not yet supported

form-login-page

Java

no

URL for the form-based login page

Not yet supported

Writing Oracle XML DB Applications in Java 32-3

Configuring Oracle XML DB Servlets

Table 32–1 (Cont.) XML Elements Defined for Servlet Deployment Descriptors
XML Element Name

Defined By Supported?

Description

Comment

icon

Java

Yes

URL of icon to associate with a
servlet

Supported for servlets

init-param

Java

Yes

Initialization parameter for a
servlet

--

jsp-file

Java

No

Java Server Page file to use for a
servlet

Not supported

lang

Oracle

Yes

IANA language name

For example: en-US

lang-mapping

Oracle

Yes

Specifies a mapping between a
filename extension and language
content

--

large-icon

Java

Yes

Large sized icon for icon display

--

load-on-startup

Java

Yes

Specifies if a servlet is to be loaded
on startup

--

location

Java

Yes

Specifies the URL for an error page

Can be a local path
name or HTTP(S)
URL

login-config

Java

No

Specifies a method for
authentication

Not yet supported

mime-mapping

Java

Yes

Specifies a mapping between
filename extension and the MIME
type of the content

--

mime-type

Java

Yes

MIME type name for resource
content

For example: text/xml
or
application/octet-stre
am

OracleError

Oracle

Yes

Specifies an Oracle error to
associate with an error page

--

param-name

Java

Yes

Name of a parameter for a Servlet
or ServletContext

Supported for servlets

param-value

Java

Yes

Value of a parameter

--

realm-name

Java

No

HTTP(S) realm used for
authentication

Not yet supported

role-link

Java

Yes

Specifies a role a particular user
must have for accessing a servlet

Refers to a database
role name. Make sure
to capitalize by
default!

role-name

Java

Yes

A servlet name for a role

Just another name to
call the database role.
Used by the Servlet
APIs

security-role

Java

No

Defines a role for a servlet to use

Not supported. You
must manually create
roles using the SQL
CREATE ROLE

security-role-ref

Java

Yes

A reference between a servlet and a -role

servlet

Java

Yes

Configuration information for a
servlet

32-4 Oracle XML DB Developer's Guide

--

Configuring Oracle XML DB Servlets

Table 32–1 (Cont.) XML Elements Defined for Servlet Deployment Descriptors
XML Element Name

Defined By Supported?

Description

Comment

servlet-class

Java

Yes

Specifies the classname for the Java -servlet

servlet-language

Oracle

Yes

Specifies the programming
language in which the servlet is
written.

Either Java, C, or
PL/SQL. Currently,
only Java is supported
for customer-defined
servlets.

servlet-mapping

Java

Yes

Specifies a filename pattern with
which to associate the servlet

All of the mappings
defined by Java are
supported

servlet-name

Java

Yes

String name for a servlet

Used by servlet APIs

servlet-schema

Oracle

Yes

The Oracle Schema in which the
Java class is loaded. If not specified,
then the schema is searched using
the default resolver specification.

If this is not specified,
then the servlet must
be loaded into the SYS
schema to ensure that
everyone can access it,
or the default Java
class resolver must be
altered. Note that the
servlet schema is
capitalized unless the
value is enclosed in
double-quotes.

session-config

Java

No

Configuration information for an
HTTPSession

HTTPSession is not
supported

session-timeout

Java

No

Timeout for an HTTP(S) session

HTTPSession is not
supported

small-icon

Java

Yes

Small icon to associate with a
servlet

--

taglib

Java

No

JSP tag library

JSPs currently not
supported

taglib-uri

Java

No

URI for JSP tag library description
file relative to file web.xml

JSPs currently not
supported

taglib-location

Java

No

Path name relative to the root of the JSPs currently not
supported
Web application where the tag
library is stored

url-pattern

Java

Yes

URL pattern to associate with a
servlet

See Section 10 of Java
Servlet 2.2 spec

web-app

Java

No

Configuration for a Web
application

Only one Web
application is
currently supported

welcome-file

Java

Yes

Specifies a welcome-file name

--

welcome-file-list

Java

Yes

Example:
Defines a list of files to display
when a folder is referenced through index.html
an HTTP GET request

Writing Oracle XML DB Applications in Java 32-5

HTTP Request Processing for Oracle XML DB Servlets

Note:
■

■

The following parameters defined for the web.xml file by Java
are usable only by J2EE-compliant Enterprise Java Bean
containers, and are not required for Java Servlet containers that
do not support a full J2EE environment: env-entry,
env-entry-name, env-entry-value, env-entry-type,
ejb-ref, ejb-ref-type, home, remote, ejb-link,
resource-ref, res-ref-name, res-type, res-auth.
The following elements are used to define access control for
resources: security-constraint,
web-resource-collection, web-resource-name,
http-method, user-data-constraint,
transport-guarantee, auth-constrain. Oracle XML DB
provides this functionality through access control lists (ACLs).
An ACL is a list of access control entries (ACEs) that
determines which principals have access to a given resource or
resources. A future release will support using a web.xml file to
generate ACLs.

See Also: Chapter 34, "Administering Oracle XML DB" for more
information about configuring the /xdbconfig.xml file

HTTP Request Processing for Oracle XML DB Servlets
Oracle XML DB handles an HTTP request using the following steps:
1.

If a connection has not yet been established, then Oracle Listener hands the
connection to a shared server dispatcher.

2.

When a new HTTP request arrives, the dispatcher wakes up a shared server.

3.

The HTTP headers are parsed into appropriate structures.

4.

The shared server attempts to allocate a database session from the Oracle XML DB
session pool, if available, but otherwise creates a new session.

5.

A new database call and a new database transaction are started.

6.

If HTTP(S) has included authentication headers, then the session is authenticated
as that database user (just as if the user logged into SQL*Plus). If no authentication
information is included, and the request is GET or HEAD, then Oracle XML DB
attempts to authenticate the session as the ANONYMOUS user. If that database user
account is locked, then no unauthenticated access is allowed.

7.

The URL in the HTTP request is matched against the servlets in the
xdbconfig.xml file, as specified by the Java Servlet 2.2 specification.

8.

The Oracle XML DB Servlet container is invoked in the Java VM inside Oracle. If
the specified servlet has not been initialized yet, then the servlet is initialized.

9.

The Servlet reads input from the ServletInputStream, and writes output to the
ServletOutputStream, and returns from method service().

10. If no uncaught Oracle error occurred, then the session is put back into the session

pool.
See Also:

32-6 Oracle XML DB Developer's Guide

Chapter 28, "Accessing the Repository using Protocols"

Oracle XML DB Servlet Example

Session Pool and Oracle XML DB Servlets
Oracle Database uses one Java VM for each database session. A session that is reused
from the session pool retains any state that is left over in the Java VM (Java static
variables) from the last time that session was used.
This can be useful in caching Java state that is not user-specific, such as metadata, but
Do not store secure user data in Java static memory. This could turn into a security
hole inadvertently introduced by your application if you are not careful.

Native XML Stream Support
Node class DOM has an Oracle-specific method called write(), which takes the
following arguments, returning void:
■
■

■

java.io.OutputStream stream: A Java stream for writing the XML text.
String charEncoding: The character encoding for writing the XML text. If NULL,
then the database character set is used.
Short indent The number of characters to indent nested XML elements.

Java method write() has a shortcut implementation if the stream provided is the
ServletOutputStream provided inside the database. The contents of the Node are
written in XML in native code directly to the output socket. This bypasses any
conversions into and out of Java objects or Unicode (required for Java strings) and
provides very high performance.

Oracle XML DB Servlet APIs
The APIs supported by Oracle XML DB servlets are defined by the Java Servlet 2.2
specification, the Javadoc for which is available, as of the time of writing this, online
at: http://java.sun.com/products/servlet/2.2/javadoc/index.html
Table 32–2 lists Java Servlet 2.2 methods that are not implemented. They result in
run-time exceptions.
Table 32–2

Java Servlet 2.2 Methods that Are Not Implemented

Interface

Methods Not Implemented

HttpServletRequest

getSession(),
isRequestedSessionIdValid()

HttpSession

all

HttpSessionBindingListener

all

Oracle XML DB Servlet Example
Example 32–1 shows a simple servlet that prints the content of file resource
/public/test/foo1.text.
Example 32–1
import
import
import
import
import
import

An Oracle XML DB Servlet

javax.servlet.http.*;
javax.servlet.*;
java.util.*;
java.io.*;
java.util.*;
java.io.IOException;

Writing Oracle XML DB Applications in Java 32-7

Oracle XML DB Servlet Example

import
import
import
import
import
import
import
import
import
import
import
import

java.io.OutputStreamWriter;
java.io.Reader;
java.io.Writer;
java.sql.DriverManager;
java.sql.SQLException;
oracle.jdbc.OracleConnection;
oracle.jdbc.OracleDriver;
oracle.jdbc.OraclePreparedStatement;
oracle.jdbc.OracleResultSet;
oracle.sql.CLOB;
oracle.xdb.XMLType;
oracle.xdb.spi.XDBResource;

public class test extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException,
IOException {
try {
try {
// Get the database connection for the current HTTP session
DriverManager.registerDriver(new oracle.jdbc.OracleDriver());
OracleDriver ora = new OracleDriver();
OracleConnection databaseConnection =
(OracleConnection) ora.defaultConnection();
String statementText =
"SELECT XDBURIType('/public/test/foo1.txt').getClob() FROM DUAL";
OraclePreparedStatement statement =
(OraclePreparedStatement)
databaseConnection.prepareStatement(statementText);
OracleResultSet resultSet = null;
CLOB content = null;
// Execute the statement
resultSet = (OracleResultSet) statement.executeQuery();
while (resultSet.next())
{// The statement returns a CLOB.
// Copy content of CLOB to server's output stream.
content = resultSet.getCLOB(1);
Reader reader = content.getCharacterStream();
Writer writer =
new OutputStreamWriter(response.getOutputStream());
int bytesSent = 0;
int n;
char[] buffer = new char[CLOB.MAX_CHUNK_SIZE];
while (-1 != (n = reader.read(buffer)))
{ bytesSent = bytesSent + n;
writer.write(buffer, 0, n); }
writer.flush();
if (content.isOpen()) { content.close(); }}
resultSet.close();
statement.close();
databaseConnection.close();
response.getOutputStream().write('\n'); }
catch (SQLException sql)
{ throw new ServletException(sql); }}
catch (ServletException se )
{ se.printStackTrace(); }
finally
{ System.out.flush(); }}}

To install the servlet, you compile it, then load it into Oracle Database:

32-8 Oracle XML DB Developer's Guide

Oracle XML DB Servlet Example

% loadjava –grant public –u quine/curry –r test.class

Finally, register and map the servlet, associating it with a URL, as shown in
Example 32–2.
Example 32–2

Registering and Mapping an Oracle XML DB Servlet

EXEC DBMS_XDB.addServlet('TestServletFoo', 'Java', 'TestServletFoo',
NULL, NULL, 'test', NULL, NULL, 'XDB');
EXEC DBMS_XDB.addServletMapping('/public/test/foo1.txt', 'TestServletFoo');
COMMIT;

Writing Oracle XML DB Applications in Java 32-9

Oracle XML DB Servlet Example

32-10 Oracle XML DB Developer's Guide

33
Using Native Oracle XML DB Web Services
This chapter contains these topics:
■

Overview of Native Oracle XML DB Web Services

■

Configuring and Enabling Web Services for Oracle XML DB

■

Querying Oracle XML DB using a Web Service

■

Accessing PL/SQL Stored Procedures using a Web Service

Overview of Native Oracle XML DB Web Services
Web services provide a standard way for applications to exchange information over
the Internet and access services that implement business logic. Your applications can
access Oracle Database using native Oracle XML DB Web services. One available
service lets you issue SQL and XQuery queries and receive results as XML data.
Another service provides access to all PL/SQL stored functions and procedures.
You can customize the input and output document formats when you use the latter
service. If you do that then the WSDL is automatically generated by the native
database Web services engine.
SOAP 1.1 is the version supported by Oracle XML DB. Applications use HTTP method
POST to submit SOAP requests to native Oracle XML DB Web services. You can
configure the locations of all native Oracle XML DB Web services and WSDL
documents using the Oracle XML DB configuration file, xdbconfig.xml. You can
also configure security settings for the Web services using the same configuration file.
You can use the Accept-Charsets field of the input HTTP header to specify the
character set of Web-service responses. If this header field is omitted, then responses
are in the database character set. The language of the input document and any error
responses is the locale language of the database.
Error handling for native Oracle XML DB Web services uses the SOAP framework for
faults.

Using Native Oracle XML DB Web Services 33-1

Configuring and Enabling Web Services for Oracle XML DB

See Also:
■

■

■

■

■

http://www.w3.org/2002/ws/ for more information on Web
services
The W3C SOAP primer,
http://www.w3.org/TR/2000/NOTE-SOAP-20000508, for
more information on SOAP
http://www.w3.org/TR/wsdl for information on the Web
Services Description Language (WSDL)
http://www.w3.org/TR/2003/REC-soap12-part0-20030624
/#L11549 for information on SOAP fault handling
"Configuring Oracle XML DB using xdbconfig.xml" on page 34-5

Configuring and Enabling Web Services for Oracle XML DB
For security reasons, Oracle XML DB is not preconfigured with the native Web services
enabled. To make native Oracle XML DB Web services available, you must have the
Oracle XML DB HTTP server up and running, and you must explicitly add Web
service configuration. Then, to allow specific users to use Web services, you must grant
them appropriate roles.
1.

Configure Web services – see "Configuring Web Services for Oracle XML DB".

2.

Enable Web services for specific users, by granting them appropriate roles –
"Enabling Web Services for Specific Users".
See Also: "Using HTTP(S) and Oracle XML DB Protocol Server" on
page 28-14 for information about Oracle XML DB HTTP server

Configuring Web Services for Oracle XML DB
To make Web services available for Oracle XML DB, log on as user SYS and add the
servlet configuration that is shown as the query output of Example 33–2 to your Oracle
XML DB configuration file, xdbconfig.xml.
Example 33–1 shows how to use procedures in PL/SQL package DBMS_XDB to add the
servlet. Example 33–2 shows how to verify that the servlet was added correctly.
Example 33–1

Adding a Web Services Configuration Servlet

DECLARE
SERVLET_NAME VARCHAR2(32) := 'orawsv';
BEGIN
DBMS_XDB.deleteServletMapping(SERVLET_NAME);
DBMS_XDB.deleteServlet(SERVLET_NAME);
DBMS_XDB.addServlet(NAME
=> SERVLET_NAME,
LANGUAGE => 'C',
DISPNAME => 'Oracle Query Web Service',
DESCRIPT => 'Servlet for issuing queries as a Web Service',
SCHEMA
=> 'XDB');
DBMS_XDB.addServletSecRole(SERVNAME => SERVLET_NAME,
ROLENAME => 'XDB_WEBSERVICES',
ROLELINK => 'XDB_WEBSERVICES');
DBMS_XDB.addServletMapping(PATTERN => '/orawsv/*',
NAME
=> SERVLET_NAME);
END;
/

33-2 Oracle XML DB Developer's Guide

Querying Oracle XML DB using a Web Service

Example 33–2

Verifying Addition of Web Services Configuration Servlet

XQUERY declare default element namespace "http://xmlns.oracle.com/xdb/xdbconfig.xsd"; (: :)
(: This path is split over two lines for documentation purposes only.
The path should actually be a single long line. :)
for $doc in fn:doc("/xdbconfig.xml")/xdbconfig/sysconfig/protocolconfig/httpconfig/
webappconfig/servletconfig/servlet-list/servlet[servlet-name='orawsv']
return $doc
/
Result Sequence
------------------------------------------------------------------------
orawsv
C
Oracle Query Web Service
Servlet for issuing queries as a Web Service
XDB


XDB_WEBSERVICES
XDB_WEBSERVICES


1 item(s) selected.

See Also: "Configuring Oracle XML DB using xdbconfig.xml" on
page 34-5 for more information about configuring Oracle XML DB
with xdbconfig.xml

Enabling Web Services for Specific Users
To enable Web services for a specific user, log on as user SYS and grant the role XDB_
WEBSERVICES to the user. This role enables Web services over HTTPS. This role is
required to be able to use Web services.
User SYS can, in addition, grant one or both of the following roles to the user:
■

■

XDB_WEBSERVICES_OVER_HTTP – Enable use of Web services over HTTP (not
just HTTPS).
XDB_WEBSERVICES_WITH_PUBLIC – Enable access, using Web services, to
database objects that are accessible to PUBLIC.

If a user is not granted XDB_WEBSERVICES_WITH_PUBLIC, then the user has access,
using Web services, to all database objects (regardless of owner) that would normally
be available to the user, except for PUBLIC objects. To make PUBLIC objects accessible
to a user through Web services, SYS must grant role XDB_WEBSERVICES_WITH_
PUBLIC to the user. With this role, a user can access any PUBLIC objects that would
normally be available to the user if logged on to the database.

Querying Oracle XML DB using a Web Service
The Oracle XML DB Web service for database queries is located at URL
http://host:port/orawsv, where host and port are the host and HTTP(S) port
properties of your database. This Web service has a WSDL document associated with it
that specifies the formats of the incoming and outgoing documents using XML
Schema. This WSDL document is located at URL
http://host:port/orawsv?wsdl.

Using Native Oracle XML DB Web Services 33-3

Querying Oracle XML DB using a Web Service

Your application sends database queries to the Web service as XML documents that
conform to the XML schema listed in Example 33–3.
Example 33–3

XML Schema for Database Queries To Be Processed by Web Service






















































33-4 Oracle XML DB Developer's Guide

Querying Oracle XML DB using a Web Service

This XML schema is contained in the WSDL document. The important parts of
incoming query documents are as follows:
■

query_text – The text of your query. Attribute type specifies the type of your
query: either SQL or XQUERY.

■

bind – A scalar bind-variable value. Attribute name names the variable.

■

bindXML – An XMLType bind-variable value.

■

null_handling – How NULL values returned by the query are to be treated:

■

■

■

■

–

DROP_NULLS – Put nothing in the output (no element). This is the default
behavior.

–

NULL_ATTR – Use an empty element for NULL-value output. Use attribute
xsi:nil = "true" in the element.

–

EMPTY_TAG – Use an empty element for NULL-value output, without a nil
attribute.

max_rows – The maximum number of rows to output for the query. By default, all
rows are returned.
skip_rows – The number of query output rows to skip, before including rows in
the data returned in the SOAP message. You can use this in connection with max_
rows to provide paginated output. The default value is zero (0).
pretty_print – Whether the output document should be formatted for
pretty-printing. The default value is true, meaning that the document is
pretty-printed. When the value is false, no pretty-printing is done, and output
rows are not broken with newline characters.
indentation_width – The number of characters to indent nested elements that
start a new line. The default value is one (1).

■

rowset_tag – Name of the root element of the output document.

■

row_tag – Name of the element whose value is a single row of query output.

■

item_tags_for_coll – Whether to generate collection elements with name
collection_name_item, where collection_name is the name of the
collection.

These elements have the same meanings as corresponding parameters of procedures in
PL/SQL package DBMS_XMLGEN.
Example 33–4 and Example 33–5 show the input and output of a simple SQL query.
Example 33–4

Input XML Document for SQL Query using Query Web Service








8300
false




Using Native Oracle XML DB Web Services 33-5

Accessing PL/SQL Stored Procedures using a Web Service

In Example 33–4, the query text is enclosed in . Although not strictly
necessary in this example, it is appropriate to do this generally, because queries often
contain characters such as < and >. Element bind is used to bind a value (8300) to the
bind variable named e. Element pretty_print turns off pretty-printing of the
output.
Example 33–5

Output XML Document for SQL Query using Query Web Service




206WilliamG
ietzWGIETZ515.123.818107-JUN94AC_ACCOUNT8300205110



Accessing PL/SQL Stored Procedures using a Web Service
The Oracle XML DB Web service for accessing PL/SQL stored functions and
procedures is located at URL
http://host:port/orawsv/dbschema/package/fn_or_proc or, for a function
or procedure that is not in a package (standalone),
http://host:port/orawsv/dbschema/fn_or_proc. Here, host and port are
the host and HTTP(S) port properties of your database, fn_or_proc is the stored
function or procedure name, package is the package it is in, and dbschema is the
database schema owning that package.
The input XML document must contain the inputs needed by the function or
procedure. The output XML document contains the return value and the values of all
OUT variables.
The names of the XML elements in the input and output documents correspond to the
variable names of the function or procedure. The generated WSDL document shows
you the exact XML element names. This is the naming convention used:
■

■

■

■

The XML element introducing the input to a PL/SQL function is named
function-nameInput, where function-name is the name of the function
(uppercase).
The XML elements introducing input parameters for the function are named
param-name-param-type-io-mode, where param-name is the name of the
parameter (uppercase), param-type is its SQL data type, and io-mode is its
input-output mode, as follows:
–

IN – IN mode

–

OUT – OUT mode

–

INOUT – IN OUT mode

The XML element introducing the output from a PL/SQL function is named
Sreturn-type-function-nameOutput, where return-type is the SQL data
type of the return value (uppercase), and function-name is the name of the
function (uppercase).
The XML elements introducing output parameters for the function are named the
same as the output parameters themselves (uppercase). The element introducing
the return value is named RETURN.

33-6 Oracle XML DB Developer's Guide

Accessing PL/SQL Stored Procedures using a Web Service

The return value of a function is in the RETURN element of the output document,
which is always the first element in the document. This return-value position
disambiguates it from any OUT parameter that might be named "RETURN".
Each stored function or procedure is associated with a separate, dynamic Web service
that has its own, generated WSDL document. This WSDL document is located at URL
http://host:port/orawsv/dbschema/package/fn_or_proc?wsdl or
http://host:port/orawsv/dbschema/fn_or_proc?wsdl. In addition, you can
optionally generate a single WSDL document to be used for all stored functions and
procedures in a given package. The URL for that WSDL document is
http://host:port/orawsv/dbschema/package?wsdl.
Data types in the incoming and outgoing XML documents are mapped to SQL data
types for use by the stored function or procedure, according to Table 33–1.
Table 33–1

Web Service Mapping Between XML and SQL Data Types

SQL Data Type

XML Schema
Data Type

CHAR, VARCHAR2, VARCHAR

xsd:string

DATE – Dates must be in the database format.

xsd:date

TIMESTAMP, TIMESTAMP WITH TIMEZONE, TIMESTAMP WITH LOCAL
TIMEZONE

xsd:dateTime

INTERVAL YEAR TO MONTH, INTERVAL DAY TO SECOND

xsd:duration

NUMBER, BINARY_DOUBLE, BINARY_FLOAT

xsd:double

PL/SQL BOOLEAN

xsd:boolean

Object types

complexType

An object type is represented in XML as a complex-type element named the same as
the object type. The object attributes are represented as children of this element.

Example of Using a PL/SQL Function with a Web Service
This section presents a simple PL/SQL function and its access using a Web service.
The function takes as input a department ID and name, and it returns the salary total
of all employees in the department. It also returns, as in-out and output parameters,
respectively, the department name and the number of employees in the department.
The default value of the department ID is 20. In this simple example, the input value
of the in-out parameter dept_name is not actually used. It is ignored, and the correct
name is returned.
Example 33–6 shows the function definition. Example 33–7 shows the WSDL
document that is created automatically from this function definition. Example 33–8
shows an input document that invokes the stored function. Example 33–9 shows the
resulting output document.
Example 33–6

Definition of PL/SQL Function Used for Web-Service Access

CREATE OR REPLACE PACKAGE salary_calculator AUTHID CURRENT_USER AS
FUNCTION TotalDepartmentSalary (dept_id
IN
NUMBER DEFAULT 20,
dept_name IN OUT VARCHAR2,
nummembers OUT
NUMBER)
RETURN NUMBER;
END salary_calculator;
/

Using Native Oracle XML DB Web Services 33-7

Accessing PL/SQL Stored Procedures using a Web Service

CREATE OR REPLACE PACKAGE BODY salary_calculator AS
FUNCTION TotalDepartmentSalary (dept_id
IN
NUMBER DEFAULT 20,
dept_name IN OUT VARCHAR2,
nummembers OUT
NUMBER)
RETURN NUMBER IS
sum_sal NUMBER;
BEGIN
SELECT SUM(salary) INTO sum_sal FROM employees
WHERE department_id = dept_id;
SELECT department_name INTO dept_name FROM departments
WHERE department_name = dept_name;
SELECT count(*) INTO nummembers FROM employees
WHERE department_id = dept_id;
RETURN sum_sal;
END;
END;
/
Example 33–7

WSDL Document Corresponding to a Stored PL/SQL Function




































33-8 Oracle XML DB Developer's Guide

Accessing PL/SQL Stored Procedures using a Web Service

















Oracle Web Service





Example 33–8

Input XML Document for PL/SQL Query using Web Service


30Purchasing

Example 33–9

Output XML Document for PL/SQL Query using Web Service





24900
6
Purchasing




Using Native Oracle XML DB Web Services 33-9

Accessing PL/SQL Stored Procedures using a Web Service

33-10 Oracle XML DB Developer's Guide

Part VI
Oracle Tools that Support Oracle XML DB
Part VI of this manual provides information about Oracle tools that you can use with
Oracle XML DB. It describes tools for managing Oracle XML DB, loading XML data,
and exchanging XML data.
Part VI contains the following chapters:
■

Chapter 34, "Administering Oracle XML DB"

■

Chapter 35, "Loading XML Data using SQL*Loader"

■

Chapter 36, "Exporting and Importing XMLType Tables"

■

Chapter 37, "Exchanging XML Data using Oracle Streams AQ"

34
Administering Oracle XML DB
This chapter describes how to administer Oracle XML DB. It includes information
about installing, upgrading, and configuring Oracle XML DB.
This chapter contains these topics:
■

Installing Oracle XML DB

■

Upgrading an Existing Oracle XML DB Installation

■

Administering Oracle XML DB using Oracle Enterprise Manager

■

Configuring Oracle XML DB using xdbconfig.xml
See Also: "Configuring Resources for XLink and XInclude" on
page 23-9 for information on configuring Oracle XML DB Repository
resources for use with XLink and XInclude

Installing Oracle XML DB
You can perform a new installation of Oracle XML DB with or without Database
Configuration Assistant (DBCA). You are required to install Oracle XML DB manually
without DBCA if you upgrade an existing installation.
Do not uninstall Oracle XML DB in a database that contains
any XMLType data without first contacting Oracle Support.

Caution:

Installing Oracle XML DB with Database Configuration Assistant
Oracle XML DB is part of the seed database and is installed by Database Configuration
Assistant (DBCA) by default. No additional steps are required to install Oracle
XML DB.
However, if you select the advanced database configuration, then you can configure
the SYSAUX tablespace, which is used for Oracle XML DB Repository, and the port
numbers for protocols FTP, HTTP(S), and WebDAV.
By default, DBCA performs the following tasks during installation:
■

Creates tablespace SYSAUX for Oracle XML DB Repository

■

Enables all protocol access

Tablespace SYSAUX holds the data stored in Oracle XML DB Repository, including
data stored using:
■

SQL, for example using RESOURCE_VIEW and PATH_VIEW

Administering Oracle XML DB 34-1

Installing Oracle XML DB

■

Protocols such as FTP, HTTP(S), and WebDAV

You can store data in tables outside of this tablespace and access the data through
Oracle XML DB Repository, by having REFs to that data stored in the tables in this
tablespace.
See Also: "Anonymous Access to Oracle XML DB Repository using
HTTP" on page 28-17 for information about allowing unauthenticated
access to the repository

Dynamic Protocol Registration of FTP and HTTP(S) Services with Local Listener
Oracle XML DB installation dynamically registers FTP and HTTP(S) services with the
local listener. You can perform start, stop, and query with lsnrctl. For example:
■

start: lsnrctl start

■

stop: lsnrctl stop

■

query: lsnrctl status

Changing FTP or HTTP(S) Port Numbers To change FTP and HTTP(S) port numbers,
update elements , , and  in file
/xdbconfig.xml in Oracle XML DB Repository.
After updating the port numbers, dynamic protocol registration automatically stops
FTP/HTTP(S) service on old port numbers and starts them on new port numbers if the
local listener is up. If the local listener is not up, restart the listener after updating the
port numbers.
See Also: Chapter 28, "Accessing the Repository using Protocols"
for information about configuring protocols

Post-installation Oracle XML DB uses dynamic protocol registration to set up FTP and
HTTP listener services with the local listener. Ensure that the listener is up when you
access Oracle XML DB protocols.
If the listener is running on a port that is not standard (for
example, not 1521), then, in order for the protocols to register with the
correct listener, the init.ora file must contain a local_listener
entry. This references a TNSNAME entry that points to the correct
listener. After editing the init.ora parameter, you must regenerate
the SPFILE entry using CREATE SPFILE.

Note:

Installing Oracle XML DB Manually without DBCA
You can install Oracle XML DB manually, by running the catqm SQL script in
directory rdbms/admin as database user SYS. Before running the script, you must
install the database. If you expect Oracle XML DB Repository to contain a large
amount of data, then you might also want to create a separate tablespace for Oracle
XML DB.
Here is the syntax for catqm, where:
■

xdb_password is the password

■

xdb_ts_name is the tablespace to use for Oracle XML DB

■

temp_ts_name is the temporary tablespace

34-2 Oracle XML DB Developer's Guide

Upgrading an Existing Oracle XML DB Installation

■

secure_file_for_repo is YES or NO (uppercase), YES meaning to use
SecureFile LOB storage for Oracle XML DB Repository

catqm.sql xdb_password xdb_ts_name temp_ts_name secure_file_for_repos

For example:
catqm.sql change_on_install SYSAUX TEMP YES

Note:
■

■

SecureFile LOB storage can be created only in a tablespace that
uses automatic segment space management. See Oracle Database
Administrator's Guide.
Database compatibility must be 11.0.0.0 or greater, in order to use
SecureFile LOB storage.

Post-Installation
After the manual installation, carry out these tasks:
1.

Add the following dispatcher entry to the init.ora file:
dispatchers="(PROTOCOL=TCP) (SERVICE=XDB)"

2.

Restart the database and the listener to enable Oracle XML DB protocol access.
See Also: "Anonymous Access to Oracle XML DB Repository using
HTTP" on page 28-17 for information about allowing unauthenticated
access to the repository

Upgrading an Existing Oracle XML DB Installation
The following considerations apply to all upgrades to Oracle Database 11g:
■
■

■

Run script catproc.sql, as always.
As a post-upgrade step, if you want Oracle XML DB functionality, then you must
install Oracle XML DB manually as described in "Installing Oracle XML DB
Manually without DBCA" on page 34-2.
ACL security: In releases prior to Oracle Database 11g Release 1, conflicts among
ACEs for the same principal and same privilege were resolved by giving priority
to any ACE that had child deny, whether or not preceding ACEs had child grant,
that is, ACE order did not matter. In Oracle Database 11g this
deny-trumps-grant behavior is still available, but it is not the default behavior.
"ACL and ACE Evaluation" on page 27-8 for information
about conflicts among ACEs

See Also:

Validation of ACL Documents and Configuration File
Access control list (ACL) documents are stored in table XDB$ACL. The Oracle XML DB
configuration file, xdbconfig.xml, is stored in table XDB$CONFIG. Starting with
Oracle Database 11g Release 1, these tables use the post-parse (binary XML) storage
model. This implies that ACL documents and the configuration file are fully validated
against their respective XML schemas. Validation takes place during upgrade, using

Administering Oracle XML DB 34-3

Administering Oracle XML DB using Oracle Enterprise Manager

your existing ACL documents and configuration file and the corresponding existing
XML schemas.
If an ACL document fails to validate during upgrade, then the document is moved to
table XDB$INVALID_ACL.
If validation of configuration file xdbconfig.xml fails during upgrade, then the file
is saved in table XDB$INVALID_CONFIG, the default configuration file replaces it in
table XDB$CONFIG, and the XDB component of the database is marked invalid. You
must then start the database in normal mode and fix the XDB component, before trying
to use the database.
To fix the XDB component, you can fix the invalid files to make them valid, and then
call PL/SQL procedure RecoverUpgrade. After validating, this procedure moves the
fixed files to tables XDB$ACL and XDB$CONFIG, and marks the XDB component valid.
As an option, you can call procedure RecoverUpgrade with parameter use_
default set to TRUE, to abandon any invalid files. In this case, any valid files are
moved to tables XDB$ACL and XDB$CONFIG, and any remaining invalid files are
deleted. Default files are used in place of any invalid files. For ACLs, the default ACL
document is used. For the configuration file, the default xdbconfig.xml is used (in
which ACE order matters).

Caution: Use a TRUE value for parameter use_default only if you
are certain that you no longer need the old ACL files or configuration
file that are invalid. These files are deleted.

Administering Oracle XML DB using Oracle Enterprise Manager
Oracle Enterprise Manager is a graphical tool supplied with Oracle Database that lets
you perform database administration tasks easily. You can use it to perform the
following tasks related to Oracle XML DB:
■

Configure Oracle XML DB. View or edit parameters for the Oracle XML DB
configuration file, /xdbconfig.xml.
For information about configuring Oracle XML DB without using Oracle
Enterprise Manager, see "Configuring Oracle XML DB using xdbconfig.xml" on
page 34-5.

■

Search, create, edit, undelete Oracle XML DB Repository resources and their
associated access control lists (ACLs).
For information about creating and managing resources without using Oracle
Enterprise Manager, see Part V, "Oracle XML DB Repository".

■

Search, create, edit, and delete XMLType tables and views.

■

Search, create, register, and delete XML schemas.
For information about manipulating XML schemas without using Oracle
Enterprise Manager, see Chapter 7, "XML Schema Storage and Query: Basic".

■

Create function-based indexes based on XPath expressions.
For information about creating function-based indexes without using Oracle
Enterprise Manager, see Chapter 6, "Indexing XMLType Data".

34-4 Oracle XML DB Developer's Guide

Configuring Oracle XML DB using xdbconfig.xml

See Also: The online help available with Oracle Enterprise Manager,
for information about using Enterprise Manager to perform these
tasks

Configuring Oracle XML DB using xdbconfig.xml
Oracle XML DB is managed internally through a configuration file,
/xdbconfig.xml, which is stored as a resource in Oracle XML DB Repository. As an
alternative to using Oracle Enterprise Manager to configure Oracle XML DB, you can
configure it directly using the Oracle XML DB configuration file.
The configuration file can be modified at run time. Updating the configuration file
creates a new version of this repository resource. At the start of each session, the
current version of the configuration file is bound to that session. The session uses this
configuration-file version for its duration, unless you make an explicit call to refresh
the session to the latest version.

Oracle XML DB Configuration File, xdbconfig.xml
The configuration of Oracle XML DB is defined and stored in an Oracle XML DB
Repository resource, /xdbconfig.xml, which conforms to the Oracle XML DB
configuration XML schema: http://xmlns.oracle.com/xdb/xdbconfig.xsd.
To configure or reconfigure Oracle XML DB, update file /xdbconfig.xml. Its
structure is described in the following sections. You need administrator privileges to
access file /xdbconfig.xml.
See Also: "xdbconfig.xsd: XML Schema for Configuring Oracle
XML DB" on page A-16 for a complete listing of the Oracle XML DB
configuration XML schema

 (Top-Level Element)
Element  is the top-level element. Its structure is as follows:

 ... 
 ... 


Element  defines system-specific, built-in parameters. Element
 lets you store new custom parameters.

 (Child of )
Element  is a child of . Its structure is as follows:

general parameters
 ... 


Element  includes as content several general parameters that apply to
all of Oracle XML DB, such as the maximum age of an access control list (ACL) and
whether or not Oracle XML DB is case sensitive. Child  contains
protocol-specific parameters.

Administering Oracle XML DB 34-5

Configuring Oracle XML DB using xdbconfig.xml

 (Child of )
Element  is a child of . It contains any parameters that
you may want to add.

 (Child of )
Element  is a child of . Its structure is as follows:

 ... 
 ... 
 ... 


Under , Oracle Database stores parameters that apply to all protocols, such
as MIME-type information. Parameters that are specific to protocols FTP and HTTP(S)
are in elements  and , respectively.
See Also: Chapter 28, "Accessing the Repository using Protocols",
Table 28–1, Table 28–2, and Table 28–3, for a list of protocol
configuration parameters

 (Child of )
Element  is a child of . Its structure is as follows:

...

...

...

 ... 
...



...
 ... 


Element  has the following child elements, in addition to others:
■

 – used to configure Web-based applications. This includes Web
application-specific parameters, such as icon name, display name for the
application, and a list of servlets.
Element  is a child of  that is used to define
servlets. It has child , which has child  (see
" (Descendant of )" on page 34-7).

■

1

1 – used to define global configuration parameters when configuring the
embedded PL/SQL gateway. Each global parameter is defined with a child element of
. The element name is the same as the global parameter name. The
element content is the same as the parameter value.

There are two different  elements that are used to configure the embedded PL/SQL
gateway. One, a child of , defines global parameters. The other, a child of
, defines DAD attributes.

34-6 Oracle XML DB Developer's Guide

Configuring Oracle XML DB using xdbconfig.xml

The recommended way to configure the embedded PL/SQL gateway is to use the
procedures in PL/SQL package DBMS_EPG, not to edit file xdbconfig.xml.
See Also:
■

■

■

■

Chapter 28, "Accessing the Repository using Protocols",
Table 28–1, Table 28–2, and Table 28–3, for a list of protocol
configuration parameters
Oracle Database Advanced Application Developer's Guide, for
complete information on configuring and using the embedded
PL/SQL gateway
Oracle Fusion Middleware Administrator's Guide for Oracle HTTP
Server for information about mod_plsql and conceptual
information about using the PL/SQL gateway
Oracle Database PL/SQL Packages and Types Reference, for
information about package DBMS_EPG

 (Descendant of )
An optional  element, child of , configures the embedded
PL/SQL gateway servlet. However, the recommended way to configure the embedded
gateway is to use the procedures in PL/SQL package DBMS_EPG, not to edit file
xdbconfig.xml.
Element  has a child element for each embedded PL/SQL DAD attribute2
that is needed to configure the embedded gateway. All such children are optional. The
element name is the same as the DAD attribute name. The element content is the same
as the DAD-attribute value.
Element  is a descendent of  – see " (Child of
)" on page 34-6. It is used to configure servlets, including Java
servlets and embedded PL/SQL gateway servlets.
See Also:
■

■

■

■

Chapter 32, "Writing Oracle XML DB Applications in Java" for
information about configuring Java servlets
Oracle Database Advanced Application Developer's Guide, for
complete information on configuring and using the embedded
PL/SQL gateway
Oracle Application Express Application Builder User's Guide, for
information about Oracle Application Express
Oracle Database PL/SQL Packages and Types Reference, for
information about package DBMS_EPG

Oracle XML DB Configuration File Example
The following is a sample Oracle XML DB configuration file:
Example 34–1

Oracle XML DB Configuration File



900
32
,
true
300
65536
100
false
3600
/sys/log/xdblog.xml
0
1048576





au
audio/basic


avi
video/x-msvideo


bin
application/octet-stream




en
english






gzip
zip file


tar
tar file



50
6000


34-8 Oracle XML DB Developer's Guide

Configuring Oracle XML DB using xdbconfig.xml


2100
local_listener
tcp
/sys/log/ftplog.xml
0
6000
8192


8080
local_listener
tcp
64
6000
XDB HTTP Server
16384
2000000000
/sys/log/httplog.xml
0
Basic realm="XDB"


index.html
index.htm






/oradb/*
DBURIServlet




DBURIServlet
DBURI
C
Servlet for accessing DBURIs

authenticatedUser
authenticatedUser







1024
16



Administering Oracle XML DB 34-9

Configuring Oracle XML DB using xdbconfig.xml

Oracle XML DB Configuration API
You can access the Oracle XML DB configuration file, xdbconfig.xml, the same way
you access any other XML schema-based resource in the hierarchy. It can be accessed
using FTP, HTTP(S), WebDAV, Oracle Enterprise Manager, or any of the resource and
Document Object Model (DOM) APIs for Java, PL/SQL, or C (OCI).
For convenience, you can use PL/SQL package DBMS_XDB package for configuration
access. It exposes the following functions and procedures:
■
■

■

cfg_get – Returns the configuration information for the current session.
cfg_refresh – Refreshes the session configuration information using the current
configuration file. Typical uses of cfg_refresh include the following:
–

You have modified the configuration and now want the session to pick up the
latest version of the configuration information.

–

It has been a long running session, the configuration has been modified by a
concurrent session, and you want the current session to pick up the latest
version of the configuration information.

cfg_update – Updates the configuration information, writing the configuration
file. A COMMIT is performed.

Example 34–2 updates parameters ftp-port and http-port in the configuration
file.
Example 34–2

Updating the Configuration File using CFG_UPDATE and CFG_GET

DECLARE
v_cfg XMLType;
BEGIN
SELECT updateXML(DBMS_XDB.cfg_get(),
'/xdbconfig/descendant::ftp-port/text()',
'2121',
'/xdbconfig/descendant::http-port/text()',
'19090')
INTO v_cfg FROM DUAL;
DBMS_XDB.cfg_update(v_cfg);
COMMIT;
END;
/

If you have many parameters to update, then it can be easier to use FTP, HTTP(S), or
Oracle Enterprise Manager to update the configuration.
See Also:

Oracle Database PL/SQL Packages and Types Reference

Configuring Default Namespace to Schema Location Mappings
Oracle XML DB identifies schema-based XMLType instances by pre-parsing the input
XML document. If the appropriate xsi:schemaLocation or
xsi:noNamespaceSchemaLocation attribute is found, then the specified schema
location URL is used to consult the registered schema. If the appropriate xsi:
attribute is not found, the XML document is considered to be non-schema-based.
Oracle XML DB provides a mechanism to configure default schema location
mappings. If the appropriate xsi: attribute is not specified in the XML document, the
default schema location mappings is used. Element schemaLocation-mappings of
the Oracle XML DB configuration XML schema, xdbconfig.xsd, can be used to
specify the mapping between (namespace, element) pairs and the default schema

34-10 Oracle XML DB Developer's Guide

Configuring Oracle XML DB using xdbconfig.xml

location. If the element value is empty, the mapping applies to all global elements in
the specified namespace. If the namespace value is empty, it corresponds to the null
namespace.
The definition of the schemaLocation-mappings element is as follows:











The schema location used depends on mappings in the Oracle XML DB configuration
file for the namespace used and the root document element. For example, assume that
the document does not have the appropriate xsi: attribute to indicate the schema
location. Consider a document root element R in namespace N. The algorithm for
identifying the default schema location is as follows:
1.

If the Oracle XML DB configuration file has a mapping for N and R, the
corresponding schema location is used.

2.

If the configuration file has a mapping for N, but not R, the schema location for N
is used.

3.

If the document root R does not have any namespace, the schema location for R is
used.

For example, suppose that your Oracle XML DB configuration file includes the
following mapping:


http://www.oracle.com/example
root
http://www.oracle.com/example/sch.xsd


http://www.oracle.com/example2

http://www.oracle.com/example2/sch.xsd



specialRoot
http://www.oracle.com/example3/sch.xsd



The following schema locations are used:
■

Root element = root
–

Namespace = http://www.oracle.com/example

–

Schema URL = http://www.oracle.com/example/sch.xsd
Administering Oracle XML DB

34-11

Configuring Oracle XML DB using xdbconfig.xml

This mapping is used when the instance document specifies:

■

Root element = null (any global element in the namespace)
–

Namespace = http://www.oracle.com/example2

–

Schema URL = http://www.oracle.com/example2/sch.xsd

This mapping is used when the instance document specifies:

■

Root element = specialRoot
–

Namespace = null (i.e null namespace)

–

Schema URL = http://www.oracle.com/example3/sch.xsd

This mapping is used when the instance document specifies:


This functionality is available only on the server side, that
is, when XML is parsed on the server. If XML is parsed on the client
side, the appropriate xsi: attribute is still required.

Note:

Configuring XML File Extensions
Oracle XML DB Repository treats certain files as XML documents, based on their file
extensions. When such files are inserted into the repository, Oracle XML DB pre-parses
them to identify the schema location (or uses the default mapping if present) and
inserts the document into the appropriate default table.
By default, the following extensions are considered as XML file extensions: xml, xsd,
xsl, xlt. In addition, Oracle XML DB provides a mechanism for applications to
specify other file extensions as XML file extensions. The xml-extensions element is
defined in the configuration schema,
http://xmlns.oracle.com/xdb/xdbconfig.xsd, as follows:







For example, the following fragment from the Oracle XML DB configuration file,
xdbconfig.xml, specifies that files with extensions vsd, vml, and svgl should be
treated as XML files:

vsd
vml
svgl


34-12 Oracle XML DB Developer's Guide

Package DBMS_XDB_ADMIN

Package DBMS_XDB_ADMIN
Table 34–1 describes DBMS_XDB_ADMIN PL/SQL procedures for managing and
configuring Oracle XML DB and Oracle XML DB Repository.
Table 34–1

DBMS_XDB_ADMIN Management Procedures

Function/Procedure

Description

moveXDB_tablespace

Move database schema XDB to the specified tablespace.

rebuildHierarchicalIndex Rebuild the hierarchical repository index. This can be needed from time to time,
in particular after invoking moveXDB_tablespace.

In a default, general-purpose database, where database
schema XDB is in tablespace SYSAUX, you must use DBMS_XDB_
ADMIN.moveXDB_tablespace before performing a full database
export. A full database export does not export data from tablespaces
SYSTEM or SYSAUX.

Note:

Prior to Oracle Database 11g Release 2 (11.2.0.3), these
procedures belonged to PL/SQL package DBMS_XDB. These two
procedures in package DBMS_XDB are deprecated as of release 11.2.0.3.

Note:

See Also:

Oracle Database PL/SQL Packages and Types Reference

Administering Oracle XML DB

34-13

Package DBMS_XDB_ADMIN

34-14 Oracle XML DB Developer's Guide

35
Loading XML Data using SQL*Loader
This chapter describes how to load XML data into Oracle XML DB with a focus on
SQL*Loader.
This chapter contains these topics:
■

Overview of Loading XMLType Data Into Oracle Database

■

Loading XMLType Data using SQL*Loader

■

Loading Large XML Documents into Oracle Database
See Also:

Chapter 3, "Using Oracle XML DB"

Overview of Loading XMLType Data Into Oracle Database
Starting with Oracle9i release 1 (9.0.1), the Export-Import utility and SQL*Loader
support XMLType as a column type. Starting with Oracle Database 10g, SQL*Loader
also supports loading XMLType tables. You can load XMLType data with SQL*Loader
using either the conventional method or the direct-path method, regardless of how it is
stored (structured, unstructured, or binary XML storage).

For structured storage of XML data, if the data involves
inheritance (extension or restriction) of XML Schema types, then
SQL*Loader does not support direct-path loading.

Note:

That is, if an XML schema contains a complexType element that
extends or restricts another complexType element (the base type),
then this results in some SQL types being defined in terms of other
SQL types. In this case, direct-path loading is not supported for
object-relational storage.
See Also: Chapter 36, "Exporting and Importing XMLType
Tables" and Oracle Database Utilities

Oracle XML DB Repository information is not exported when user data is exported.
Neither the resources nor any information are exported.

Loading XMLType Data using SQL*Loader
XML columns are columns declared to be of type XMLType.

Loading XML Data using SQL*Loader 35-1

Loading XMLType Data using SQL*Loader

SQL*Loader treats XMLType columns and tables like object-relational columns and
tables. All methods described in the following sections for loading LOB data from the
primary datafile or from a LOBFILE value apply also to loading XMLType columns
and tables when the XMLType data is stored as a LOB.
See Also:

Oracle Database Utilities

You cannot specify a SQL string for LOB fields. This is true
even if you specify LOBFILE_spec.

Note:

XMLType data can be present in a control file or in a LOB file. In the former case, the
LOB file name is present in the control file.
Because XMLType data can be quite large, SQL*Loader can load LOB data from either
a primary datafile (in line with the rest of the data) or from LOB files, independent of
how the data is stored (the underlying storage can, for example, still be
object-relational).

Loading XMLType Data in LOBs using SQL*Loader
To load internal LOBs, Binary Large Objects (BLOBs), Character Large Objects
(CLOBs), and National Character Large Object (NCLOBs), or XMLType columns and
tables from a primary datafile, use the following standard SQL*Loader formats:
■

Predetermined size fields

■

Delimited fields

■

Length-value pair fields

These formats are described in the following sections and in more detail in Oracle
Database Utilities.

Loading LOB Data in Predetermined Size Fields
This is a very fast and conceptually simple format to load LOBs.
Because the LOBs you are loading might not be of equal size,
you can use whitespace to pad the LOB data to make the LOBs all of
equal length within a particular data field.

Note:

Loading LOB Data in Delimited Fields
This format handles LOBs of different sizes within the same column (datafile field)
without problem. However, this added flexibility can affect performance, because
SQL*Loader must scan through the data, looking for the delimiter string.
As with single-character delimiters, when you specify string delimiters, you should
consider the character set of the datafile. When the character set of the datafile is
different than that of the control file, you can specify the delimiters in hexadecimal
(that is, hexadecimal string). If the delimiters are specified in hexadecimal notation,
then the specification must consist of characters that are valid in the character set of
the input datafile. In contrast, if hexadecimal specification is not used, then the
delimiter specification is considered to be in the client (that is, the control file)
character set. In this case, the delimiter is converted into the datafile character set
before SQL*Loader searches for the delimiter in the datafile.

35-2 Oracle XML DB Developer's Guide

Loading Large XML Documents into Oracle Database

Loading XML Columns Containing LOB Data from LOBFILEs
LOB data can be lengthy enough so that it makes sense to load it from a LOBFILE
instead of from a primary datafile. In LOBFILEs, LOB data instances are still
considered to be in fields (predetermined size, delimited, length-value), but these
fields are not organized into records (the concept of a record does not exist within
LOBFILEs). Therefore, the processing overhead of dealing with records is avoided.
This type of organization of data is ideal for LOB loading.
There is no requirement that a LOB from a LOBFILE fit in memory. SQL*Loader reads
LOBFILEs in 64 KB chunks.
In LOBFILEs the data can be in any of the following types of fields, any of which can
be used to load XML columns:
■

A single LOB field into which the entire contents of a file can be read

■

Predetermined size fields (fixed-length fields)

■

Delimited fields (that is, TERMINATED BY or ENCLOSED BY)
The clause PRESERVE BLANKS is not applicable to fields read from a LOBFILE.

■

Length-value pair fields (variable-length fields).
To load data from this type of field, use the VARRAY, VARCHAR, or VARCHAR2
SQL*Loader data types.

Specifying LOBFILEs
You can specify LOBFILEs either statically (you specify the name of the file) or
dynamically (you use a FILLER field as the source of the filename). In either case,
when the EOF of a LOBFILE is reached, the file is closed and additional attempts to
read data from that file produce results equivalent to reading data from an empty
field.
You should not specify the same LOBFILE as the source of two different fields. If you
do so, then typically, the two fields read the data independently.

Loading XMLType Data Directly from a Control File using SQL*Loader
XMLType data can be loaded directly from a control file. SQL*Loader treats XMLType
data like any scalar type. For example, consider a table containing a NUMBER column
followed by an XMLType column that is stored object-relationally. The control file used
for this table can contain the value of the NUMBER column followed by the value of the
XMLType instance.
SQL*Loader accommodates XMLType instances that are very large. You also have the
option to load such data from a LOB file.

Loading Large XML Documents into Oracle Database
You can use SQL*Loader to load large amounts of XML data into Oracle Database.
Follow these steps:
1.

List in a data file, say filelist.dat, the locations of the XML documents to be
loaded.

2.

Create a control file, say load_data.ctl, with commands that process the files
listed in the data file.

3.

Invoke the SQL*Loader shell command, sqlldr, passing it the name of the
control file.
Loading XML Data using SQL*Loader 35-3

Loading Large XML Documents into Oracle Database

This is illustrated in Example 35–2, Example 35–1, and Example 35–3. File
filelist.dat lists XML files that contain purchase orders for the year 2002.
Example 35–1

Data File filelist.dat: List of XML Files to Load

2002/Jan/AMCEWEN-20021009123335370PDT.xm
2002/Jan/AWALSH-2002100912333570PDT.xml
2002/Jan/CJOHNSON-20021009123335170PDT.xml
2002/Jan/LSMITH-20021009123335500PDT.xml
2002/Jan/PTUCKER-20021009123335430PDT.xml
2002/Jan/SBELL-20021009123335280PDT.xml
2002/Jan/SKING-20021009123335560PDT.xml
2002/Jan/SMCCAIN-20021009123335470PDT.xml
2002/Jan/TFOX-20021009123335520PDT.xml
2002/Jan/VJONES-20021009123335350PDT.xml
2002/Jan/WSMITH-20021009123335450PDT.xml
2002/Feb/AMCEWEN-20021009123335600PDT.xml
2002/Feb/AMCEWEN-20021009123335701PDT.xml
2002/Feb/DAUSTIN-20021009123335811PDT.xml
2002/Feb/EABEL-20021009123335791PDT.xml
2002/Feb/PTUCKER-20021009123335721PDT.xml
2002/Feb/PTUCKER-20021009123335821PDT.xml
2002/Feb/SBELL-20021009123335771PDT.xml
2002/Feb/SMCCAIN-20021009123335681PDT.xml
2002/Feb/WSMITH-20021009123335650PDT.xml
2002/Feb/WSMITH-20021009123335741PDT.xml
2002/Feb/WSMITH-20021009123335751PDT.xml
...
Example 35–2

Control File load_datra.ctl, for Loading Purchase-Order XML Documents

load data
infile 'filelist.dat'
append
into table PURCHASEORDER
xmltype(XMLDATA)
(
filename filler char(120),
XMLDATA lobfile(filename) terminated by eof
)
Example 35–3

Loading XML Data Using Shell Command sqlldr

sqlldr load_data.ctl

For direct-path loading, use this instead:
sqlldr load_data.ctl direct=y

See Also:
■

■

Chapter 3, "Using Oracle XML DB", "Loading Large XML Files
using SQL*Loader" on page 3-9
Oracle Database Utilities for information about shell command
sqlldr

35-4 Oracle XML DB Developer's Guide

36
Exporting and Importing XMLType Tables
This chapter describes how you can export and import XMLType tables for use with
Oracle XML DB using Oracle Data Pump.
The original Export and Import utilities can be used to migrate
data to database releases that are prior to Oracle Database 11g Release
2 (11.2).

Note:

This chapter discusses the following topics:
■

Overview of Oracle Data Pump

■

EXPORT/IMPORT Support in Oracle XML DB

■

Exporting XML Schema-Based XMLType Tables

■

Exporting Hierarchy-Enabled (Repository) Tables

■

Exporting and Importing Transportable Tablespaces

■

Repository Resources and Foldering Support

■

Export/Import Syntax and Examples

Overview of Oracle Data Pump
Oracle Data Pump technology enables high-speed movement of data and metadata
from one database to another. Oracle Data Pump has two command-line clients,
expdp and impdp, that invoke Data Pump Export utility and Data Pump Import
utility, respectively. The expdp and impdp clients use procedures provided in PL/SQL
package DBMS_DATAPUMP to execute export and import commands, passing the
parameters entered at the command-line. These parameters enable the exporting and
importing of data and metadata for a complete database or subsets of a database.
The Data Pump Export and Import utilities (invoked with commands expdp and
impdp, respectively) have a similar look and feel to the original Export (exp) and
Import (imp) utilities, but they are completely separate.
Oracle Database Utilities, for information about situations
in which you should still use the original Export and Import utilities.

See Also:

Data Pump Export utility (invoked with expdp) unloads data and metadata into a set
of operating system files called a dump file set. The dump file set can be imported only
by the Data Pump Import utility (invoked with impdp).

Exporting and Importing XMLType Tables

36-1

EXPORT/IMPORT Support in Oracle XML DB

EXPORT/IMPORT Support in Oracle XML DB
Oracle XML DB supports export and import of XMLType tables and columns that store
XML data.
You can export and import this data regardless of the XMLType storage format
(structured, unstructured, or binary XML). However, Data Pump exports and imports
XML data as text or binary XML data only. The underlying object-relational tables and
columns used for structured storage of XMLType are thus not exported. Instead, they
are converted to binary form and then exported as self-describing binary XML data.
XMLType data stored as CLOB instances (unstructured storage) is exported as text.
Oracle Data Pump for Oracle Database 11g Release 1 (11.1)
does not support the export of XML schemas, XML schema-based
XMLType columns, or binary XML data to database releases prior to
11.1.

Note:

Regardless of the export format, the format of the dump file is either CLOB or
self-describing binary XML with a token map preamble. How Oracle Data Pump
stores this data in the dump file depends on the value of the export parameter, data_
options (the only valid value for this parameter is xml_clobs.) If you specify this
value on the export command line, all XMLType data is stored in text format in the
dump file. If you do not specify the xml_clobs parameter in the expdp command,
then the format of the XMLType columns in the table determines the format of the data
in the dump file. Table 36–1 shows the format of the XMLType columns in the table
with the corresponding format of the dump file.
Table 36–1 Format of the XMLType columns in the table with the corresponding format
of the dump file
Storage Model of XMLType Columns

Dump File Format of XML Data

Unstructured storage

Text

Structured storage, binary XML storage, or hybrid storage
(a mixture of unstructured and structured storage)

Self-describing binary XML

Since XMLType data is exported and imported as XML data, the source and target
databases can use different XMLType storage models for that data. You can export data
from a database that stores XMLType data one way and import it into a database that
stores XMLType data a different way.

When importing using an external table, do not use option
append to import more than once from the same dump file into an
XMLType table or column, regardless of the XMLType storage model
used. Doing so raises a unique-constraint violation error.

Note:

See Oracle Database Utilities for information about importing using an
external table.

Exporting XML Schema-Based XMLType Tables
You can export XMLType tables, whether they are XML schema-based or not. If a table
is XML schema-based, then it depends on the XML schema used to define its data.
This XML schema can also have dependencies on SQL object types that are used to
36-2 Oracle XML DB Developer's Guide

Repository Resources and Foldering Support

store the data, in the case of structured storage. Therefore, exporting a user who has
XML schema-based XMLType tables also exports the following:
■

SQL objects types (if structured storage was used)

■

XML schemas

■

XML tables

Exporting Hierarchy-Enabled (Repository) Tables
The following guidelines apply to exporting hierarchy-enabled tables, that is, tables
that underlie Oracle XML DB Repository data:
■

■

The row-level security (RLS) policies and path-index triggers are not exported for
hierarchy-enabled tables. When these tables are imported, they are not
hierarchy-enabled.
Hidden columns ACLOID and OWNERID are not exported for these tables. In an
imported database the values of these columns could be different, so they should
be reinitialized.
See Also: "Repository Resources and Database Table Security" on
page 27-18 for information about RLS policies and path-index triggers

Exporting and Importing Transportable Tablespaces
Using the transportable tablespace feature, you can move a set of tablespaces from one
Oracle database to another, whether it is XML schema-based or non-schema-based.
When you export using transportable tablespaces mode, only the metadata for tables
(and their dependent objects) within a specified set of tablespaces are unloaded. You
can then copy the tablespace data files to another Oracle database and perform a
transport tablespace import. This is generally very fast, because it involves only
copying the tablespace and re-creating the tablespace metadata.
Use TRANSPORT_TABLESPACES parameter in expdp to specify a list of tablespace
names for which the object metadata is to be exported from the source database to the
target database.
You cannot export transportable tablespaces and import them to a database at a lower
release level. The target database must be at the same or higher release level as the
source database.
When exporting, Oracle XML DB Repository hierarchy information is lost (see
"Exporting Hierarchy-Enabled (Repository) Tables" on page 36-3). When importing, any
XML schemas referenced by the data to be imported are also imported.

Repository Resources and Foldering Support
Oracle XML DB supports a foldering mechanism that helps store content in the database
in hierarchical structures, as opposed to traditional relational database structures.
Foldering lets you use path names and URIs to refer to data (repository resources),
rather than table names, column names, and so on. This foldering mechanism is not
entirely supported using expdp or impdp.
However, for resources based on a registered XML schema, the XMLType tables storing
the data can be exported and imported. During export, only the XML data is exported,
the relationship in the Oracle XML DB foldering hierarchy is lost.

Exporting and Importing XMLType Tables

36-3

Export/Import Syntax and Examples

Full Database Export
Oracle XML DB stores the metadata (and data unrelated to XML Schema) for Oracle
XML DB Repository in database schema (user account) XDB. Because Oracle Database
does not export the repository structure, these metadata tables and structures are not
exported during a full database export.
The entire database schema (user) XDB is skipped during a full database export, and
any database objects owned by user XDB are not exported.

Exporting and Importing with Different Character Sets
As with other database objects, XML data is exported in the character set of the
exporting server. During import, the data gets converted to the character set of the
importing server.

Export/Import Syntax and Examples
Export and import using Oracle Data Pump is described in Oracle Database Utilities.
This section includes additional guidelines and examples for using commands expdp
and impdp with XMLType data. For tables with XMLType data stored as CLOB, Oracle
Data Pump exports and imports the tables in the same way as it would do for any
table.
The examples presented here use the command-line commands expdp and impdp.
After submitting such a command with a user name and command parameters, you
are prompted for a password. The examples here do not show this prompting.

Performing a Table-Mode Export /Import
An XMLType table has a dependency on the XML schema that was used to define it.
Similarly, the XML schema has dependencies on the SQL object types created or
specified for it. Importing an XMLType table requires the existence of the XML schema
and the SQL object types. When a TABLE mode export is used, only the table related
metadata and data are exported. To be able to import this data successfully, the user
needs to ensure that both the XML schema and object types have been created.
The examples here assume that you are using a database with the following features:
■

A database with a sample schema

■

A table foo with an XMLType column in unstructured (CLOB) storage format

■

A directory object dpump_dir, for which READ and WRITE privileges have been
granted to the sample schema

Example 36–1 shows a table-mode export, specified using the TABLES parameter. It
exports table foo to foo.dmp dump file.
Example 36–1

Exporting XMLType Data in TABLE Mode

expdp system directory=dpump_dir dumpfile=foo.dmp tables=foo

In table mode, if you do not specify a schema prefix in the
expdp command, the schema of the exporter is used by default.

Note:

Example 36–2 shows a table-mode import. It imports table foo from the foo.dmp
dump file.

36-4 Oracle XML DB Developer's Guide

Export/Import Syntax and Examples

Example 36–2

Importing XMLType Data in TABLE Mode

impdp system tables=foo directory=dpump_dir dumpfile=foo.dmp table_exists_action=append

If a table by the name foo already exists at the time of this import, then parameter
table_exists_action appends rows at the end of the existing table. When you use
APPEND, the data is always loaded into new space. Existing space, even if available, is
never reused. For this reason, you might need to compress your data after the load.
Oracle Database Utilities, for more information about
Oracle Data Pump and its command-line clients, expdp and impdp

See Also:

Performing a Schema-Mode Export/Import
When performing a Schema mode export, if you have role EXP_FULL_DATABASE,
then you can export a database schema, the database schema definition, and the
system grants and privileges of that database schema.
The example here assumes that you are using a database with the following features:
■
■

User x4a has created a table po2.
User x4a has a registered XML schema, ipo, which created two ordered collection
tables item_oct2 and sitem_nt2.

User x4a creates table po2 as shown in Example 36–3.
Example 36–3

Creating Table po2

CREATE TABLE po2 (po XMLType)
XMLTYPE COLUMN po
XMLSCHEMA "ipo.xsd"
ELEMENT "purchaseOrder"
VARRAY po.XMLDATA."items"."item"
STORE AS TABLE item_oct2 ((PRIMARY KEY(NESTED_TABLE_ID, SYS_NC_ARRAY_INDEX$)))
NESTED TABLE po.XMLDATA."shippedItems"."item" STORE AS sitem_nt2;

Table po2 is then populated and exported, as shown in Example 36–4.
Example 36–4

Exporting XMLType Data in SCHEMA Mode

expdp x4a directory=tkxm_xmldir dumpfile=x4a.dmp

Example 36–4 exports all of the following:
■

All data types that were generated during registration of XML schema ipo.

■

XML schema ipo.

■

■

Table po2 and the ordered collection tables item_oct2 and sitem_nt2, which
were generated during registration of XML schema ipo.
All data in all of those tables.

Example 36–5

Importing XMLType Data in SCHEMA Mode

impdp x4a directory=tkxm_xmldir dumpfile=x4a.dmp

Example 36–5 imports all of the data in x4a.dmp to another database, in which the
user x4a already exists.
Example 36–6 does the same thing as Example 36–5, but it also remaps the database
schema from user x4a to user quine.

Exporting and Importing XMLType Tables

36-5

Export/Import Syntax and Examples

Example 36–6

Importing XMLType Data in SCHEMA Mode, Remapping Schema

impdp x4a directory=tkxm_xmldir dumpfile=x4a.dmp remap_schema=x4a:quine

Example 36–6 imports all of the data in x4a.dmp (exported from the database schema
of user x4a) into database schema quine. To remap the database schema, user x4a
must have been granted role IMP_FULL_DATABASE on the local database and role
EXP_FULL_DATABASE on the source database. REMAP_SCHEMA loads all of the objects
from the source schema into the target schema.

36-6 Oracle XML DB Developer's Guide

37
Exchanging XML Data using Oracle
Streams AQ
Oracle Streams Advanced Queuing (AQ) provides database-integrated
message-queuing:
■

■

It enables and manages asynchronous communication of two or more
applications, using messages
It supports point-to-point and publish/subscribe communication models

Integration of message queuing with Oracle Database brings the integrity, reliability,
recoverability, scalability, performance, and security features of Oracle Database to
message queuing. It also facilitates the extraction of intelligence from message flows.
This chapter describes how XML data can be exchanged using AQ. It contains these
topics:
■

How Do AQ and XML Complement Each Other?

■

Oracle Streams and AQ

■

XMLType Attributes in Object Types

■

Internet Data Access Presentation (iDAP)

■

iDAP Architecture

■

Guidelines for Using XML and Oracle Streams Advanced Queuing

How Do AQ and XML Complement Each Other?
XML has emerged as a standard format for business communications. XML is being
used not only for data communicated between business applications, but also to
represent business logic.
In Oracle Database, AQ supports native XML messages. It lets AQ operations be
defined using the XML-based Internet-Data-Access-Presentation (iDAP) format. iDAP
is an extensible message invocation protocol. It is built on Internet standards, using
HTTP(S) and e-mail protocols as the transport mechanism. XML is the data
representation language for iDAP.

AQ and XML Message Payloads
Figure 37–1 shows an Oracle database using AQ to communicate with three
applications. The message payload is XML data. The general tasks performed by AQ
in this scenario are:

Exchanging XML Data using Oracle Streams AQ 37-1

How Do AQ and XML Complement Each Other?

■

Message flow using subscription rules

■

Message management

■

Extraction of business intelligence from messages

■

Message transformation

XML messages are passed asynchronously among applications using AQ.
■

■

Intra-business. Typical examples include sales order fulfillment and supply-chain
management.
Inter-business. Multiple integration hubs can communicate over the Internet.
Examples include travel reservations, coordination between manufacturers and
suppliers, transfer of funds between banks, and insurance claims settlements.
Oracle uses this approach in its enterprise application integration products. XML
messages are sent from applications to an Oracle AQ hub. The hub serves as a
message server for any application that wants the message. Through this
hub-and-spoke architecture, XML messages can be communicated asynchronously
to multiple loosely coupled applications.

Figure 37–1 shows XML payload messages transported using AQ in the following
ways:
■

■
■

A Web-based application uses an AQ operation over an HTTP(S) connection using
iDAP
An application uses AQ to propagate an XML message over a Net* connection
An application uses AQ to propagate an Internet or XML message directly to the
database using HTTP(S) or SMTP

Figure 37–1 also shows that AQ clients can access data using OCI, Java, or PL/SQL.

37-2 Oracle XML DB Developer's Guide

Oracle Streams and AQ

Figure 37–1 Oracle Streams Advanced Queuing and XML Message Payloads
XML-Based Internet
Transport
(HTTP(s), SMTP)

Internet Users

OCI, PL/SQL,
Java clients
Oracle

Internet Access
Rules and
Transformations
Advanced
queues

MQ Series

Internet
Propagation

Internet
Propagation
(Oracle
Net)

Rules and
Transformations

Rules and
Transformations

Advanced
queues

Advanced
queues
Global Agents,
Global Subscriptions,
Global Events

Advantages of Using AQ
AQ provides flexibility in configuring communication between different applications.
It makes an integrated solution easy to manage, easy to configure, and easy to modify,
to meet changing business needs. It enables multiple applications to cooperate,
coordinate, and synchronize, to carry out complex business transactions.
Message management provided by AQ manages the flow of messages between
different applications. AQ can also retain messages for auditing and tracking
purposes, and for extracting business intelligence.
AQ provides SQL views to access messages. You can use these views to analyze
trends.

Oracle Streams and AQ
Oracle Streams (Streams) enables you to share data and events in a stream. The stream
can propagate this information within a database or from one database to another. The
stream routes specified information to specified destinations. This provides greater
functionality and flexibility than traditional solutions for capturing and managing
events, and sharing the events with other databases and applications.
Streams enables you to break the cycle of trading off one solution for another. It enable
you to build and operate distributed enterprises and applications, data warehouses,
and high availability solutions. You can use all the capabilities of Oracle Streams at the
same time.
You can use Streams to:
■

Capture changes at a database. You can configure a background capture process to
capture changes made to tables, database schemas, or the entire database. A
capture process captures changes from the redo log and formats each captured
Exchanging XML Data using Oracle Streams AQ 37-3

XMLType Attributes in Object Types

change into a logical change record (LCR). The database where changes are
generated in the redo log is called the source database.
■

■

■

■

Enqueue events into a queue. Two types of events may be staged in a Streams queue:
LCRs and user messages. A capture process enqueues LCR events into a queue
that you specify. The queue can then share the LCR events within the same
database or with other databases. You can also enqueue user events explicitly with
a user application. These explicitly enqueued events can be LCRs or user
messages.
Propagate events from one queue to another. These queues may be in the same
database or in different databases.
Dequeue events. A background apply process can dequeue events. You can also
dequeue events explicitly with a user application.
Apply events at a database. You can configure an apply process to apply all of the
events in a queue or only the events that you specify. You can also configure an
apply process to call your own PL/SQL subprograms to process events.
The database where LCR events are applied and other types of events are
processed is called the destination database. In some configurations, the source
database and the destination database may be the same.

Streams Message Queuing
Streams lets user applications:
■

Enqueue messages of different types

■

Propagate messages are ready for consumption

■

Dequeue messages at the destination database

Streams introduces a new type of queue that stages messages of type SYS.AnyData.
Messages of almost any type can be wrapped in a SYS.AnyData wrapper and staged
in SYS.AnyData queues. Streams interoperates with Advanced Queuing (AQ), which
supports all the standard features of message queuing systems, including
multiconsumer queues, publishing and subscribing, content-based routing, internet
propagation, transformations, and gateways to other messaging subsystems.
See Also: Oracle Streams Concepts and Administration, and its
Appendix A, "XML Schema for LCRs".

XMLType Attributes in Object Types
You can create queues that use Oracle object types containing XMLType attributes.
These queues can be used to transmit and store messages that are XML documents.
Using XMLType, you can do the following:
■

Store any type of message in a queue

■

Store documents internally as CLOB values

■

Store more than one type of payload in a queue

■

Query XMLType columns using SQL/XML functions such as XMLExists

■

Specify the operators in subscriber rules or dequeue selectors

37-4 Oracle XML DB Developer's Guide

iDAP Architecture

Internet Data Access Presentation (iDAP)
You can access AQ over the Internet by using SOAP. Internet Data Access Presentation
(iDAP) is the SOAP specification for AQ operations. iDAP defines XML message
structure for the body of the SOAP request. An iDAP-structured message is
transmitted over the Internet using transport protocols such as HTTP(S) and SMTP.
iDAP uses the text/xml content type to specify the body of the SOAP request. XML
provides the presentation for iDAP request and response messages as follows:
■

All request and response tags are scoped in the SOAP namespace.

■

AQ operations are scoped in the iDAP namespace.

■

■

■

■

The sender includes namespaces in iDAP elements and attributes in the SOAP
body.
The receiver processes iDAP messages that have correct namespaces. For the
requests with incorrect namespaces, the receiver returns an invalid request error.
The SOAP namespace has this value:
http://schemas.xmlsoap.org/soap/envelope/
The iDAP namespace has this value:
http://ns.oracle.com/AQ/schemas/access
See Also:

Oracle Streams Advanced Queuing User's Guide

iDAP Architecture
Figure 37–2 shows the following components needed to send HTTP(S) messages:
■

■

■

A client program that sends XML messages, conforming to iDAP format, to the
AQ Servlet. This can be any HTTP client, such as Web browsers.
The Web server or ServletRunner which hosts the AQ servlet that can interpret
the incoming XML messages, for example, Apache/Jserv or Tomcat.
Oracle Server/Database. Oracle Streams AQ servlet connects to Oracle Database to
perform operations on your queues.

Figure 37–2 iDAP Architecture for Performing AQ Operations using HTTP(S)
XML
Messages
over HTTP

Oracle Database
Server
AQ
Servlet

AQ Client

AQ Queue
Web Server

XMLType Queue Payloads
You can create queues with payloads that contain XMLType attributes. These can be
used for transmitting and storing messages that contain XML documents. By defining
Oracle objects with XMLType attributes, you can do the following:
■

Store more than one type of XML document in the same queue. The documents
are stored internally as CLOB instances.

Exchanging XML Data using Oracle Streams AQ 37-5

iDAP Architecture

■

■
■

Selectively dequeue messages with XMLType attributes using SQL/XML functions
such as XMLExists and XMLQuery.
Define transformations to convert Oracle objects to XMLType.
Define rule-based subscribers that query message content using SQL/XML
functions such as XMLExists and XMLQuery.

In the BooksOnline application, assume that the Overseas Shipping site represents an
order using SYS.XMLType. The Order Entry site represents an order as an Oracle
object, ORDER_TYP.
Example 37–1 creates the queue table and queue for Overseas Shipping.
Example 37–1

Creating a Queue Table and Queue

BEGIN
DBMS_AQADM.create_queue_table(
queue_table
=> 'OS_orders_pr_mqtab',
comment
=> 'Overseas Shipping MultiConsumer Orders queue table',
multiple_consumers => TRUE,
queue_payload_type => 'SYS.XMLtype',
compatible
=> '8.1');
END;
/
BEGIN
DBMS_AQADM.create_queue(queue_name
queue_table
END;
/

=> 'OS_bookedorders_que',
=> 'OS_orders_pr_mqtab');

Because the representation of orders at the overseas shipping site is different from the
representation of orders at the order-entry site, messages need to be transformed
before sending them from the order-entry site to the overseas shipping site.
Example 37–2 creates the transformation, and Example 37–3 applies it.
Example 37–2

Creating a Transformation to Convert Message Data to XML

CREATE OR REPLACE FUNCTION convert_to_order_xml(input_order ORDER_TYP)
RETURN XMLType AS
new_order XMLType;
BEGIN
SELECT sys_xmlgen(input_order) INTO new_order FROM DUAL;
RETURN new_order;
END convert_to_order_xml;
/
BEGIN
SYS.DBMS_TRANSFORM.create_transformation(
schema =>
'OE',
name
=>
'OE2XML',
from_schema =>
'OE',
from_type =>
'ORDER_TYP',
to_schema =>
'SYS',
to_type =>
'XMLTYPE',
transformation => 'convert_to_order_xml(source.user_data)');
END;
/

37-6 Oracle XML DB Developer's Guide

iDAP Architecture

Example 37–3

Applying a Transformation before Sending Messages Overseas

-- Add a rule-based subscriber for overseas shipping to the booked-orders
-- queues with transformation.
DECLARE
subscriber SYS.AQ$_AGENT;
BEGIN
subscriber := SYS.AQ$_AGENT('Overseas_Shipping',
'OS.OS_bookedorders_que',
NULL);
DBMS_AQADM.add_subscriber(
queue_name
=> 'OS_bookedorders_que',
subscriber
=> subscriber,
rule
=> 'XMLSerialize(CONTENT XMLQuery(''//orderregion''' ||
'PASSING tab.user_data RETURNING CONTENT)' ||
' AS VARCHAR2(1000)) = ''INTERNATIONAL''',
transformation => 'OE.OE2XML');
END;
/

For more information about defining transformations that convert the type used by the
order entry application to the type used by Overseas Shipping, see Oracle Streams
Advanced Queuing User's Guide.
Example 37–4 shows how an application that processes orders for customers in
another country, in this case Canada, can dequeue messages.
Example 37–4

XMLType and AQ: Dequeuing Messages

-- Create procedure to enqueue into single-consumer queues.
CREATE OR REPLACE PROCEDURE get_canada_orders AS
deq_msgid
RAW(16);
dopt
DBMS_AQ.dequeue_options_t;
mprop
DBMS_AQ.message_properties_t;
deq_order_data
SYS.XMLType;
deq_order_data_text
CLOB;
no_messages
EXCEPTION;
PRAGMA EXCEPTION_INIT (no_messages, -25228);
new_orders
BOOLEAN := TRUE;
BEGIN
dopt.wait := 1;
-- Specify dequeue condition to select orders for Canada.
dopt.deq_condition := 'XMLSerialize(CONTENT ' ||
'XMLQuery(''/ORDER_TYP/CUSTOMER/COUNTRY/text()''' ||
' PASSING tab.user_data RETURNING CONTENT)' ||
' AS VARCHAR2(1000))=''CANADA''';
dopt.consumer_name := 'Overseas_Shipping';
WHILE (new_orders) LOOP
BEGIN
DBMS_AQ.dequeue(queue_name
=> 'OS.OS_bookedorders_que',
dequeue_options
=> dopt,
message_properties => mprop,
payload
=> deq_order_data,
msgid
=> deq_msgid);
COMMIT;
SELECT XMLSerialize(DOCUMENT deq_order_data AS CLOB)
INTO deq_order_data_text FROM DUAL;
DBMS_OUTPUT.put_line('Order for Canada - Order: ' || deq_order_data_text);
EXCEPTION
WHEN no_messages THEN
DBMS_OUTPUT.put_line (' ---- NO MORE ORDERS ---- ');

Exchanging XML Data using Oracle Streams AQ 37-7

Guidelines for Using XML and Oracle Streams Advanced Queuing

new_orders := FALSE;
END;
END LOOP;
END;
/

Guidelines for Using XML and Oracle Streams Advanced Queuing
This section describes guidelines for using XML and Oracle Streams Advanced
Queuing.

Storing Oracle Streams AQ XML Messages with Many PDFs as One Record?
You can exchange XML documents between businesses using Oracle Streams
Advanced Queuing, where each message received or sent includes an XML header,
XML attachment (XML data stream), DTDs, and PDF files, and store the data in a
database table, such as a queuetable. You can enqueue the messages into Oracle
queue tables as one record or piece. Or you can enqueue the messages as multiple
records, such as one record for XML data streams as CLOB type, one record for PDF
files as RAW type, and so on. You can also then dequeue the messages.
You can achieve this in the following ways:
■

■

By defining an object type with (CLOB, RAW,...) attributes, and storing it as a single
message.
By using the AQ message grouping feature and storing it in multiple messages.
Here the message properties are associated with a group. To use the message
grouping feature, all messages must be the same payload type.

To specify the payload, first create an object type, for example:
CREATE TYPE mypayload_type as OBJECT (xmlDataStream CLOB, dtd CLOB, pdf BLOB);

then store it as a single message.

Adding New Recipients After Messages Are Enqueued
You can use the queue table to support message assignments. For example, when other
businesses send messages to a specific company, they do not know who should be
assigned to process the messages, but they know the messages are for Human
Resources (HR) for example. Hence all messages go to the HR supervisor. At this
point, the message is enqueued in the queue table. The HR supervisor is the only
recipient of this message, and the entire HR staff have been pre-defined as subscribers
for this queue.
You cannot change the recipient list after the message is enqueued. If you do not
specify a recipient list then subscribers can subscribe to the queue and dequeue the
message. Here, new recipients must be subscribers to the queue. Otherwise, you must
dequeue the message and enqueue it again with new recipients.

Enqueuing and Dequeuing XML Messages?
Oracle Streams AQ supports enqueuing and dequeuing objects. These objects can have
an attribute of type XMLType that contains an XML document, in addition to metadata
attributes. Refer to Oracle Streams Advanced Queuing User's Guide for specific details
and more examples.

37-8 Oracle XML DB Developer's Guide

Guidelines for Using XML and Oracle Streams Advanced Queuing

Parsing Messages with XML Content from Oracle Streams AQ Queues
You can parse messages with XML content from an Oracle Streams AQ queue and
then update tables and fields in an ODS (Operational Data Store).
You can use Oracle XML Parser for Java and Java Stored Procedures together with
Oracle Streams AQ to obtain metadata such as AQ enqueue or dequeue times and JMS
header information, based on queries that target certain XML data. You can combine
this with using Oracle Text XML search.
See Also:

Chapter 12, "Full-Text Search Over XML Data".

Preventing the Listener from Stopping Until the XML Document Is Processed
When receiving XML messages from clients as messages you may need to process
them as soon as they arrive. But each XML document might take several seconds to
process. For PL/SQL, one procedure starts the listener, dequeues the message, and
calls another procedure to process the XML document. The listener could be held up
until the XML document is processed, and messages would accumulate in the queue.
After receiving a message, you can instead submit a job using PL/SQL package DBMS_
JOB. The job is invoked asynchronously in a different database session.
You can register a PL/SQL callback, which is invoked asynchronously when a
message shows up in a queue. PL/SQL callbacks are part of the Oracle Streams AQ
notification framework.

Using HTTPS with AQ
You can use Oracle Streams AQ Internet access to send XML messages to suppliers
using HTTPS and receive a response. Using XML, you can enqueue and dequeue
messages over HTTP(S) securely and transactionally.
See Also:

Oracle Streams Advanced Queuing User's Guide

Storing XML in Oracle Streams AQ Message Payloads
You can store XML data in Oracle Streams AQ message payloads natively other than
having an ADT as the payload with SYS.XMLType as part of the ADT. You can create
queues with payloads and attributes as XMLType.

Comparing iDAP and SOAP
iDAP is the SOAP specification for AQ operations. iDAP is the XML specification for
Oracle Streams AQ operations. SOAP defines a generic mechanism to invoke a service.
iDAP defines these mechanisms to perform AQ operations.
iDAP has the following key properties not defined by SOAP:
■

■

Transactional behavior. You can perform AQ operations in a transactional manner.
A transaction can span multiple iDAP requests.
Security. iDAP operations can be carried out only by authorized and authenticated
users.

Exchanging XML Data using Oracle Streams AQ 37-9

Guidelines for Using XML and Oracle Streams Advanced Queuing

37-10 Oracle XML DB Developer's Guide

Part VII
Appendixes
Part VII of this manual provides background material as a set of appendixes:
■

Appendix A, "Oracle-Supplied XML Schemas and Examples"

■

Appendix B, "Oracle XML DB Restrictions"

A
Oracle-Supplied XML Schemas and
Examples
This appendix includes the definition and structure of RESOURCE_VIEW and PATH_
VIEW and the Oracle XML DB-supplied XML schemas. It also includes a full listing of
the purchase-order XML schemas used in various examples, and the C example for
loading XML content into Oracle XML DB.
This appendix contains these topics:
■

XDBResource.xsd: XML Schema for Oracle XML DB Resources

■

XDBResConfig.xsd: XML Schema for Resource Configuration

■

acl.xsd: XML Schema for ACLs

■

xdbconfig.xsd: XML Schema for Configuring Oracle XML DB

■

xdiff.xsd: XML Schema for Comparing Schemas for In-Place Evolution

■

Purchase-Order XML Schemas

■

XSL Style Sheet Example, PurchaseOrder.xsl

■

Loading XML Data using C (OCI)

■

Initializing and Terminating an XML Context (OCI)

XDBResource.xsd: XML Schema for Oracle XML DB Resources
Here is the complete listing for the Oracle XML DB supplied XML schema,
XDBResource.xsd, which is used to represent Oracle XML DB resources.

XDBResource.xsd











Oracle-Supplied XML Schemas and Examples

A-1

XDBResource.xsd: XML Schema for Oracle XML DB Resources

















































































Oracle-Supplied XML Schemas and Examples

A-3

XDBResource.xsd: XML Schema for Oracle XML DB Resources


































































XDBResConfig.xsd: XML Schema for Resource Configuration
This section presents the Oracle XML DB supplied XML schema used to configure
repository resources. This is accessible in Oracle XML DB Repository at path
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/XDBResConfig.xsd.

XDBResConfig.xsd



This XML schema declares the schema of an XDB resource configuration,
which includes default ACL, event listeners and user configuration.
It lists all XDB repository events that will be supported.

Oracle-Supplied XML Schemas and Examples

A-9

XDBResConfig.xsd: XML Schema for Resource Configuration

Future extension can be added to support user-defined events and
XML events.



























































A-10 Oracle XML DB Developer's Guide

XDBResConfig.xsd: XML Schema for Resource Configuration






























































Oracle-Supplied XML Schemas and Examples A-11

XDBResConfig.xsd: XML Schema for Resource Configuration






























































A-12 Oracle XML DB Developer's Guide

acl.xsd: XML Schema for ACLs
























acl.xsd: XML Schema for ACLs
This section presents the Oracle Database supplied XML schema used to represent
access control lists (ACLs).

acl.xsd



This XML schema describes the structure of XDB ACL documents.
Note : The "systemPrivileges" element below lists all supported
system privileges and their aggregations.
See dav.xsd for description of DAV privileges
Note : The elements and attributes marked "hidden" are for
internal use only.
















Oracle-Supplied XML Schemas and Examples A-13

acl.xsd: XML Schema for ACLs













































A-14 Oracle XML DB Developer's Guide

acl.xsd: XML Schema for ACLs


















































Oracle-Supplied XML Schemas and Examples A-15

xdbconfig.xsd: XML Schema for Configuring Oracle XML DB


























xdbconfig.xsd: XML Schema for Configuring Oracle XML DB
File xdbconfig.xsd contains the Oracle XML DB supplied XML schema used to
configure Oracle XML DB.
The value of attribute value of element pattern has been
split here for documentation purposes. In reality, the value is not split
(no newline characters), but is one long string.

Note:

xdbconfig.xsd
















A-16 Oracle XML DB Developer's Guide

xdbconfig.xsd: XML Schema for Configuring Oracle XML DB




































































































































Oracle-Supplied XML Schemas and Examples A-19

xdbconfig.xsd: XML Schema for Configuring Oracle XML DB















































A-20 Oracle XML DB Developer's Guide

xdbconfig.xsd: XML Schema for Configuring Oracle XML DB


















































Oracle-Supplied XML Schemas and Examples A-21

xdbconfig.xsd: XML Schema for Configuring Oracle XML DB


























































A-22 Oracle XML DB Developer's Guide

xdbconfig.xsd: XML Schema for Configuring Oracle XML DB





















































































































A-24 Oracle XML DB Developer's Guide

xdbconfig.xsd: XML Schema for Configuring Oracle XML DB




























































Oracle-Supplied XML Schemas and Examples A-25

xdbconfig.xsd: XML Schema for Configuring Oracle XML DB

























































A-26 Oracle XML DB Developer's Guide

xdbconfig.xsd: XML Schema for Configuring Oracle XML DB





































































1










xdiff.xsd: XML Schema for Comparing Schemas for In-Place Evolution
xdiff.xsd, is the Oracle XML DB-supplied XML schema to which the document
specified as the diffXML parameter to procedure DBMS_
XMLSCHEMA.inPlaceEvolve must conform.

xdiff.xsd



Defines the structure of XML documents that capture the difference
between two XML documents. Changes that are not supported by Oracle
XmlDiff may not be expressible in this schema.
'oracle-xmldiff' PI:
We use 'oracle-xmldiff' PI to describe certain aspects of the diff.
This should be the first element of top level xdiff element.
operations-in-docorder:
1

The value of attribute value has been split here for documentation purposes. In reality, the
value is one long string, with no line breaks.

A-28 Oracle XML DB Developer's Guide

xdiff.xsd: XML Schema for Comparing Schemas for In-Place Evolution

Can be either 'true' or 'false'.
If true, the operations in the diff document refer to the
elements of the input doc in the same order as document order. Output of
global algorithm meets this requirement while local does not.
output-model: output models for representing the diff. Can be either
'Snapshot' or 'Current'.
Snapshot model:
Each operation uses Xpaths as if no operations
have been applied to the input document. (like UNIX diff)
Default and works for both Xmldiff and XmlPatch.
For XmlPatch to handle this model, "operations-in-docorder" must be
true and the Xpaths must be simple. (see XmlDif C API documentation).
Current model :
Each operation uses Xpaths as if all operations till the previous one
have been applied to the input document. Not implemented for Xmldiff.
Works with XmlPatch.




































Oracle-Supplied XML Schemas and Examples A-29

Purchase-Order XML Schemas











































Purchase-Order XML Schemas
This section contains the complete listings of the annotated purchase-order XML
schemas used in various examples, particularly in Chapter 3. Example A–2 represents
a modified version of Example A–1. The modification is used in Chapter 10 to
illustrate XML schema evolution.
Example A–1 is the complete listing of the annotated XML schema presented in
Example 3–10 on page 3-20.
Example A–1 Annotated Purchase-Order XML Schema, purchaseOrder.xsd


A-30 Oracle XML DB Developer's Guide

Purchase-Order XML Schemas































































Oracle-Supplied XML Schemas and Examples A-31

Purchase-Order XML Schemas




































































A-32 Oracle XML DB Developer's Guide

Purchase-Order XML Schemas
























Example A–2 is the complete listing of the revised annotated XML schema presented
in Example 10–1 on page 10-2. Text that is in bold face is additional or significantly
different from that in the schema of Example A–1.
Example A–2 Revised Purchase-Order XML Schema



















Oracle-Supplied XML Schemas and Examples A-33

Purchase-Order XML Schemas
































































A-34 Oracle XML DB Developer's Guide

Purchase-Order XML Schemas




































































Oracle-Supplied XML Schemas and Examples A-35

Purchase-Order XML Schemas




































































A-36 Oracle XML DB Developer's Guide

Purchase-Order XML Schemas




































































Oracle-Supplied XML Schemas and Examples A-37

XSL Style Sheet Example, PurchaseOrder.xsl






















XSL Style Sheet Example, PurchaseOrder.xsl
Example A–3 shows XSLT style sheet PurchaseOrder.xsl. The example style sheet
is used in examples in Chapter 3, "Using Oracle XML DB".
Example A–3 PurchaseOrder.xsl Style Sheet












Purchase Order 



















A-38 Oracle XML DB Developer's Guide

XSL Style Sheet Example, PurchaseOrder.xsl

















Internal


...





Ship To







...

These is nothing Oracle XML DB-specific about the style sheet of Example 3–47. A
style sheet can be stored in an XMLType table or column or stored as
non-schema-based XML data inside Oracle XML DB Repository.
Performing transformations inside the database lets Oracle XML DB optimize features
such as memory usage, I/O operations, and network traffic. These optimizations are
particularly effective when the transformation operates on a small subset of the nodes
in the source document.
In traditional XSL processors, the entire source document must be parsed and loaded
into memory before XSL processing can begin. This process requires significant
amounts of memory and processor. When only a small part of the document is
processed this is inefficient.
When Oracle XML DB performs XSL transformations on a schema-based XML
document there is no need to parse the document before processing can begin. The
lazily loaded virtual DOM eliminates the need to parse the document, by loading
content directly from disk as the nodes are accessed. The lazy load also reduces the
amount of memory required to perform the transformation, because only the parts of
the document that are processed are loaded into memory.

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XSL Transformation and Oracle XML DB

Example 3–48 shows how to use SQL function XMLtransform to apply an XSL style
sheet to a document stored in an XMLType table, producing HTML code. SQL function
XDBURIType reads the XSL style sheet from Oracle XML DB Repository.
In the interest of brevity, only part of the result of the transformation is shown in
Example 3–48. Omitted parts are indicated with an ellipsis (. . .). Figure 3–7 shows
what the transformed result looks like in a Web browser.
Example 3–48

Applying a Style Sheet using TRANSFORM

SELECT
XMLtransform(
OBJECT_VALUE,
XDBURIType('/source/schemas/poSource/xsl/purchaseOrder.xsl').getXML())
FROM purchaseorder
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
XMLTRANSFORM(OBJECT_VALUE, XDBURITYPE('/SOURCE/SCHEMAS/POSOURCE/XSL/PURCHASEORDER.XSL').GET
--------------------------------------------------------------------------------------------






PurchaseOrder 






SBELL-2002100912333601PDT
















Internal




. . .







Ship To



Using Oracle XML DB 3-67

Using Oracle XML DB Repository


. . .








Items:






. . .




1 row selected.

See Also: Chapter 11, "Transforming and Validating XMLType
Data"

Using Oracle XML DB Repository
Oracle XML DB Repository makes it possible to organize XML content using a
file/folder metaphor. This lets you use a URL to uniquely identify XML documents
stored in the database. This approach appeals to XML developers used to using
constructs such as URLs and XPath expressions to identify content.
Oracle XML DB Repository is modelled on the DAV standard. The DAV standard uses
the term resource to describe any file or folder managed by a WebDAV server. A
resource consists of a combination of metadata and content. The DAV specification
defines the set of (system-defined) metadata properties that a WebDAV server is
expected to maintain for each resource and the set of XML documents that a DAV
server and DAV-enabled client uses to exchange metadata.
Although Oracle XML DB Repository can manage any kind of content, it provides
specialized capabilities and optimizations related to managing resources where the
content is XML.

Installing and Uninstalling Oracle XML DB Repository
All of the metadata and content managed by Oracle XML DB Repository is stored
using a set of tables in the database schema owned by database schema (user account)
XDB. User XDB is a locked account that is installed using DBCA or by running script
catqm.sql. Script catqm.sql is located in the directory ORACLE_
HOME/rdbms/admin. The repository can be uninstalled using DBCA or by running
the script catnoqm.sql. Take great care when running catnoqm.sql as it drops all
content stored in Oracle XML DB Repository and invalidates any XMLType tables or
columns associated with registered XML schemas.
See Also: Oracle Database 2 Day + Security Guide for information
about database schema XDB

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Using Oracle XML DB Repository

Oracle XML DB Provides Name-Level Locking
When using a relational database to maintain hierarchical folder structures, ensuring a
high degree of concurrency when adding and removing items in a folder is a
challenge. In conventional file system there is no concept of a transaction. Each
operation (add a file, create a subfolder, rename a file, delete a file, and so on) is treated
as an atomic transaction. Once the operation has completed the change is immediately
available to all other users of the file system.
As a consequence of transactional semantics enforced by the
database, folders created using SQL statements are not visible to
other database users until the transaction is committed. Concurrent
access to Oracle XML DB Repository is controlled by the same
mechanism used to control concurrency in Oracle Database. The
integration of the repository with Oracle Database provides strong
management options for XML content.
Note:

One key advantage of Oracle XML DB Repository is the ability to use SQL for
repository operations in the context of a logical transaction. Applications can create
long-running transactions that include updates to one or more folders. In this
situation, a conventional locking strategy that takes an exclusive lock on each updated
folder or directory tree would quickly result in significant concurrency problems.
Oracle XML DB solves this by providing for name-level locking rather than
folder-level locking. Repository operations such as creating, renaming, moving, or
deleting a sub-folder or file do not require that your operation be granted an exclusive
write lock on the target folder. The repository manages concurrent folder operations
by locking the name within the folder rather than the folder itself. The name and the
modification type are put on a queue.
Only when the transaction is committed is the folder locked and its contents modified.
Hence Oracle XML DB lets multiple applications perform concurrent updates on the
contents of a folder. The queue is also used to manage folder concurrency by
preventing two applications from creating objects with the same name.
Queuing folder modifications until commit time also minimizes I/O when a number
of changes are made to a single folder in the same transaction.
This is useful when several applications generate files quickly in the same directory,
for example when generating trace or log files, or when maintaining a spool directory
for printing or e-mail delivery.

Use Protocols or SQL to Access and Process Repository Content
You can work with content stored in Oracle XML DB Repository in these ways:
■

■

■

Using industry standard protocols such as HTTP(S), WebDAV, and FTP to perform
document-level operations such as insert, update, and delete.
By directly accessing Oracle XML DB Repository content at the table or row level,
using SQL.
Using Oracle XML DB Content Connector—see Chapter 31, "Using Oracle XML
DB Content Connector".

Using Oracle XML DB 3-69

Using Oracle XML DB Repository

Storing and Retrieving Database Content using Standard Protocols
Oracle XML DB supports industry-standard internet protocols such as HTTP(S),
WebDav, and FTP. The combination of protocol support and URL-based access makes
it possible to insert, retrieve, update, and delete content stored in Oracle Database
from standard desktop applications such as Windows Explorer, Microsoft Word, and
XMLSpy.
Figure 3–4 shows Windows Explorer used to insert a folder from the local hard drive
into Oracle Database. Windows Explorer includes support for the WebDAV protocol.
WebDAV extends the HTTP standard, adding additional verbs that allow an HTTP
server to act as a file server.
When a Windows Explorer copy operation or FTP input command is used to transfer a
number of documents into Oracle XML DB Repository, each put or post command is
treated as a separate atomic operation. This ensures that the client does not get
confused if one of the file transfers fails. It also means that changes made to a
document through a protocol are visible to other users as soon as the request has been
processed.
Figure 3–4 Copying Files into Oracle XML DB Repository

Uploading Content to Oracle XML DB using FTP
Example 3–49 shows commands issued and output generated when a standard
command line FTP tool loads documents into Oracle XML DB Repository:
Example 3–49

Uploading Content to the Repository using FTP

$ ftp mdrake-sun 2100
Connected to mdrake-sun.
220 mdrake-sun FTP Server (Oracle XML DB/Oracle Database 10g Enterprise Edition
Release 10.1.0.1.0 - Beta) ready.
Name (mdrake-sun:oracle10): QUINE
331 Password required for QUINE
Password: password
230 QUINE logged in

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ftp> cd /source/schemas
250 CWD Command successful
ftp> mkdir PurchaseOrders
257 MKD Command successful
ftp> cd PurchaseOrders
250 CWD Command successful
ftp> mkdir 2002
257 MKD Command successful
ftp> cd 2002
250 CWD Command successful
ftp> mkdir "Apr"
257 MKD Command successful
ftp> put "Apr/AMCEWEN-20021009123336171PDT.xml"
"Apr/AMCEWEN-20021009123336171PDT.xml"
200 PORT Command successful
150 ASCII Data Connection
226 ASCII Transfer Complete
local: Apr/AMCEWEN-20021009123336171PDT.xml remote:
Apr/AMCEWEN-20021009123336171PDT.xml
4718 bytes sent in 0.0017 seconds (2683.41 Kbytes/s)
ftp> put "Apr/AMCEWEN-20021009123336271PDT.xml"
"Apr/AMCEWEN-20021009123336271PDT.xml"
200 PORT Command successful
150 ASCII Data Connection
226 ASCII Transfer Complete
local: Apr/AMCEWEN-20021009123336271PDT.xml remote:
Apr/AMCEWEN-20021009123336271PDT.xml
4800 bytes sent in 0.0014 seconds (3357.81 Kbytes/s)
.....
ftp> cd "Apr"
250 CWD Command successful
ftp> ls -l
200 PORT Command successful
150 ASCII Data Connection
-rw-r--r1 QUINE oracle 0 JUN 24 15:41 AMCEWEN-20021009123336171PDT.xml
-rw-r--r1 QUINE oracle 0 JUN 24 15:41 AMCEWEN-20021009123336271PDT.xml
-rw-r--r1 QUINE oracle 0 JUN 24 15:41 EABEL-20021009123336251PDT.xml
-rw-r--r1 QUINE oracle 0 JUN 24 15:41 PTUCKER-20021009123336191PDT.xml
-rw-r--r1 QUINE oracle 0 JUN 24 15:41 PTUCKER-20021009123336291PDT.xml
-rw-r--r1 QUINE oracle 0 JUN 24 15:41 SBELL-20021009123336231PDT.xml
-rw-r--r1 QUINE oracle 0 JUN 24 15:41 SBELL-20021009123336331PDT.xml
-rw-r--r1 QUINE oracle 0 JUN 24 15:41 SKING-20021009123336321PDT.xml
-rw-r--r1 QUINE oracle 0 JUN 24 15:41 SMCCAIN-20021009123336151PDT.xml
-rw-r--r1 QUINE oracle 0 JUN 24 15:41 SMCCAIN-20021009123336341PDT.xml
-rw-r--r1 QUINE oracle 0 JUN 24 15:41 VJONES-20021009123336301PDT.xml
226 ASCII Transfer Complete
remote: -l
959 bytes received in 0.0027 seconds (349.45 Kbytes/s)
ftp> cd ".."
250 CWD Command successful
....
ftp> quit
221 QUIT Goodbye.
$

The key point demonstrated by Figure 3–4 and Example 3–49 is that neither Windows
Explorer nor an FTP tool is aware that it is working with Oracle XML DB. Since the
tools and Oracle XML DB both support open Internet protocols they work with each
other out of the box.

Using Oracle XML DB 3-71

Using Oracle XML DB Repository

Any tool that understands the WebDAV or FTP protocol can be used to create content
managed by Oracle XML DB Repository. No additional software has to installed on the
client or the mid-tier.
When the contents of the folders are viewed using a tool such as Windows Explorer or
FTP, the length of any schema-based XML documents contained in the folder is shown
as zero (0) bytes. This was designed as such for two reasons:
■

■

It is not clear what the size of the document should be. Is it the size of the CLOB
instance generated by printing the document, or the number of bytes required to
store the objects used to persist the document inside the database?
Regardless of which definition is chosen, calculating and maintaining this
information is costly.

Figure 3–5 shows Internet Explorer using a URL and the HTTP protocol to view an
XML document stored in the database.
Figure 3–5 Path-Based Access using HTTP and a URL

Accessing Oracle XML DB Repository Programmatically
Oracle XML DB Repository can be accessed and updated directly from SQL. Thus, any
application or programming language that can use SQL to interact with Oracle
Database can also access and update content stored in the repository. Oracle XML DB
includes PL/SQL package DBMS_XDB, which provides methods that allow resources to
be created, modified, and deleted programmatically.
Example 3–50 shows how to create a simple text document resource using PL/SQL
function DBMS_XDB.createResource.
Example 3–50

Creating a Text Document Resource using CREATERESOURCE

DECLARE

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Using Oracle XML DB Repository

res BOOLEAN;
BEGIN
res := DBMS_XDB.createResource('/home/QUINE/NurseryRhyme.txt',
bfilename('XMLDIR', 'tdadxdb-03-01.txt'),
nls_charset_id('AL32UTF8'));
END;
/

Accessing and Updating XML Content in the Repository
This section describes features for accessing and updating Oracle XML DB Repository
content.

Accessing XML Documents using SQL
Content stored in the repository can be accessed and updated from SQL and PL/SQL.
You can interrogate the structure of the repository in complex ways. For example, you
can query to determine how many files with extension .xsl are under a location other
than /home/mystylesheetdir.
You can also mix path-based repository access with content-based access. You can, for
example, ask "How many documents not under /home/purchaseOrders have a
node identified by the XPath /PurchaseOrder/User/text() with a value of
KING?"
All of the metadata for managing the repository is stored in a database schema owned
by database schema (user account) XDB. User XDB is created during Oracle XML DB
installation. The primary table in this schema is an XMLType table called
XDB$RESOURCE. This contains one row for each resource (file or folder) in the
repository. Documents in this table are referred to as resource documents. The XML
schema that defines the structure of an Oracle XML DB resource document is
registered under URL, "http://xmlns.oracle.com/xdb/XDBResource.xsd.
See Also: Oracle Database 2 Day + Security Guide for information
about database schema XDB

Repository Content is Exposed Through RESOURCE_VIEW and PATH_VIEW
Table XDB$RESOURCE is not directly exposed to SQL programmers. Instead, the
contents of the repository are exposed through two public views, RESOURCE_VIEW
and PATH_VIEW. Through these views, you can access and update both the metadata
and the content of documents stored in the repository.
Both views contain a virtual column, RES. Use RES to access and update resource
documents with SQL statements using a path notation. Operations on the views use
underlying tables in the repository.

Use EXISTS_PATH and UNDER_PATH for Path-Based Predicates in a WHERE
Clause
Oracle XML DB includes two repository-specific SQL functions: exists_path and
under_path. Use these functions to include path-based predicates in the WHERE
clause of a SQL statement. SQL operations can select repository content based on the
location of the content in the repository folder hierarchy. The hierarchical repository
index ensures that path-based queries are executed efficiently.
When XML schema-based XML documents are stored in the repository, the document
content is stored as an object in the default table identified by the XML schema. The

Using Oracle XML DB 3-73

Using Oracle XML DB Repository

repository contains only metadata about the document and a pointer (REF of XMLType)
that identifies the row in the default table that contains the content.

You Can Also Store Non-XML Documents in the Repository
It is also possible to store other kinds of documents in the repository. When a
document that is not XML or is not schema-based XML is stored in the repository, the
document content is stored in a LOB along with the metadata about the document.

PL/SQL Packages to Create, Delete, Rename, Move,... Folders and Documents
Because you can access and update Oracle XML DB Repository using SQL, any
application capable of calling a PL/SQL procedure can use the repository. All SQL and
PL/SQL repository operations are transactional. Access to the repository and its
contents is subject to both standard database security controls and repository access
control lists (ACLs).
With supplied PL/SQL packages DBMS_XDB, DBMS_XDBZ, and DBMS_XDB_VERSION,
you can create, delete, and rename documents and folders, move a file or folder within
the folder hierarchy, set and change the access permissions on a file or folder, and
initiate and manage versioning.
Example 3–51 uses PL/SQL package DBMS_XDB to create a set of subfolders beneath
folder /public.
Example 3–51

Creating Folders using PL/SQL Package DBMS_XDB

DECLARE
RESULT BOOLEAN;
BEGIN
IF (NOT DBMS_XDB.existsResource('/public/mysource')) THEN
result := DBMS_XDB.createFolder('/public/mysource');
END IF;
IF (NOT DBMS_XDB.existsResource('/public/mysource/schemas')) THEN
result := DBMS_XDB.createFolder('/public/mysource/schemas');
END IF;
IF (NOT DBMS_XDB.existsResource('/public/mysource/schemas/poSource')) THEN
result := DBMS_XDB.createFolder('/public/mysource/schemas/poSource');
END IF;
IF (NOT DBMS_XDB.existsResource('/public/mysource/schemas/poSource/xsd')) THEN
result := DBMS_XDB.createFolder('/public/mysource/schemas/poSource/xsd');
END IF;
IF (NOT DBMS_XDB.existsResource('/public/mysource/schemas/poSource/xsl')) THEN
result := DBMS_XDB.createFolder('/public/mysource/schemas/poSource/xsl');
END IF;
END;
/

Accessing the Content of Documents using SQL
You can access the content of documents stored in Oracle XML DB Repository in
several ways. The easiest way is to use XDBURIType. XDBURIType uses a URL to
specify which resource to access. The URL passed to the XDBURIType is assumed to
start at the root of the repository. Data type XDBURIType provides methods
getBLOB(), getCLOB(), and getXML() to access the different kinds of content that
can be associated with a resource.
Example 3–52 shows how to use XDBURIType to access the content of the text
document:

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Example 3–52

Accessing a Text Document in the Repository using XDBURITYPE

SELECT XDBURIType('/home/QUINE/NurseryRhyme.txt').getCLOB() FROM DUAL;
XDBURITYPE('/HOME/QUINE/NURSERYRHYME.TXT').GETCLOB()
---------------------------------------------------Mary had a little lamb
Its fleece was white as snow
and everywhere that Mary went
that lamb was sure to go
1 row selected.

The contents of a document can also be accessed using the resource document.
Example 3–53 shows how to access the content of a text document:
Example 3–53

Accessing Resource Content using RESOURCE_VIEW

SELECT CONTENT
FROM RESOURCE_VIEW,
XMLTable(XMLNAMESPACES (default 'http://xmlns.oracle.com/xdb/XDBResource.xsd'),
'/Resource/Contents' PASSING RES
COLUMNS content CLOB PATH 'text')
WHERE equals_path(RES, '/home/QUINE/NurseryRhyme.txt') = 1;
CONTENT
------Mary had a little lamb
Its fleece was white as snow
and everywhere that Mary went
that lamb was sure to go
1 row selected.

The content of non-schema-based and schema-based XML documents can also be
accessed through a resource. Example 3–54 shows how to use an XPath expression that
includes nodes from a resource document and nodes from an XML document to access
the contents of a PurchaseOrder document using the resource.
Example 3–54

Accessing XML Documents using Resource and Namespace Prefixes

SELECT des.description
FROM RESOURCE_VIEW rv,
XMLTable(XMLNAMESPACES ('http://xmlns.oracle.com/xdb/XDBResource.xsd' AS "r"),
'/r:Resource/r:Contents/PurchaseOrder/LineItems/LineItem'
PASSING rv.RES
COLUMNS description VARCHAR2(256) PATH 'Description') des
WHERE
equals_path(rv.RES, '/home/QUINE/PurchaseOrders/2002/Mar/SBELL-2002100912333601PDT.xml') = 1;
DES.DESCRIPTION
--------------------------------A Night to Remember
The Unbearable Lightness Of Being
The Wizard of Oz
3 rows selected.

In Example 3–54, the namespace prefix, r identifies which nodes in the XPath
expression are members of the resource namespace. Namespace prefix r is defined

Using Oracle XML DB 3-75

Using Oracle XML DB Repository

using the XMLNAMESPACES clause of SQL/XML function XMLTable. The namespace
declaration is needed here because the purchase-order XML schema does not define a
namespace, and it is not possible to apply a namespace prefix to nodes in the
PurchaseOrder document.
See Also: Chapter 5, "Using XQuery with Oracle XML DB" for more
information about the XMLNAMESPACES clause of XMLTable

Accessing the Content of XML Schema-Based Documents
The content of a schema-based XML document can be accessed in two ways.
■

■

In the same manner as for non-schema-based XML documents, by using the
resource document. This lets RESOURCE_VIEW be used to query different types of
schema-based XML documents with a single SQL statement.
As a row in the default table that was defined when the XML schema was
registered with Oracle XML DB.

Accessing Resource Content using Element XMLRef in Joins
The XMLRef element in the resource document provides the join key required when a
SQL statement needs to access or update metadata and content as part of a single
operation.
The following queries use joins based on the value of element XMLRef to access
resource content.
Example 3–55 locates a row in the defaultTable based on a path in Oracle XML DB
Repository. SQL function ref locates the target row in the default table, based on the
value of the XMLRef element in the resource document, RES.
Example 3–55

Querying Repository Resource Data using SQL Function REF and Element XMLRef

SELECT des.description
FROM RESOURCE_VIEW rv,
purchaseorder p,
XMLTable('$p/PurchaseOrder/LineItems/LineItem' PASSING p.OBJECT_VALUE AS "p"
COLUMNS description VARCHAR2(256) PATH 'Description') des
WHERE equals_path(rv.RES, '/home/QUINE/PurchaseOrders/2002/Mar/SBELL-2002100912333601PDT.xml')
= 1
AND ref(p) = XMLCast(XMLQuery('declare default element namespace
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
fn:data(/Resource/XMLRef)' PASSING rv.RES RETURNING CONTENT)
AS REF XMLType);
DES.DESCRIPTION
--------------------------------A Night to Remember
The Unbearable Lightness Of Being
The Wizard of Oz
3 rows selected.

Example 3–56 shows how to select fragments from XML documents based on
metadata, path, and content. The query returns the value of element Reference for
documents under /home/QUINE/PurchaseOrders/2002/Mar that contain orders
for part number 715515009058.

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Example 3–56
Content

Selecting XML Document Fragments Based on Metadata, Path, and

SELECT XMLCast(XMLQuery('$p/PurchaseOrder/Reference'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(30))
FROM RESOURCE_VIEW rv, purchaseorder po
WHERE under_path(rv.RES, '/home/QUINE/PurchaseOrders/2002/Mar') = 1
AND ref(po) = XMLCast(
XMLQuery('declare default element namespace
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
fn:data(/Resource/XMLRef)'
PASSING rv.RES RETURNING CONTENT)
AS REF XMLType)
AND XMLExists('$p/PurchaseOrder/LineItems/LineItem/Part[@Id="715515009058"]'
PASSING po.OBJECT_VALUE AS "p");
XMLCAST(XMLQUERY('$P/PURCHASEO
-----------------------------CJOHNSON-20021009123335851PDT
LSMITH-2002100912333661PDT
SBELL-2002100912333601PDT
3 rows selected.

In general, when accessing the content of schema-based XML documents, joining
RESOURCE_VIEW or PATH_VIEW with the default table is more efficient than using
RESOURCE_VIEW or PATH_VIEW on its own. An explicit join between the resource
document and the default table tells Oracle XML DB that the SQL statement works on
only one type of XML document. XPath rewrite can thus be used to optimize
operations on the default table and the resource.

Updating the Content of Documents Stored in the Repository
You can update the content of documents stored in Oracle XML DB Repository using
protocols or SQL.

Updating Repository Content using Protocols
The most popular content authoring tools support HTTP, FTP, and WebDAV protocols.
These tools can use a URL and the HTTP verb get to access the content of a
document, and the HTTP verb put to save the contents of a document. Hence, given
the appropriate access permissions, a simple URL is all you need to access and edit
content stored in Oracle XML DB Repository.
Figure 3–6 shows how, with the WebDAV support included in Microsoft Word, you
can use Microsoft Word to update and edit a document stored in Oracle XML DB
Repository.

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Using Oracle XML DB Repository

Figure 3–6 Updating and Editing Content Stored in Oracle XML DB using Microsoft Word

When an editing application such as Microsoft Word updates an XML document that
is stored in Oracle XML DB, the database receives an input stream containing the new
content of the document. Unfortunately, applications such as Word do not provide
Oracle XML DB with any way of identifying which changes have taken place in the
document.Partial updates are thus impossible. It is necessary to parse the entire
document again, replacing all of the objects derived from the original document with
objects derived from the new content.

Updating Repository Content using SQL
SQL functions such as updateXML can be used to update the content of any document
stored in Oracle XML DB Repository. The content of the document can be modified by
updating the resource document or by updating the default table that holds the
content of the document.
Example 3–57 shows how to update the contents of a simple text document using a
SQL UPDATE statement and SQL function updateXML on the resource document. An
XPath expression is passed to updateXML as the target of the update operation,
identifying the text node belonging to element /Resource/Contents/text.
Example 3–57

Updating a Document using UPDATE and UPDATEXML on the Resource

DECLARE
file
contents
dest_offset

BFILE;
CLOB;
NUMBER := 1;

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src_offset
NUMBER := 1;
lang_context NUMBER := 0;
conv_warning NUMBER := 0;
BEGIN
file := bfilename('XMLDIR', 'tdadxdb-03-02.txt');
DBMS_LOB.createTemporary(contents, true, DBMS_LOB.SESSION);
DBMS_LOB.fileopen(file, DBMS_LOB.file_readonly);
DBMS_LOB.loadClobfromFile(contents,
file,
DBMS_LOB.getLength(file),
dest_offset,
src_offset,
nls_charset_id('AL32UTF8'),
lang_context,
conv_warning);
DBMS_LOB.fileclose(file);
UPDATE RESOURCE_VIEW
SET res = updateXML(res,
'/Resource/Contents/text/text()',
contents,
'xmlns="http://xmlns.oracle.com/xdb/XDBResource.xsd"')
WHERE equals_path(res, '/home/QUINE/NurseryRhyme.txt') = 1;
DBMS_LOB.freeTemporary(contents);
END;
/

This technique for updating the content of a document by updating the associated
resource has the advantage that it can be used to update any kind of document stored
in Oracle XML DB Repository.
Example 3–58 shows how to update a node in an XML document by performing an
update on the resource document. Here, SQL function updateXML changes the value
of the text node associated with element User.
Example 3–58

Updating a Node using UPDATE and UPDATEXML

UPDATE RESOURCE_VIEW
SET res = updateXML(res,
'/r:Resource/r:Contents/PurchaseOrder/User/text()',
'SKING',
'xmlns:r="http://xmlns.oracle.com/xdb/XDBResource.xsd"')
WHERE equals_path(
res,
'/home/QUINE/PurchaseOrders/2002/Mar/SBELL-2002100912333601PDT.xml')
= 1;
1 row updated.
SELECT XMLCast(XMLQuery(
'declare namespace ns="http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
$r/ns:Resource/ns:Contents/PurchaseOrder/User/text()'
PASSING RES AS "r" RETURNING CONTENT)
AS VARCHAR2(32))
FROM RESOURCE_VIEW
WHERE equals_path(RES,
'/home/QUINE/PurchaseOrders/2002/Mar/SBELL-2002100912333601PDT.xml')
= 1;
XMLCAST(XMLQUERY('DECLARENAMESPA
--------------------------------

Using Oracle XML DB 3-79

Using Oracle XML DB Repository

SKING
1 row selected.

Updating XML Schema-Based Documents in the Repository
You can update XML schema-based XML documents by performing the update
operation directly on the default table that is used to manage the content of the
document. If the document must be located by a WHERE clause that includes a path or
conditions based on metadata, then the UPDATE statement must use a join between the
resource and the default table.
In general, when updating the contents of XML schema-based XML documents,
joining the RESOURCE_VIEW or PATH_VIEW with the default table is more efficient
than using the RESOURCE_VIEW or PATH_VIEW on its own. The explicit join between
the resource document and the default table tells Oracle XML DB that the SQL
statement works on only one type of XML document. This lets a partial update be
used on the default table and resource.
In Example 3–59, SQL function updateXML operates on the default table, with the
target row identified by a path. The row to be updated is identified by a REF. The REF
is identified by a repository path using SQL function equals_path. This limits the
update to the row corresponding to the resource identified by the specified path.
Example 3–59

Updating XML Schema-Based Documents in the Repository

UPDATE purchaseorder p
SET p.OBJECT_VALUE = updateXML(p.OBJECT_VALUE, '/PurchaseOrder/User/text()', 'SBELL')
WHERE ref(p) =
(SELECT XMLCast(XMLQuery('declare default element namespace
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
fn:data(/Resource/XMLRef)' PASSING rv.RES RETURNING CONTENT)
AS REF XMLType)
FROM RESOURCE_VIEW rv
WHERE equals_path(rv.RES,
'/home/QUINE/PurchaseOrders/2002/Mar/SBELL-2002100912333601PDT.xml')
= 1);
SELECT XMLCast(XMLQuery('$p/PurchaseOrder/User/text()'
PASSING p.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(32))
FROM purchaseorder p, RESOURCE_VIEW rv
WHERE ref(p) = XMLCast(XMLQuery('declare default element namespace
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
fn:data(/Resource/XMLRef)' PASSING rv.RES RETURNING CONTENT)
AS REF XMLType)
AND equals_path(rv.RES, '/home/QUINE/PurchaseOrders/2002/Mar/SBELL-2002100912333601PDT.xml')
= 1;
XMLCAST(XMLQUERY('$P/PURCHASEO
-----------------------------SBELL

Controlling Access to Repository Data
You can control access to the resources in Oracle XML DB Repository by using access
control lists (ACLs). An ACL is a list of access control entries (ACEs), each of which
grants or denies a set of privileges to a specific principal. The principal can be a
database user, a database role, an LDAP user, an LDAP group or the special principal
DAV::owner, which refers to the owner of the resource. Each resource in the
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repository is protected by an ACL. The ACL determines what privileges, such as
read-properties and update, a user has on the resource. Each repository
operation includes a check of the ACL to determine if the current user is allowed to
perform the operation.
By default, a new resource inherits the ACL of its parent folder. But you can set the
ACL of a resource using PL/SQL procedure DBMS_XDB.setACL. For more details on
Oracle XML DB resource security, see Chapter 27, "Repository Access Control".
In the following example, the current user is QUINE. The query gives the number of
resources in the folder /public. Assume that there are only two resources in this
folder: f1 and f2. Also assume that the ACL on f1 grants the read-properties
privilege to QUINE while the ACL on f2 does not grant QUINE any privileges. A user
needs the read-properties privilege on a resource for it to be visible to the user.
The result of the query is 1, because only f1 is visible to QUINE.
SELECT count(*) FROM RESOURCE_VIEW r WHERE under_path(r.res, '/public') = 1;
COUNT(*)
-------1

Oracle XML DB Transactional Semantics
When working from SQL, normal transactional behavior is enforced. Multiple calls to
SQL functions such as updateXML can be used within a single logical unit of work.
Changes made through functions like updateXML are not visible to other database
users until the transaction is committed. At any point, ROLLBACK can be used to back
out the set of changes made since the last commit.

Querying Metadata and the Folder Hierarchy
In Oracle XML DB, the system-defined metadata for each resource is preserved as an
XML document. The structure of these resource documents is defined by XML schema
XDBResource.xsd. This schema is registered as a global XML schema at URL
http://xmlns.oracle.com/xdb/XDBResource.xsd.
Oracle XML DB gives you access to metadata and information about the folder
hierarchy using two public views, RESOURCE_VIEW and PATH_VIEW.

RESOURCE_VIEW and PATH_VIEW
RESOURCE_VIEW contains one entry for each file or folder stored in Oracle XML DB
Repository. Column RES of RESOURCE_VIEW contains the resource, an XML document
that manages the metadata properties associated with the resource content. Column
ANY_PATH contains a valid URL that the current user can pass to XDBURIType to
access the resource content. If this content is not binary data, then the resource itself
also contains the content.
Oracle XML DB supports the concept of linking. Linking makes it possible to define
multiple paths to a given document. A separate XML document, called the
link-properties document, maintains metadata properties that are specific to the path,
rather than to the resource. Whenever a resource is created, an initial link is also
created.
PATH_VIEW exposes the link-properties documents. There is one entry in PATH_VIEW
for each possible path to a document. Column RES of PATH_VIEW contains the
resource document pointed to by this link. Column PATH contains the path that the

Using Oracle XML DB 3-81

Using Oracle XML DB Repository

link lets you use to access the resource. Column LINK contains the link-properties
document (metadata) for this PATH.
Example 3–60 shows the description of public views RESOURCE_VIEW and PATH_
VIEW:
Example 3–60

Viewing RESOURCE_VIEW and PATH_VIEW Structures

DESCRIBE RESOURCE_VIEW
Name
Null?
Type
------------------------------------------------------------RES
SYS.XMLTYPE(XMLSchema
"http://xmlns.oracle.com/xdb/XDBResource.xsd"
Element
"Resource")
ANY_PATH
VARCHAR2(4000)
RESID
RAW(16)

DESCRIBE PATH_VIEW
Name
Null?
Type
------------------------------------------------------------PATH
VARCHAR2(1024)
RES
SYS.XMLTYPE(XMLSchema
"http://xmlns.oracle.com/xdb/XDBResource.xsd"
Element
"Resource")
LINK
SYS.XMLTYPE
RESID
RAW(16)

See Also:
■

■

■

Chapter 25, "Accessing the Repository using RESOURCE_
VIEW and PATH_VIEW"
Oracle Database Reference for more information about view
PATH_VIEW
Oracle Database Reference for more information about view
RESOURCE_VIEW

Querying Resources in RESOURCE_VIEW and PATH_VIEW
Oracle XML DB provides two SQL functions, equals_path and under_path, that
can be used to perform folder-restricted queries. Such queries limit SQL statements
that operate on the RESOURCE_VIEW or PATH_VIEW to documents that are at a
particular location in Oracle XML DB folder hierarchy. Function equals_path
restricts the statement to a single document identified by the specified path. Function
under_path restricts the statement to those documents that exist beneath a certain
point in the hierarchy.
The following examples demonstrate simple folder-restricted queries against resource
documents stored in RESOURCE_VIEW and PATH_VIEW.
The query in Example 3–61 uses SQL function equals_path and RESOURCE_VIEW to
access the resource created in Example 3–60.

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Example 3–61

Accessing Resources using EQUALS_PATH and RESOURCE_VIEW

SELECT XMLSerialize(DOCUMENT r.res AS CLOB)
FROM RESOURCE_VIEW r
WHERE equals_path(res, '/home/QUINE/NurseryRhyme.txt') = 1;
XMLSERIALIZE(DOCUMENTR.RESASCLOB)
-------------------------------------------------------------------------------
1 row selected.

As Example 3–61 shows, a resource document is an XML document that captures the
set of metadata defined by the DAV standard. The metadata includes information such
as CreationDate, Creator, Owner, ModificationDate, and DisplayName. The
content of the resource document can be queried and updated just like any other XML
document, using SQL/XML access and query functions.

Using Oracle XML DB 3-83

Using Oracle XML DB Repository

The query in Example 3–62 finds a path to each of the XSL style sheets stored in Oracle
XML DB Repository. It performs a search based on the DisplayName ending in .xsl.
Example 3–62

Determining the Path to XSL Style Sheets Stored in the Repository

SELECT ANY_PATH FROM RESOURCE_VIEW
WHERE XMLCast(XMLQuery(
'declare namespace ns="http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
$r/ns:Resource/ns:DisplayName'
PASSING RES AS "r" RETURNING CONTENT)
AS VARCHAR2(100))
LIKE '%.xsl';
ANY_PATH
------------------------------------------/source/schemas/poSource/xsl/empdept.xsl
/source/schemas/poSource/xsl/purchaseOrder.xsl
2 rows selected.

The query in Example 3–63 counts the number of resources (files and folders) under
the path /home/QUINE/PurchaseOrders. Using RESOURCE_VIEW rather than
PATH_VIEW ensures that any resources that are the target of multiple links are only
counted once. SQL function under_path restricts the result set to documents that
can be accessed using a path that starts from /home/QUINE/PurchaseOrders.
Example 3–63

Counting Resources Under a Path

SELECT count(*)
FROM RESOURCE_VIEW
WHERE under_path(RES, '/home/QUINE/PurchaseOrders') = 1;
COUNT(*)
---------145
1 row selected.

The query in Example 3–64 lists the contents of the folder identified by path
/home/QUINE/PurchaseOrders/2002/Apr. This is effectively a directory listing of
the folder.
Example 3–64

Listing the Folder Contents in a Path

SELECT PATH
FROM PATH_VIEW
WHERE under_path(RES, '/home/QUINE/PurchaseOrders/2002/Apr') = 1;
PATH
---------------------------------------------------------------------/home/QUINE/PurchaseOrders/2002/Apr/AMCEWEN-20021009123336171PDT.xml
/home/QUINE/PurchaseOrders/2002/Apr/AMCEWEN-20021009123336271PDT.xml
/home/QUINE/PurchaseOrders/2002/Apr/EABEL-20021009123336251PDT.xml
/home/QUINE/PurchaseOrders/2002/Apr/PTUCKER-20021009123336191PDT.xml
/home/QUINE/PurchaseOrders/2002/Apr/PTUCKER-20021009123336291PDT.xml
/home/QUINE/PurchaseOrders/2002/Apr/SBELL-20021009123336231PDT.xml
/home/QUINE/PurchaseOrders/2002/Apr/SBELL-20021009123336331PDT.xml
/home/QUINE/PurchaseOrders/2002/Apr/SKING-20021009123336321PDT.xml
/home/QUINE/PurchaseOrders/2002/Apr/SMCCAIN-20021009123336151PDT.xml
/home/QUINE/PurchaseOrders/2002/Apr/SMCCAIN-20021009123336341PDT.xml

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/home/QUINE/PurchaseOrders/2002/Apr/VJONES-20021009123336301PDT.xml
11 rows selected.

The query in Example 3–65 lists the set of links contained in the folder identified by
the path /home/QUINE/PurchaseOrders/2002/Apr where the DisplayName
element in the associated resource starts with S.
Example 3–65

Listing the Links Contained in a Folder

SELECT PATH
FROM PATH_VIEW
WHERE XMLCast(XMLQuery(
'declare namespace ns="http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
$r/ns:Resource/ns:DisplayName'
PASSING RES AS "r" RETURNING CONTENT)
AS VARCHAR2(100))
LIKE 'S%'
AND under_path(RES, '/home/QUINE/PurchaseOrders/2002/Apr') = 1;
PATH
---------------------------------------------------------------------/home/QUINE/PurchaseOrders/2002/Apr/SBELL-20021009123336231PDT.xml
/home/QUINE/PurchaseOrders/2002/Apr/SBELL-20021009123336331PDT.xml
/home/QUINE/PurchaseOrders/2002/Apr/SKING-20021009123336321PDT.xml
/home/QUINE/PurchaseOrders/2002/Apr/SMCCAIN-20021009123336151PDT.xml
/home/QUINE/PurchaseOrders/2002/Apr/SMCCAIN-20021009123336341PDT.xml
5 rows selected.

The query in Example 3–66 finds a path to each resource in Oracle XML DB Repository
that contains a PurchaseOrder document. The documents are identified based on
the metadata property SchemaElement that identifies the XML schema URL and
global element for schema-based XML data stored in the repository.
Example 3–66

Finding Paths to Resources that Contain Purchase-Order XML Documents

SELECT ANY_PATH
FROM RESOURCE_VIEW
WHERE XMLExists(
'declare namespace ns="http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
$r/ns:Resource[ns:SchemaElement=
"http://localhost:8080/source/schemas/poSource/xsd/purchaseOrder.xsd#PurchaseOrder"]'
PASSING RES AS "r");

The query returns the following paths, each of which contains a PurchaseOrder
document:
ANY_PATH
----------------------------------------------------------------------/home/QUINE/PurchaseOrders/2002/Apr/AMCEWEN-20021009123336171PDT.xml
/home/QUINE/PurchaseOrders/2002/Apr/AMCEWEN-20021009123336271PDT.xml
/home/QUINE/PurchaseOrders/2002/Apr/EABEL-20021009123336251PDT.xml
/home/QUINE/PurchaseOrders/2002/Apr/PTUCKER-20021009123336191PDT.xml
...
132 rows selected.

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Using Oracle XML DB Repository

Oracle XML DB Hierarchical Repository Index
In a conventional relational database, path-based access and folder-restricted queries
are implemented using CONNECT BY operations. Such queries are expensive, so
path-based access and folder-restricted queries would become inefficient as the
number of documents and depth of the folder hierarchy increase.
To address this issue, Oracle XML DB introduces a new index type, the hierarchical
repository index. This lets the database resolve folder-restricted queries without
relying on a CONNECT BY operation. Because of this, Oracle XML DB can execute
path-based and folder-restricted queries efficiently. The hierarchical repository index is
implemented as an Oracle domain index. This is the same technique used to add
Oracle Text indexing support and many other advanced index types to the database.
Example 3–67 shows the execution plan output generated for a folder-restricted query.
As shown, the hierarchical repository index XDBHI_IDX is used to resolve the query.
Example 3–67

Execution Plan Output for a Folder-Restricted Query

SELECT PATH
FROM PATH_VIEW
WHERE XMLCast(
XMLQuery(
'declare namespace ns="http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
$r/ns:Resource/ns:DisplayName'
PASSING RES AS "r" RETURNING CONTENT)
AS VARCHAR2(100))
LIKE 'S%'
AND under_path(RES, '/home/QUINE/PurchaseOrders/2002/Apr') = 1;
PLAN_TABLE_OUTPUT
-----------------------------------------------------------------------------------------------------Plan hash value: 2568289845
-----------------------------------------------------------------------------------------------------| Id | Operation
| Name
| Rows | Bytes | Cost (%CPU)| Time
|
-----------------------------------------------------------------------------------------------------|
0 | SELECT STATEMENT
|
|
17 | 3111 |
34
(6)| 00:00:01 |
|
1 | NESTED LOOPS
|
|
17 | 3111 |
34
(6)| 00:00:01 |
|
2 |
NESTED LOOPS
|
|
17 | 2822 |
34
(6)| 00:00:01 |
|
3 |
NESTED LOOPS
|
|
466 | 63842 |
34
(6)| 00:00:01 |
|* 4 |
TABLE ACCESS BY INDEX ROWID
| XDB$RESOURCE |
1 |
135 |
3
(0)| 00:00:01 |
|* 5 |
DOMAIN INDEX
| XDBHI_IDX
|
|
|
|
|
|
6 |
COLLECTION ITERATOR PICKLER FETCH|
|
|
|
|
|
|* 7 |
INDEX UNIQUE SCAN
| XDB_PK_H_LINK |
1 |
28 |
0
(0)| 00:00:01 |
|* 8 |
INDEX UNIQUE SCAN
| SYS_C003900
|
1 |
17 |
0
(0)| 00:00:01 |
-----------------------------------------------------------------------------------------------------Predicate Information (identified by operation id):
--------------------------------------------------4 - filter(CAST("P"."SYS_NC00011$" AS VARCHAR2(100)) LIKE 'S%')
5 - access("XDB"."UNDER_PATH"(SYS_MAKEXML('8758D485E6004793E034080020B242C6',734,"XMLEXTRA"
,"XMLDATA"),'/home/QUINE/PurchaseOrders/2002/Apr',9999)=1)
7 - access("H"."PARENT_OID"=SYS_OP_ATG(VALUE(KOKBF$),3,4,2) AND
"H"."NAME"=SYS_OP_ATG(VALUE(KOKBF$),2,3,2))
8 - access("R2"."SYS_NC_OID$"=SYS_OP_ATG(VALUE(KOKBF$),3,4,2))
25 rows selected.

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How Documents are Stored in the Repository
Oracle XML DB provides special handling for XML documents. The rules for storing
the contents of schema-based XML document are defined by the XML schema. The
content of the document is stored in the default table associated with the global
element definition.
Oracle XML DB Repository also stores files that do not contain XML data, such as
JPEG images or Word documents. The XML schema for each resource defines which
elements are allowed, and specifies whether the content of these files is to be stored as
BLOB or CLOB instances. The content of a non-schema-based XML document is stored
as a CLOB instance in the repository.
There is one resource and one link-properties document for each file or folder in the
repository. If there are multiple access paths to a given document, there is a
link-properties document for each possible link. Both the resource document and the
link-properties are stored as XML documents. All these documents are stored in tables
in the repository.
When an XML file is loaded into the repository, the following sequence of events takes
place:
1.

Oracle XML DB examines the root element of the XML document to see if it is
associated with a known (registered) XML schema. This involves looking to see if
the document includes a namespace declaration for the XMLSchema-instance
namespace, and then looking for a schemaLocation or
noNamespaceSchemaLocation attribute that identifies which XML schema the
document is associated with.

2.

If the document is based on a known XML schema, then the metadata for the XML
schema is loaded from the XML schema cache.

3.

The XML document is parsed and decomposed into a set of SQL objects derived
from the XML schema.

4.

The SQL objects created from the XML file are stored in the default table defined
when the XML schema was registered with the database.

5.

A resource document is created for each document processed. This lets the content
of the document be accessed using the repository. The resource document for an
XML schema-based XMLType instance includes an XMLRef element. This element
contains a REF of XMLType that can be used to locate the row in the default table
containing the content associated with the resource.

Viewing Relational Data as XML From a Browser
The HTTP server built into Oracle XML DB makes it possible to use a browser to
access any document stored in Oracle XML DB Repository. Since a resource can
include a REF to a row in an XMLType table or view, it is possible to use a path to
access this type of content.

Accessing a Table or View from a Browser using DBUri SERVLET
Oracle XML DB includes the DBUri servlet, which makes it possible to access the
content of any table or view directly from a browser. DBUri servlet uses the facilities of
the DBURIType to generate a simple XML document from the contents of the table.
The servlet is C language-based and installed in the Oracle XML DB HTTP server. By
default, the servlet is installed under the virtual directory /oradb.

Using Oracle XML DB 3-87

XSL Transformation using DBUri Servlet

The URL passed to the DBUri Servlet is an extension of the URL passed to the
DBURIType. The URL is extended with the address and port number of the Oracle
XML DB HTTP server and the virtual root that directs HTTP(S) requests to the DBUri
servlet. The default configuration for this is /oradb.
The URL http://localhost:8080/oradb/HR/DEPARTMENTS would thus return
an XML document containing the contents of the DEPARTMENTS table in the HR
database schema. This assumes that the Oracle XML DB HTTP server is running on
port 8080, the virtual root for the DBUri servlet is /oradb, and that the user making
the request has access to the HR database schema.
DBUri servlet accepts parameters that allow you to specify the name of the ROW tag
and MIME-type of the document that is returned to the client.
Content in XMLType table or view can also be accessed through the DBUri servlet.
When the URL passed to the DBUri servlet references an XMLType table or XMLType
view the URL can be extended with an XPath expression that can determine which
documents in the table or row are returned. The XPath expression appended to the
URL can reference any node in the document.
XML generated by DBUri servlet can be transformed using the XSLT processor built
into Oracle XML DB. This lets XML that is generated by DBUri servlet be presented in
a more legible format such as HTML.
See Also:

"DBUriServlet" on page 20-26

Style sheet processing is initiated by specifying a transform parameter as part of the
URL passed to DBUri servlet. The style sheet is specified using a URI that references
the location of the style sheet within database. The URI can either be a DBURIType
value that identifies a XMLType column in a table or view, or a path to a document
stored in Oracle XML DB Repository. The style sheet is applied directly to the
generated XML before it is returned to the client. When using DBUri servlet for XSLT
processing, it is good practice to use the contenttype parameter to explicitly specify
the MIME type of the generated output.
If the XML document being transformed is stored as an XML schema-based XMLType
instance, then Oracle XML DB can reduce the overhead associated with XSL
transformation by leveraging the capabilities of the lazily loaded virtual DOM.
The root of the URL is /oradb, so the URL is passed to the DBUri servlet that accesses
the purchaseorder table in the SCOTT database schema, rather than as a resource in
Oracle XML DB Repository. The URL includes an XPath expression that restricts the
result set to those documents where node /PurchaseOrder/Reference/text()
contains the value specified in the predicate. The contenttype parameter sets the
MIME type of the generated document to text/xml.

XSL Transformation using DBUri Servlet
Figure 3–7 shows how an XSL transformation can be applied to XML content
generated by the DBUri servlet. In this example the URL passed to the DBUri includes
the transform parameter. This causes the DBUri servlet to use Oracle SQL function
XMLtransform to apply the style sheet /home/SCOTT/xsl/purchaseOrder.xsl
to the PurchaseOrder document identified by the main URL, before returning the
document to the browser. This style sheet transforms the XML document to a more
user-friendly HTML page. The URL also uses contentType parameter to specify that
the MIME-type of the final document is text/html.

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XSL Transformation using DBUri Servlet

Figure 3–7 Database XSL Transformation of a PurchaseOrder using DBUri Servlet

Figure 3–8 shows the departments table displayed as an HTML document. You need
no code to achieve this, you only need an XMLType view, based on SQL/XML
functions, an industry-standard XSL style sheet, and DBUri servlet.

Using Oracle XML DB 3-89

XSL Transformation using DBUri Servlet

Figure 3–8 Database XSL Transformation of Departments Table using DBUri Servlet

3-90 Oracle XML DB Developer's Guide

Part II
Storing and Retrieving XML Data in Oracle
XML DB
Part II of this manual introduces you to ways you can store, retrieve, validate, and
transform XML data using Oracle XML DB. It contains the following chapters:
■

Chapter 4, "XMLType Operations"

■

Chapter 5, "Using XQuery with Oracle XML DB"

■

Chapter 6, "Indexing XMLType Data"

■

Chapter 7, "XML Schema Storage and Query: Basic"

■

Chapter 8, "XPath Rewrite for Structured Storage"

■

Chapter 9, "XML Schema Storage and Query: Advanced"

■

Chapter 10, "XML Schema Evolution"

■

Chapter 11, "Transforming and Validating XMLType Data"

■

Chapter 12, "Full-Text Search Over XML Data"

4
XMLType Operations
This chapter describes XMLType operations for XML applications (XML schema-based
and non-schema-based). It includes guidelines for creating, manipulating, updating,
and querying XMLType columns and tables.
This chapter contains these topics:
■

Selecting and Querying XML Data

■

Updating XML Data
See Also:
■

■

Chapter 3, "Using Oracle XML DB" for XMLType storage
recommendations
Chapter 7, "XML Schema Storage and Query: Basic" for how to
work with XML schema-based XMLType tables and columns

Selecting and Querying XML Data
You can query XML data from XMLType columns in the following ways:
■

Select XMLType columns using SQL, PL/SQL, or Java.

■

Use the XQuery language. See "Using XQuery with XMLType Data" on page 5-23.

■

■

Query XMLType columns directly or using SQL/XML functions such as
XMLQuery.
Use Oracle Text operators for full-text search. See Chapter 6, "Indexing XMLType
Data" and Chapter 12, "Full-Text Search Over XML Data".

Searching XML Documents using XPath Expressions
The XPath language is a W3C Recommendation for navigating XML documents. It is a
subset of the XQuery language, in the sense that an XPath expression is also an
XQuery expression.
XPath models an XML document as a tree of nodes. It provides a rich set of operations
that walk this tree and apply predicates and node-test functions. Applying an XPath
expression to an XML document can result in a set of nodes. For example, the
expression /PO/PONO selects all PONO child elements under the PO root element of the
document.

XMLType Operations 4-1

Selecting and Querying XML Data

Oracle SQL functions and XMLType methods respect the W3C
XPath recommendation, which states that if an XPath expression
targets no nodes when applied to XML data, then an empty sequence
must be returned. An error must not be raised in this case.

Note:

The specific semantics of an Oracle SQL function or XMLType method
that applies an XPath expression to XML data determines what is
returned. For example, SQL/XML function XMLQuery returns NULL if
its XPath-expression argument targets no nodes, and the updating
SQL functions, such as deleteXML, return the input XML data
unchanged. An error is never raised if no nodes are targeted, but
updating SQL functions can raise an error if an XPath-expression
argument targets inappropriate nodes, such as attribute nodes or text
nodes.
Table 4–1 lists some common constructs used in XPath.
Table 4–1

Common XPath Constructs

XPath Construct

Description

/

Denotes the root of the tree in an XPath expression. For example, /PO refers to the
child of the root node whose name is PO.

/

Also used as a path separator to identify the children node of any given node. For
example, /PurchaseOrder/Reference identifies the purchase-order name element
Reference, a child of the root element.

//

Used to identify all descendants of the current node. For example,
PurchaseOrder//ShippingInstructions matches any
ShippingInstructions element under the PurchaseOrder element.

*

Used as a wildcard to match any child node. For example, /PO/*/STREET matches
any street element that is a grandchild of the PO element.

[ ]

Used to denote predicate expressions. XPath supports a rich list of binary operators
such as or, and, and not. For example, /PO[PONO = 20 and PNAME = "PO_
2"]/SHIPADDR selects the shipping address element of all purchase orders whose
purchase-order number is 20 and whose purchase-order name is PO_2.
Brackets are also used to denote a position (index). For example, /PO/PONO[2]
identifies the second purchase-order number element under the PO root element.

Functions

XPath and XQuery support a set of built-in functions such as substring, round, and
not. In addition, these languages provide for extension functions through the use of
namespaces. Oracle XQuery extension functions use the namespace prefix ora, for
namespace http://xmlns.oracle.com/xdb. See "Oracle XQuery Extension
Functions" on page 5-11.

The XPath must identify a single node, or a set of element, text, or attribute nodes. The
result of the XPath cannot be a Boolean expression.
You can select XMLType data using PL/SQL, C, or Java. You can also use XMLType
method getNumberVal() to retrieve XML data as a NUMBER.

Querying XMLType Data using SQL/XML Functions XMLExists and XMLCast
You can query XMLType data and extract portions of it using SQL/XML standard
functions XMLQuery, XMLTable, XMLExists, and XMLCast.

4-2 Oracle XML DB Developer's Guide

Selecting and Querying XML Data

See Chapter 5, "Using XQuery with Oracle XML DB" for more information about
functions XMLQuery and XMLTable. Functions XMLExists and XMLCast are
described in this section.

XMLEXISTS SQL/XML Function
Figure 4–1 describes the syntax for SQL/XML standard function XMLExists. This
function checks whether a given XQuery expression returns a non-empty XQuery
sequence. If so, the function returns TRUE. Otherwise, it returns FALSE.
Figure 4–1 XMLExists Syntax
XML_passing_clause
XMLEXISTS

(

XQuery_string

)

XML_passing_clause ::=
,
BY
PASSING

■

■

VALUE

AS

identifier

expr

XQuery_string is a complete XQuery expression, possibly including a prolog, as
a literal string. It can contain XQuery variables that you bind using the XQuery
PASSING clause (XML_passing_clause in the syntax diagram). The predefined
namespace prefixes recognized for SQL/XML function XMLQuery are also
recognized in XQuery_string—see "Predefined Namespaces and Prefixes" on
page 5-9.
The XML_passing_clause is the keyword PASSING followed by one or more
SQL expressions (expr) that each return an XMLType instance or an instance of a
SQL scalar data type. All but possibly one of the expressions must each be
followed by the keyword AS and an XQuery identifier. The result of
evaluating each expr is bound to the corresponding identifier for the
evaluation of XQuery_string. If there is an expr that is not followed by an AS
clause, then the result of evaluating that expr is used as the context item for
evaluating XQuery_string. Oracle XML DB supports only passing BY VALUE,
not passing BY REFERENCE, so the clause BY VALUE is implicit and can be
omitted.

If an XQuery expression such as /PurchaseOrder/Reference or
/PurchaseOrder/Reference/text() targets a single node, then XMLExists
returns true for that expression. If XMLExists is called with an XQuery expression
that locates no nodes, then XMLExists returns false.
Function XMLExists can be used in queries, and it can be used to create
function-based indexes to speed up evaluation of queries.
Note: Oracle XML DB limits the use of XMLExists to a SQL WHERE
clause or CASE expression. If you need to use XMLExists in a
SELECT list, then wrap it in a CASE expression:
CASE WHEN XMLExists(...) THEN 'TRUE' ELSE 'FALSE' END

Example 4–1 uses SQL/XML standard function XMLExists to select rows with
SpecialInstructions set to Expedite.

XMLType Operations 4-3

Selecting and Querying XML Data

Example 4–1 Finding a Node using SQL/XML Function XMLExists
SELECT OBJECT_VALUE
FROM purchaseorder
WHERE XMLExists('/PurchaseOrder[SpecialInstructions="Expedite"]'
PASSING OBJECT_VALUE);
OBJECT_VALUE
------------------------------------------------------------------- 0]'
PASSING po.OBJECT_VALUE AS "p")

XMLType Operations 4-9

Updating XML Data

AND XMLCast(XMLQuery('$p/PurchaseOrder/Requestor/text()'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(128))
LIKE '%ll%'
GROUP BY XMLCast(XMLQuery('$p/PurchaseOrder/Requestor'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(128));
NAME
COUNT(*)
-------------------- ---------Allan D. McEwen
9
Ellen S. Abel
4
Sarah J. Bell
13
William M. Smith
7

Example 4–8 uses SQL/XML function XMLQuery to extract nodes identified by an
XPath expression. The XMLType instance returned by XMLQuery can be a set of nodes,
a singleton node, or a text value. Example 4–8 uses XMLType method isFragment()
to determine whether the result is a fragment.
Example 4–8 Extracting Fragments from an XMLTYPE Instance using XMLQUERY
SELECT XMLCast(XMLQuery('$p/PurchaseOrder/Reference' PASSING po.OBJECT_VALUE AS "p"
RETURNING CONTENT)
AS VARCHAR2(30)) reference,
count(*)
FROM purchaseorder po, XMLTable('$p//LineItem[Part/@Id="37429148327"]' PASSING OBJECT_VALUE AS "p")
WHERE XMLQuery('$p/PurchaseOrder/LineItems/LineItem[Part/@Id="37429148327"]'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT).isFragment() = 1
GROUP BY XMLCast(XMLQuery('$p/PurchaseOrder/Reference' PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(30))
ORDER BY XMLCast(XMLQuery('$p/PurchaseOrder/Reference' PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(30));
REFERENCE
COUNT(*)
-------------------------------- ---------TFOX-20021009123337784PDT
3

Note: You cannot insert fragments into XMLType columns. You
can use SQL function sys_XMLGen to convert a fragment into a
well-formed document by adding an enclosing tag. See "SYS_
XMLGEN Oracle SQL Function" on page 18-46.

Updating XML Data
This section covers updating XML data, both transient data and data stored in tables.
It describes the use of the following SQL functions:
■

updateXML

■

insertChildXML

■

insertChildXMLbefore

■

insertChildXMLafter

■

insertXMLbefore

■

insertXMLafter

■

appendChildXML

■

deleteXML

4-10 Oracle XML DB Developer's Guide

Updating XML Data

Updating an Entire XML Document
For unstructured storage (CLOB), an update effectively replaces the entire document.
To update an entire XML document, use a SQL UPDATE statement. The right side of
the UPDATE statement SET clause must be an XMLType instance. This can be created in
any of the following ways:
■
■

■

Use SQL functions or XML constructors that return an XML instance.
Use the PL/SQL DOM APIs for XMLType that change and bind an existing XML
instance.
Use the Java DOM API that changes and binds an existing XML instance.

Updates for non-schema-based XML documents stored as CLOB values (unstructured
storage) always update the entire XML document. Updates for non-schema-based
documents stored as binary XML can be made in a piecewise manner. See "Updating
XML Schema-Based and Non-Schema-Based XML Documents" on page 3-57.
Example 4–9 updates an XMLType instance using a SQL UPDATE statement.
Example 4–9 Updating XMLType Data using a SQL UPDATE Statement
SELECT t.reference, li.lineno, li.description
FROM purchaseorder po,
XMLTable('$p/PurchaseOrder' PASSING po.OBJECT_VALUE AS "p"
COLUMNS reference VARCHAR2(28) PATH 'Reference',
lineitem XMLType
PATH 'LineItems/LineItem') t,
XMLTable('$l/LineItem' PASSING t.lineitem AS "l"
COLUMNS lineno
NUMBER(10)
PATH '@ItemNumber',
description VARCHAR2(128) PATH 'Description') li
WHERE t.reference = 'DAUSTIN-20021009123335811PDT' AND ROWNUM < 6;
REFERENCE
LINENO DESCRIPTION
-------------------------------- ------- ----------------DAUSTIN-20021009123335811PDT
1 Nights of Cabiria
DAUSTIN-20021009123335811PDT
2 For All Mankind
DAUSTIN-20021009123335811PDT
3 Dead Ringers
DAUSTIN-20021009123335811PDT
4 Hearts and Minds
DAUSTIN-20021009123335811PDT
5 Rushmore
UPDATE purchaseorder po
SET po.OBJECT_VALUE = XMLType(bfilename('XMLDIR','NEW-DAUSTIN-20021009123335811PDT.xml'),
nls_charset_id('AL32UTF8'))
WHERE XMLExists('$p/PurchaseOrder[Reference="DAUSTIN-20021009123335811PDT"]'
PASSING po.OBJECT_VALUE AS "p");
SELECT t.reference, li.lineno, li.description
FROM purchaseorder po,
XMLTable('$p/PurchaseOrder' PASSING po.OBJECT_VALUE AS "p"
COLUMNS reference VARCHAR2(28) PATH 'Reference',
lineitem XMLType
PATH 'LineItems/LineItem') t,
XMLTable('$l/LineItem' PASSING t.lineitem AS "l"
COLUMNS lineno
NUMBER(10)
PATH '@ItemNumber',
description VARCHAR2(128) PATH 'Description') li
WHERE t.reference = 'DAUSTIN-20021009123335811PDT';
REFERENCE
LINENO DESCRIPTION
-------------------------------- ------- -------------------------------DAUSTIN-20021009123335811PDT
1 Dead Ringers
DAUSTIN-20021009123335811PDT
2 Getrud
DAUSTIN-20021009123335811PDT
3 Branded to Kill

XMLType Operations 4-11

Updating XML Data

SQL Functions that Update XML Data
There are several Oracle SQL functions that you can use to update XML data
incrementally—that is, to replace, insert, or delete XML data without replacing the
entire surrounding XML document. This is also called partial updating. These Oracle
SQL functions are described in the following sections:
■

■

■

■

■

■

■

■

updateXML – Replace XML nodes of any kind. See "UPDATEXML SQL Function"
on page 4-14.
insertChildXML – Insert XML element or attribute nodes as children of a given
element node. See "INSERTCHILDXML SQL Function" on page 4-23.
insertChildXMLbefore – Insert new collection elements immediately before a
given collection element of the same type. See "INSERTCHILDXMLBEFORE SQL
Function" on page 4-25.
insertChildXMLafter – Insert new collection elements immediately after a
given collection element of the same type. See "INSERTCHILDXMLAFTER SQL
Function" on page 4-26.
insertXMLbefore – Insert XML nodes of any kind immediately before a given
node (other than an attribute node). See "INSERTXMLBEFORE SQL Function" on
page 4-27.
insertXMLafter – Insert XML nodes of any kind immediately after a given
node (other than an attribute node). See "INSERTXMLAFTER SQL Function" on
page 4-29.
appendChildXML – Insert XML nodes of any kind as the last child nodes of a
given element node. See "APPENDCHILDXML SQL Function" on page 4-30.
deleteXML – Delete XML nodes of any kind. See "DELETEXML SQL Function"
on page 4-31.

Use functions insertChildXML, insertChildXMLbefore,
insertChildXMLafter, insertXMLbefore, insertXMLafter, and
appendChildXML to insert XML data. Use function deleteXML to delete XML data.
Use function updateXML to replace XML data.
In particular, do not use function updateXML to insert or delete XML data by replacing
a parent node in its entirety. That works, but it is less efficient than using one of the
other functions, which perform more localized updates.
These Oracle SQL functions do not, by themselves, change database data – they are all
pure functions, without side effect. Each applies an XPath-expression argument to
input XML data and returns a modified copy of the input XML data. You can then use
that result with SQL DML operator UPDATE to modify database data. This is no
different from the way you use SQL function upper to convert database data to
uppercase: you must use a SQL DML operator such as UPDATE to change the stored
data.
Each of these functions can be used on XML documents that are either schema-based
or non-schema-based. For XML schema-based data, these Oracle SQL functions
perform partial validation on the result, and, where appropriate, argument values are
also checked for compatibility with the XML schema.

4-12 Oracle XML DB Developer's Guide

Updating XML Data

Oracle SQL functions and XMLType methods respect the W3C
XPath recommendation, which states that if an XPath expression
targets no nodes when applied to XML data, then an empty sequence
must be returned. An error must not be raised in this case.

Note:

The specific semantics of an Oracle SQL function or XMLType method
that applies an XPath expression to XML data determines what is
returned. For example, SQL/XML function XMLQuery returns NULL if
its XPath-expression argument targets no nodes, and the updating
Oracle SQL functions, such as deleteXML, return the input XML data
unchanged. An error is never raised if no nodes are targeted, but
updating SQL functions can raise an error if an XPath-expression
argument targets inappropriate nodes, such as attribute nodes or text
nodes.
See Also: "Partial Validation" on page 3-32 for more information
about partial validation against an XML schema

Inserting XML Elements using SQL Functions
There are several Oracle SQL functions for inserting XML nodes into (a copy of)
existing XML data. Each can insert nodes at multiple locations that are referenced by
an XPath expression. They differ in the placement of the new nodes and how the target
XML data is referenced.
■

■

■

Function appendChildXML appends nodes to the target elements. That is, for
each target element, it inserts one or more nodes of any kind as the element's last
children.
Function insertChildXML inserts new children (one or more elements of the
same type or a single attribute) under target elements. The position of a new child
element under its parent is not specified. If the target data is XML schema-based,
then the schema can sometimes be used to determine the position. Otherwise, the
position is arbitrary.
Function insertXMLbefore inserts one or more nodes of any kind immediately
before a target node (which is not an attribute node).
Function insertXMLafter inserts a node similarly, but after the target, not
before.

■

Function insertChildXMLbefore is similar to insertChildXML, except that
the inserted node must be an element (not an attribute), and you specify the
position of the new element among its siblings. It is similar to
insertXMLbefore, except that it inserts only collection elements, not arbitrary
elements. The insertion position specifies a successor collection member. The
actual element to be inserted must correspond to the element type for the
collection.
Function insertChildXMLafter inserts a node similarly, but after the target,
not before.

Though the effect of insertChildXMLbefore (-after) is similar to that of
insertXMLbefore (-after), the target location is expressed differently. For the
former, the target is the parent of the new child. For the latter, the target is the
succeeding (or preceding) sibling. This difference is reflected in the function names
(Child).

XMLType Operations 4-13

Updating XML Data

For example, to insert a new LineItem element before the third LineItem element
under element /PurchaseOrder/LineItems, you can use
insertChildXMLbefore, specifying the target parent as
/PurchaseOrder/LineItems and the succeeding sibling as LineItem[3]. Or you
can use insertXMLbefore, specifying the target succeeding sibling as
/PurchaseOrder/LineItems/LineItem[3]. If you use insertChildXML for the
insertion, then you cannot specify the position of the new element in the
collection—the resulting position is indeterminate.
Another difference among these functions is that all of them except
insertXMLbefore, insertXMLafter, and appendChildXML—are optimized for
SQL UPDATE operations on XMLType tables and columns that are stored
object-relationally or as binary XML.
See Also: "Optimization of Oracle SQL Functions that Modify XML
Data" on page 4-20

UPDATEXML SQL Function
Oracle SQL function updateXML replaces XML nodes of any kind. The XML
document that is the target of the update can be schema-based or non-schema-based.
A copy of the input XMLType instance is modified and returned. The original data is
unaffected. You can then use the returned data with SQL operation UPDATE to modify
database data.
Function updateXML has the following parameters (in order):
■

target-data (XMLType) – The XML data containing the target node to replace.

■

One or more pairs of xpath and replacement parameters:

■

–

xpath (VARCHAR2) – An XPath 1.0 expression that locates the nodes within
target-data to replace. Each targeted node is replaced by replacement.
These can be nodes of any kind. If xpath matches an empty sequence of
nodes then no replacement is done, and target-data is returned unchanged
(and no error is raised).

–

replacement (XMLType or VARCHAR2) – The XML data that replaces the
data targeted by xpath. The data type of replacement must correspond to
the data to be replaced. If xpath targets an element node for replacement,
then the data type must be XMLType. If xpath targets an attribute node or a
text node, then it must be VARCHAR2. For an attribute node, replacement is
only the replacement value of the attribute (for example, 23), not the complete
attribute node including the name (for example, my_attribute="23").

namespace (VARCHAR2, optional) – The XML namespace for parameter xpath.

Oracle SQL function updateXML can be used to replace existing elements, attributes,
and other nodes with new values. It is not an efficient way to insert new nodes or
delete existing ones. You can perform insertions and deletions with updateXML only
by using it to replace the entire node that is the parent of the node to be inserted or
deleted.
Function updateXML updates only the transient XML instance in memory. Use a SQL
UPDATE statement to update data stored in tables.
Figure 4–3 illustrates the syntax.

4-14 Oracle XML DB Developer's Guide

Updating XML Data

Figure 4–3 UPDATEXML Syntax
,
UPDATEXML

(

XMLType_instance

,

XPath_string

,
,

namespace_string

value_expr

)

Example 4–10 uses updateXML on the right side of an UPDATE statement to update
the XML document in a table instead of creating a new document. The entire
document is updated, not just the part that is selected.
Example 4–10

Updating XMLTYPE using UPDATE and UPDATEXML

SELECT XMLQuery('$p/PurchaseOrder/Actions/Action[1]' PASSING po.OBJECT_VALUE AS "p"
RETURNING CONTENT) action
FROM purchaseorder po
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING po.OBJECT_VALUE AS "p");
ACTION
-------------------------------
SVOLLMAN

UPDATE purchaseorder po
SET po.OBJECT_VALUE = updateXML(po.OBJECT_VALUE,
'/PurchaseOrder/Actions/Action[1]/User/text()',
'SKING')
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING po.OBJECT_VALUE AS "p");
SELECT XMLQuery('$p/PurchaseOrder/Actions/Action[1]' PASSING po.OBJECT_VALUE AS "p"
RETURNING CONTENT) action
FROM purchaseorder po
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING po.OBJECT_VALUE AS "p");
ACTION
--------------------------------
SKING


Example 4–11 updates multiple nodes using Oracle SQL function updateXML.
Example 4–11

Updating Multiple Text Nodes and Attribute Values using UPDATEXML

SELECT XMLCast(XMLQuery('$p/PurchaseOrder/Requestor'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(30)) name,
XMLQuery('$p/PurchaseOrder/LineItems'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT) lineitems
FROM purchaseorder po
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING po.OBJECT_VALUE AS "p");
NAME
LINEITEMS
---------------- -----------------------------------------------------------------------Sarah J. Bell


A Night to Remember

XMLType Operations 4-15

Updating XML Data




The Unbearable Lightness Of Being



Sisters



UPDATE purchaseorder
SET OBJECT_VALUE = updateXML(OBJECT_VALUE,
'/PurchaseOrder/Requestor/text()','Stephen G. King',
'/PurchaseOrder/LineItems/LineItem[1]/Part/@Id','786936150421',
'/PurchaseOrder/LineItems/LineItem[1]/Description/text()','The Rock',
'/PurchaseOrder/LineItems/LineItem[3]',
XMLType('
Dead Ringers

'))
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
SELECT XMLCast(XMLQuery('$p/PurchaseOrder/Requestor'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(30)) name,
XMLQuery('$p/PurchaseOrder/LineItems'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT) lineitems
FROM purchaseorder po
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING po.OBJECT_VALUE AS "p");
NAME
LINEITEMS
---------------- -----------------------------------------------------------------Stephen G. King 

The Rock



The Unbearable Lightness Of Being



Dead Ringers




Example 4–12 uses SQL function updateXML to update selected nodes within a
collection.
Example 4–12

Updating Selected Nodes within a Collection using UPDATEXML

SELECT XMLCast(XMLQuery('$p/PurchaseOrder/Requestor'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(30)) name,
XMLQuery('$p/PurchaseOrder/LineItems'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT) lineitems
FROM purchaseorder po
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING po.OBJECT_VALUE AS "p");

4-16 Oracle XML DB Developer's Guide

Updating XML Data

NAME
LINEITEMS
---------------- ---------------------------------------------------------------Sarah J. Bell


A Night to Remember



The Unbearable Lightness Of Being



Sisters



UPDATE purchaseorder
SET OBJECT_VALUE =
updateXML(OBJECT_VALUE,
'/PurchaseOrder/Requestor/text()','Stephen G. King',
'/PurchaseOrder/LineItems/LineItem/Part[@Id="715515009058"]/@Quantity',
25,
'/PurchaseOrder/LineItems/LineItem[Description/text() =
"The Unbearable Lightness Of Being"]',
XMLType('

The Rock
'))
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
SELECT XMLCast(XMLQuery('$p/PurchaseOrder/Requestor'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(30)) name,
XMLQuery('$p/PurchaseOrder/LineItems'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT) lineitems
FROM purchaseorder po
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING po.OBJECT_VALUE AS "p");
NAME
LINEITEMS
---------------- ------------------------------------------------------------Stephen G. King 

A Night to Remember




The Rock


Sisters




XMLType Operations 4-17

Updating XML Data

UPDATEXML and NULL Values
■

■

■

If you update an XML element to NULL, the attributes and children of the element
are removed, and the element becomes empty. The type and namespace properties
of the element are retained. See Example 4–13.
If you update an attribute value to NULL, the value appears as the empty string. See
Example 4–13.
If you update the text node of an element to NULL, the content (text) of the element
is removed. The element itself remains, but it is empty. See Example 4–14.

Example 4–13 updates all of the following to NULL:
■

■

Example 4–13

The Description element and the Quantity attribute of the LineItem element
whose Part element has attribute Id value 715515009058.
The LineItem element whose Description element has the content (text) "The
Unbearable Lightness Of Being".

NULL Updates with UPDATEXML – Element and Attribute

SELECT XMLCast(XMLQuery('$p/PurchaseOrder/Requestor'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(30)) name,
XMLQuery('$p/PurchaseOrder/LineItems'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT) lineitems
FROM purchaseorder po
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING po.OBJECT_VALUE AS "p");
NAME
LINEITEMS
---------------- ------------------------------------------------------------------Sarah J. Bell


A Night to Remember



The Unbearable Lightness Of Being



Sisters



UPDATE purchaseorder
SET OBJECT_VALUE =
updateXML(
OBJECT_VALUE,
'/PurchaseOrder/LineItems/LineItem[Part/@Id="715515009058"]/Description', NULL,
'/PurchaseOrder/LineItems/LineItem/Part[@Id="715515009058"]/@Quantity', NULL,
'/PurchaseOrder/LineItems/LineItem[Description/text()=
"The Unbearable Lightness Of Being"]', NULL)
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
SELECT XMLCast(XMLQuery('$p/PurchaseOrder/Requestor'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(30)) name,

4-18 Oracle XML DB Developer's Guide

Updating XML Data

XMLQuery('$p/PurchaseOrder/LineItems'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT) lineitems
FROM purchaseorder po
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING po.OBJECT_VALUE AS "p");
NAME
LINEITEMS
---------------- ---------------------------------------------------------------Sarah J. Bell







Sisters




Example 4–14 updates the text node of a Part element whose Description attribute
has value "A Night to Remember" to NULL. The XML data for this example
corresponds to a different, revised purchase-order XML schema – see "Scenario for
Copy-Based Evolution" on page 10-2. In that XML schema, Description is an
attribute of the Part element, not a sibling element.
Example 4–14

NULL Updates with UPDATEXML – Text Node

SELECT XMLCast(XMLQuery('$p/PurchaseOrder/LineItems/LineItem/Part[@Description="A Night to Remember"]'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(128)) part
FROM purchaseorder po
WHERE XMLExists('$p/PurchaseOrder[@Reference="SBELL-2003030912333601PDT"]'
PASSING po.OBJECT_VALUE AS "p");
PART
---715515009058
UPDATE purchaseorder
SET OBJECT_VALUE =
updateXML(OBJECT_VALUE,
'/PurchaseOrder/LineItems/LineItem/Part[@Description="A Night to Remember"]/text()', NULL)
WHERE XMLExists('$p/PurchaseOrder[@Reference="SBELL-2003030912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
SELECT XMLCast(XMLQuery('$p/PurchaseOrder/LineItems/LineItem/Part[@Description="A Night to Remember"]'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(128)) part
FROM purchaseorder po
WHERE XMLExists('$p/PurchaseOrder[@Reference="SBELL-2003030912333601PDT"]'
PASSING po.OBJECT_VALUE AS "p");
PART
---

See Also: Example 3–36, "Updating XML Content using
UPDATEXML"

XMLType Operations 4-19

Updating XML Data

Updating the Same XML Node More Than Once
You can update the same XML node more than once in an updateXML expression. For
example, you can update both /EMP[EMPNO=217] and
/EMP[EMPNAME="Jane"]/EMPNO, where the first XPath identifies the EMPNO node
containing it as well. The order of updates is determined by the order of the XPath
expressions in left-to-right order. Each successive XPath works on the result of the
previous XPath update.

Preserving DOM Fidelity When using UPDATEXML
Here are some guidelines for preserving DOM fidelity when using Oracle SQL
function updateXML:
When DOM Fidelity is Preserved When you update an element to NULL, you make that
element appear empty in its parent, such as in .
When you update a text node inside an element to NULL, you remove that text node
from the element.
When you update an attribute node to NULL, you make the value of the attribute
become the empty string, for example, myAttr="".
When DOM Fidelity is Not Preserved When you update a complexType element to NULL,
you make the element appear empty in its parent, for example, .
When you update a SQL-inlined simpleType element to NULL, you make the element
disappear from its parent.
When you update a text node to NULL, you are doing the same thing as setting the
parent simpleType element to NULL. Furthermore, text nodes can appear only inside
simpleType elements when DOM fidelity is not preserved, since there is no
positional descriptor with which to store mixed content.
When you update an attribute node to NULL, you remove the attribute from the
element.
Determining Whether DOM Fidelity is Preserved You can determine whether or not DOM
fidelity is preserved for particular parts of a given XMLType in a given XML schema
by querying the schema metadata for attribute maintainDOM.
See Also:
■

■

"Querying a Registered XML Schema to Obtain Annotations"
on page 7-43 for an example of querying a schema to retrieve
DOM fidelity values
"DOM Fidelity" on page 7-16

Optimization of Oracle SQL Functions that Modify XML Data
In most cases, the Oracle SQL functions that modify XML data materialize a copy of
the entire input XML document in memory, then update the copy. However, functions
updateXML, insertChildXML, insertChildXMLbefore,
insertChildXMLafter, and deleteXML—that is, all except insertXMLbefore,
insertXMLafter, and appendChildXML—are optimized for SQL UPDATE
operations on XMLType tables and columns that are stored object-relationally or as
binary XML.
For structured storage, if particular conditions are met, then the function call can be
rewritten to update the object-relational columns directly with the values. For binary
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Updating XML Data

XML storage, data preceding the targeted update is not modified, and, if SecureFile
LOBs are used (the default behavior), then sliding inserts are used to update only the
portions of the data that need changing.
See Also:
■

■

■

"Updating XML Schema-Based and Non-Schema-Based XML
Documents" on page 3-57 for more about piecewise updating
Chapter 3, "Using Oracle XML DB" and Chapter 8, "XPath Rewrite
for Structured Storage" for information about the conditions for
XPath rewrite
"Performance Tuning for XQuery" on page 5-29

As an example with object-relational storage, the XPath argument to updateXML in
Example 4–15 is processed by Oracle XML DB and rewritten into equivalent
object-relational SQL code, as illustrated in Example 4–16.
Example 4–15

XPath Expressions in UPDATEXML Expression

SELECT XMLCast(XMLQuery('$p/PurchaseOrder/User'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(30))
FROM purchaseorder po
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING po.OBJECT_VALUE AS "p");
XMLCAST(XMLQUERY('$P/PURCHASEO
-----------------------------SBELL
UPDATE purchaseorder
SET OBJECT_VALUE = updateXML(OBJECT_VALUE, '/PurchaseOrder/User/text()', 'SVOLLMAN')
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING OBJECT_VALUE AS "p");
SELECT XMLCast(XMLQuery('$p/PurchaseOrder/User'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(30))
FROM purchaseorder po
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING po.OBJECT_VALUE AS "p");
XMLCAST(XMLQUERY('$P/PURCHASEO
-----------------------------SVOLLMAN
Example 4–16

Object Relational Equivalent of UPDATEXML Expression

SELECT XMLCast(XMLQuery('$p/PurchaseOrder/User'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(30))
FROM purchaseorder po
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING po.OBJECT_VALUE AS "p");
XMLCAST(XMLQUERY('$P/PURCHASEO
-----------------------------SBELL

XMLType Operations 4-21

Updating XML Data

UPDATE purchaseorder p
SET p."XMLDATA"."USERID" = 'SVOLLMAN'
WHERE p."XMLDATA"."REFERENCE" = 'SBELL-2002100912333601PDT';
SELECT XMLCast(XMLQuery('$p/PurchaseOrder/User'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(30))
FROM purchaseorder po
WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]'
PASSING po.OBJECT_VALUE AS "p");

XMLCAST(XMLQUERY('$P/PURCHASEO
-----------------------------SVOLLMAN

The use of XMLDATA for DML is shown here only as an
illustration of internal Oracle XML DB behavior. Do not use XMLDATA
yourself for DML operations. You can use XMLDATA directly only for
DDL operations, never for DML operations.

Note:

More generally, in your code, do not rely on the current mapping
between the XML Schema object model and the SQL object model.
This Oracle XML DB implementation mapping might change in the
future.

Creating XML Views using Oracle SQL Functions that Modify XML Data
You can use the Oracle SQL functions that modify XML data (updateXML,
insertChildXML, insertChildXMLbefore, insertChildXMLafter,
insertXMLbefore, insertXMLafter, appendChildXML, and deleteXML) to
create new views of XML data.
Example 4–17 creates a view of table purchaseorder using Oracle SQL function
updateXML.
Example 4–17

Creating a View using UPDATEXML

CREATE OR REPLACE VIEW purchaseorder_summary OF XMLType AS
SELECT updateXML(OBJECT_VALUE,
'/PurchaseOrder/Actions', NULL,
'/PurchaseOrder/ShippingInstructions', NULL,
'/PurchaseOrder/LineItems', NULL) AS XML
FROM purchaseorder p;
SELECT OBJECT_VALUE FROM purchaseorder_summary
WHERE XMLExists('$p/PurchaseOrder[Reference="DAUSTIN-20021009123335811PDT"]'
PASSING OBJECT_VALUE AS "p");
OBJECT_VALUE
--------------------------------------------------------------------------
DAUSTIN-20021009123335811PDT


David L. Austin

4-22 Oracle XML DB Developer's Guide

Updating XML Data

DAUSTIN
S30

Courier



INSERTCHILDXML SQL Function
Oracle SQL function insertChildXML inserts new children (one or more elements of
the same type or a single attribute) under parent XML elements. The XML document
that is the target of the insertion can be schema-based or non-schema-based.
A copy of the input XMLType instance is modified and returned. The original data is
unaffected. You can then use the returned data with SQL operation UPDATE to modify
database data.
Function insertChildXML has the following parameters (in order):
■
■

target-data (XMLType) – The XML data containing the target parent element.
parent-xpath (VARCHAR2) – An XPath 1.0 expression that locates the parent
elements within target-data. The child-data is inserted under each parent
element.
If parent-xpath matches an empty sequence of element nodes, then no insertion
is done, and target-data is returned unchanged (no error is raised). If
parent-xpath does not match a sequence of element nodes (in particular, if
parent-xpath matches one or more attribute or text nodes), then an error is
raised.

■

■

■

child-name (VARCHAR2) – The name of the child elements or attribute to insert.
An attribute name is distinguished from an element name by having an at-sign (@)
prefix as part of child-name, for example, @my_attribute versus my_
element. (The at-sign is not part of the attribute name, but serves in the argument
to indicate that child-name refers to an attribute.)
child-data (XMLType or VARCHAR2) – The child XML data to insert:
–

If one or more elements are being inserted, then this is of data type XMLType,
and it contains element nodes. Each of the top-level element nodes in
child-data must have the same name (tag) as child-name (or else an error
is raised).

–

If an attribute is being inserted, then this is of data type VARCHAR2, and it
represents the (scalar) attribute value. If an attribute of the same name already
exists at the insertion location, then an error is raised.

namespace (VARCHAR2, optional) – The XML namespace for parameters
parent-xpath and child-data.

XML data child-data is inserted as one or more child elements, or a single child
attribute, under each of the parent elements located at parent-xpath.
In order of decreasing precedence, function insertChildXML has the following
behavior for NULL arguments:
■

If child-name is NULL, then an error is raised.

■

If target-data or parent-xpath is NULL, then NULL is returned.

■

If child-data is NULL, then:

XMLType Operations 4-23

Updating XML Data

–

If child-name names an element, then no insertion is done, and
target-data is returned unchanged.

–

If child-name names an attribute, then an empty attribute value is inserted,
for example, my_attribute = "".

Figure 4–4 shows the syntax.
Figure 4–4 INSERTCHILDXML Syntax
INSERTCHILDXML

,
(

XMLType_instance

,

XPath_string

,

child_expr

,

namespace_string

value_expr

)

If target-data is XML schema-based, then the schema is consulted to determine the
insertion positions. For example, if the schema constrains child elements named
child-name to be the first child elements of a parent-xpath, then the insertion
takes this into account. Similarly, if the child-name or child-data argument is
inappropriate for an associated schema, then an error is raised.
If the parent element does not yet have a child corresponding in name and kind to
child-name (and if such a child is permitted by the associated XML schema, if any),
then child-data is inserted as new child elements, or a new attribute value, named
child-name.
If the parent element already has a child attribute named child-name (without the
at-sign), then an error is raised. If the parent element already has a child element named
child-name (and if more than one child element is permitted by the associated XML
schema, if any), then child-data is inserted so that its elements become child
elements named child-name, but their positions in the sequence of children are
unpredictable.
If you need to insert elements into an existing, non-empty collection of child elements,
and the order is important to you, then use SQL/XML function appendChildXML or
insertXMLbefore.
Example 4–18 shows how to use a SQL UPDATE statement and Oracle SQL function
insertChildXML to insert a new LineItem element as a child of element
LineItems.
Example 4–18

Inserting a LineItem Element into a LineItems Element

SELECT XMLQuery('$p/PurchaseOrder/LineItems/LineItem[@ItemNumber=222]'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
FROM purchaseorder po
WHERE XMLExists('$p/PurchaseOrder[Reference="AMCEWEN-20021009123336171PDT"]'
PASSING po.OBJECT_VALUE AS "p");
XMLQUERY('$P/PURCHASEORDER/LINEITEMS/LINEITEM[@ITEMNUMBER=222]'
--------------------------------------------------------------1 row selected.
UPDATE purchaseorder
SET OBJECT_VALUE =
insertChildXML(OBJECT_VALUE,
'/PurchaseOrder/LineItems',
'LineItem',
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Updating XML Data

XMLType('
The Harder They Come

'))
WHERE XMLExists('$p/PurchaseOrder[Reference="AMCEWEN-20021009123336171PDT"]'
PASSING OBJECT_VALUE AS "p");
SELECT XMLQuery('$p/PurchaseOrder/LineItems/LineItem[@ItemNumber=222]'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
FROM purchaseorder po
WHERE XMLExists('$p/PurchaseOrder[Reference="AMCEWEN-20021009123336171PDT"]'
PASSING po.OBJECT_VALUE AS "p");
XMLQUERY('$P/PURCHASEORDER/LINEITEMS/LINEITEM[@ITEMNUMBER=222]'
--------------------------------------------------------------
The Harder They Come


1 row selected.

If the XML data to be updated is XML schema-based and it refers to a namespace, then
the data to be inserted must also refer to the same namespace. Otherwise, an error is
raised because the inserted data does not conform to the XML schema.
Example 4–19 is the same as Example 4–18, except that the LineItem element to be
inserted refers to a namespace. This assumes that the relevant XML schema requires a
namespace for this element.
Example 4–19

Inserting an Element that Uses a Namespace

UPDATE purchaseorder
SET OBJECT_VALUE =
insertChildXML(OBJECT_VALUE,
'/PurchaseOrder/LineItems',
'LineItem',
XMLType('
The Harder They Come

'))
WHERE XMLExists('$p/PurchaseOrder[Reference="AMCEWEN-20021009123336171PDT"]'
PASSING OBJECT_VALUE AS "p");

Note that this use of namespaces is different from the use of a namespace argument to
function insertChildXML. Namespaces supplied in that optional argument apply
only to the XPath argument, not to the content to be inserted.

INSERTCHILDXMLBEFORE SQL Function
Oracle SQL function insertChildXMLbefore inserts one or more collection
elements as children of target parent elements. The insertion for each target occurs
immediately before a specified existing collection element. The existing XML
document that is the target of the insertion can be schema-based or non-schema-based.

XMLType Operations 4-25

Updating XML Data

A copy of the input XMLType instance is modified and returned. The original data is
unaffected. You can then use the returned data with SQL operation UPDATE to modify
database data.
Function insertChildXMLbefore has the following parameters (in order):
■
■

target-data (XMLType) – The XML data that is the target of the insertion.
parent-xpath (VARCHAR2) – An XPath 1.0 expression that locates the parent
elements within target-data. The child-data is inserted under each parent
element.
If parent-xpath matches an empty sequence of element nodes, then no insertion
is done, and target-data is returned unchanged (no error is raised). If
parent-xpath does not match a sequence of element nodes (in particular, if
parent-xpath matches one or more attribute or text nodes), then an error is
raised.

■

■

■

child-xpath (VARCHAR2) – A relative XPath 1.0 expression that locates the
existing child that will become the successor of the inserted child-data. It must
name a child element of the element indicated by parent-xpath, and it can
include a predicate.
child-data (XMLType) – The child element XML data to insert. This is of data
type XMLType, and it contains element nodes. Each of the top-level element nodes
in child-data must have the same data type as the element indicated by
child-xpath (or else an error is raised).
namespace (optional, VARCHAR2) – The namespace for parameters
parent-xpath, child-xpath, and child-data.

XML data child-data is inserted as one or more child elements under each of the
parent elements located at parent-xpath.
In order of decreasing precedence, function insertChildXMLbefore has the
following behavior for NULL arguments:
■

If child-name is NULL, then an error is raised.

■

If target-data or parent-xpath is NULL, then NULL is returned.

■

If child-data is NULL, then no insertion is done, and target-data is returned
unchanged.

Figure 4–5 shows the syntax.
Figure 4–5 INSERTCHILDXMLBEFORE Syntax
INSERTCHILDXMLBEFORE

,
(

XMLType_instance

,

XPath_string

,

child_expr

,

value_expr

namespace_string
)

INSERTCHILDXMLAFTER SQL Function
Oracle SQL function insertChildXMLafter inserts one or more collection elements
as children of target parent elements. The insertion for each target occurs immediately
after a specified existing collection element. The existing XML document that is the
target of the insertion can be schema-based or non-schema-based.

4-26 Oracle XML DB Developer's Guide

Updating XML Data

A copy of the input XMLType instance is modified and returned. The original data is
unaffected. You can then use the returned data with SQL operation UPDATE to modify
database data.
Function insertChildXMLafter has the following parameters (in order):
■
■

target-data (XMLType) – The XML data that is the target of the insertion.
parent-xpath (VARCHAR2) – An XPath 1.0 expression that locates the parent
elements within target-data. The child-data is inserted under each parent
element.
If parent-xpath matches an empty sequence of element nodes, then no insertion
is done, and target-data is returned unchanged (no error is raised). If
parent-xpath does not match a sequence of element nodes (in particular, if
parent-xpath matches one or more attribute or text nodes), then an error is
raised.

■

■

■

child-xpath (VARCHAR2) – A relative XPath 1.0 expression that locates the
existing child that will become the predecessor of the inserted child-data. It
must name a child element of the element indicated by parent-xpath, and it can
include a predicate.
child-data (XMLType) – The child element XML data to insert. This is of data
type XMLType, and it contains element nodes. Each of the top-level element nodes
in child-data must have the same data type as the element indicated by
child-xpath (or else an error is raised).
namespace (optional, VARCHAR2) – The namespace for parameters
parent-xpath, child-xpath, and child-data.

XML data child-data is inserted as one or more child elements under each of the
parent elements located at parent-xpath.
In order of decreasing precedence, function insertChildXMLafter has the
following behavior for NULL arguments:
■

If child-name is NULL, then an error is raised.

■

If target-data or parent-xpath is NULL, then NULL is returned.

■

If child-data is NULL, then no insertion is done, and target-data is returned
unchanged.

Figure 4–6 shows the syntax.
Figure 4–6 INSERTCHILDXMLAFTER Syntax
INSERTCHILDXMLAFTER

,
(

XMLType_instance

,

XPath_string

,

child_expr

,

value_expr

namespace_string
)

INSERTXMLBEFORE SQL Function
Oracle SQL function insertXMLbefore inserts one or more nodes of any kind
immediately before a target node that is not an attribute node. The XML document
that is the target of the insertion can be schema-based or non-schema-based.

XMLType Operations 4-27

Updating XML Data

A copy of the input XMLType instance is modified and returned. The original data is
unaffected. You can then use the returned data with SQL operation UPDATE to modify
database data.
Function insertXMLbefore has the following parameters (in order):
■
■

target-data (XMLType) – The XML data that is the target of the insertion.
successor-xpath (VARCHAR2) – An XPath 1.0 expression that locates zero or
more nodes in target-data of any kind except attribute nodes. XML-data is
inserted immediately before each of these nodes. Thus, the nodes in XML-data
become preceding siblings of each of the successor-xpath nodes.
If successor-xpath matches an empty sequence of nodes, then no insertion is
done, and target-data is returned unchanged (no error is raised). If
successor-xpath does not match a sequence of nodes that are not attribute
nodes, then an error is raised.

■

■

XML-data (XMLType) – The XML data to be inserted: one or more nodes of any
kind. The order of the nodes is preserved after the insertion.
namespace (optional, VARCHAR2) – The namespace for parameter
successor-xpath.

The XML-data nodes are inserted immediately before each of the non-attribute nodes
located at successor-xpath.
Function insertXMLbefore has the following behavior for NULL arguments:
■
■

If target-data or parent-xpath is NULL, then NULL is returned.
Otherwise, if child-data is NULL, then no insertion is done, and target-data
is returned unchanged.

Figure 4–7 shows the syntax.
Figure 4–7 INSERTXMLBEFORE Syntax
,
INSERTXMLBEFORE

(

XMLType_instance

Example 4–20

,

XPath_string

,

namespace_string

value_expr

)

Inserting a LineItem Element Before the First LineItem ELement

SELECT XMLQuery('$p/PurchaseOrder/LineItems/LineItem[1]'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
FROM purchaseorder po
WHERE XMLExists('$p/PurchaseOrder[Reference="AMCEWEN-20021009123336171PDT"]'
PASSING po.OBJECT_VALUE AS "p");
XMLQUERY('$P/PURCHASEORDER/LINEITEMS/LINEITEM[1]'PASSINGPO.OBJECT_
-----------------------------------------------------------------
Salesman


UPDATE purchaseorder
SET OBJECT_VALUE =
insertXMLbefore(OBJECT_VALUE,
'/PurchaseOrder/LineItems/LineItem[1]',
XMLType('
Brazil

4-28 Oracle XML DB Developer's Guide

Updating XML Data


'))
WHERE XMLExists('$p/PurchaseOrder[Reference="AMCEWEN-20021009123336171PDT"]'
PASSING OBJECT_VALUE AS "p");
SELECT XMLQuery('$p/PurchaseOrder/LineItems/LineItem[position() <= 2]'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
FROM purchaseorder po
WHERE XMLExists('$p/PurchaseOrder[Reference="AMCEWEN-20021009123336171PDT"]'
PASSING po.OBJECT_VALUE AS "p");
XMLQUERY('$P/PURCHASEORDER/LINEITEMS/LINEITEM[POSITION()<=2]'PASSINGPO.OBJECT_
-----------------------------------------------------------------------------
Brazil



Salesman



Note: Queries that use Oracle SQL function insertXMLbefore are
not optimized. For this reason, Oracle recommends that you use
function insertChildXML, insertChildXMLbefore, or
insertChildXMLafter instead. See "Performance Tuning for
XQuery" on page 5-29.

INSERTXMLAFTER SQL Function
Oracle SQL function insertXMLafter inserts one or more nodes of any kind
immediately after a target node that is not an attribute node. The XML document that
is the target of the insertion can be schema-based or non-schema-based. It is thus
similar to insertXMLbefore, but it inserts after, not before, the target node.
A copy of the input XMLType instance is modified and returned. The original data is
unaffected. You can then use the returned data with SQL operation UPDATE to modify
database data.
Function insertXMLafter has the following parameters (in order):
■
■

target-data (XMLType) – The XML data that is the target of the insertion.
successor-xpath (VARCHAR2) – An XPath 1.0 expression that locates zero or
more nodes in target-data of any kind except attribute nodes. XML-data is
inserted immediately after each of these nodes. Thus, the nodes in XML-data
become succeeding siblings of each of the successor-xpath nodes.
If successor-xpath matches an empty sequence of nodes, then no insertion is
done, and target-data is returned unchanged (no error is raised). If
successor-xpath does not match a sequence of nodes that are not attribute
nodes, then an error is raised.

■

■

XML-data (XMLType) – The XML data to be inserted: one or more nodes of any
kind. The order of the nodes is preserved after the insertion.
namespace (optional, VARCHAR2) – The namespace for parameter
successor-xpath.
XMLType Operations 4-29

Updating XML Data

The XML-data nodes are inserted immediately after each of the non-attribute nodes
located at successor-xpath.
Function insertXMLafter has the following behavior for NULL arguments:
If target-data or parent-xpath is NULL, then NULL is returned.

■

Otherwise, if child-data is NULL, then no insertion is done, and target-data
is returned unchanged.

■

Figure 4–8 shows the syntax.
Figure 4–8 INSERTXMLAFTER Syntax
,
INSERTXMLAFTER

(

XMLType_instance

,

XPath_string

,

namespace_string

value_expr

)

Note: Queries that use Oracle SQL function insertXMLafter are
not optimized. For this reason, Oracle recommends that you use
function insertChildXML, insertChildXMLbefore, or
insertChildXMLafter instead. See "Performance Tuning for
XQuery" on page 5-29.

APPENDCHILDXML SQL Function
Oracle SQL function appendChildXML inserts one or more nodes of any kind as the
last children of a given element node. The XML document that is the target of the
insertion can be schema-based or non-schema-based.
A copy of the input XMLType instance is modified and returned. The original data is
unaffected. You can then use the returned data with SQL operation UPDATE to modify
database data.
Function appendChildXML has the following parameters (in order):
■
■

target-data (XMLType)– The XML data containing the target parent element.
parent-xpath (VARCHAR2) – An XPath 1.0 expression that locates zero or more
element nodes in target-data that are the targets of the insertion operation. The
child-data is inserted as the last child or children of each of these parent
elements.
If parent-xpath matches an empty sequence of element nodes, then no insertion
is done, and target-data is returned unchanged (no error is raised). If
parent-xpath does not match a sequence of element nodes (in particular, if
parent-xpath matches one or more attribute or text nodes), then an error is
raised.

■

■

child-data (XMLType) – Child data to be inserted: one or more nodes of any
kind. The order of the nodes is preserved after the insertion.
namespace (optional, VARCHAR2) – The namespace for parameter
parent-xpath.

XML data child-data is inserted as the last child or children of each of the element
nodes indicated by parent-xpath.
Function appendChildXML has the following behavior for NULL arguments:
■

If target-data or parent-xpath is NULL, then NULL is returned.

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Otherwise, if child-data is NULL, then no insertion is done, and target-data
is returned unchanged.

■

Figure 4–9 shows the syntax.
Figure 4–9 APPENDCHILDXML Syntax
,
APPENDCHILDXML

(

XMLType_instance

Example 4–21

,

XPath_string

,

namespace_string

value_expr

)

Inserting a Date Element as the Last Child of an Action Element

SELECT XMLQuery('$p/PurchaseOrder/Actions/Action[1]'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
FROM purchaseorder po
WHERE XMLExists('$p/PurchaseOrder[Reference="AMCEWEN-20021009123336171PDT"]'
PASSING po.OBJECT_VALUE AS "p");
XMLQUERY('$P/PURCHASEORDER/ACTIONS/ACTION[1]'PASSINGPO.OBJECT_VALUE
------------------------------------------------------------------
KPARTNER

UPDATE purchaseorder
SET OBJECT_VALUE =
appendChildXML(OBJECT_VALUE,
'PurchaseOrder/Actions/Action[1]',
XMLType('2002-11-04'))
WHERE XMLExists('$p/PurchaseOrder[Reference="AMCEWEN-20021009123336171PDT"]'
PASSING OBJECT_VALUE AS "p");
SELECT XMLQuery('$p/PurchaseOrder/Actions/Action[1]'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
FROM purchaseorder po
WHERE XMLExists('$p/PurchaseOrder[Reference="AMCEWEN-20021009123336171PDT"]'
PASSING po.OBJECT_VALUE AS "p");
XMLQUERY('$P/PURCHASEORDER/ACTIONS/ACTION[1]'PASSINGPO.OBJECT_VALUE
------------------------------------------------------------------
KPARTNER
2002-11-04


Note: Queries that use Oracle SQL function appendChildXML are
not optimized. For this reason, Oracle recommends that you use
function insertChildXML, insertChildXMLbefore, or
insertChildXMLafter instead. See "Performance Tuning for
XQuery" on page 5-29.

DELETEXML SQL Function
Oracle SQL function deleteXML deletes XML nodes of any kind. The XML document
that is the target of the deletion can be schema-based or non-schema-based.

XMLType Operations 4-31

Updating XML Data

A copy of the input XMLType instance is modified and returned. The original data is
unaffected. You can then use the returned data with SQL operation UPDATE to modify
database data.
Function deleteXML has the following parameters (in order):
■

■

target-data (XMLType) – The XML data containing the target nodes (to be
deleted).
xpath (VARCHAR2) – An XPath 1.0 expression that locates zero or more nodes in
target-data that are the targets of the deletion operation. Each of these nodes is
deleted.
If xpath matches an empty sequence of nodes, then no deletion is done, and
target-data is returned unchanged (no error is raised). If xpath matches the
top-level element node, then an error is raised.

■

namespace (optional, VARCHAR2) – The namespace for parameter xpath.

The XML nodes located at xpath are deleted from target-data. Function
deleteXML returns NULL if target-data or xpath is NULL.
Figure 4–10 shows the syntax.
Figure 4–10 DELETEXML Syntax
,
DELETEXML

Example 4–22

(

XMLType_instance

,

namespace_string

XPath_string

)

Deleting LineItem Element Number 222

SELECT XMLQuery('$p/PurchaseOrder/LineItems/LineItem[@ItemNumber=222]'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
FROM purchaseorder po
WHERE XMLExists('$p/PurchaseOrder[Reference="AMCEWEN-20021009123336171PDT"]'
PASSING po.OBJECT_VALUE AS "p");
XMLQUERY('$P/PURCHASEORDER/LINEITEMS/LINEITEM[@ITEMNUMBER=222]'PASSINGPO
-----------------------------------------------------------------------
The Harder They Come


UPDATE purchaseorder
SET OBJECT_VALUE =
deleteXML(OBJECT_VALUE,
'/PurchaseOrder/LineItems/LineItem[@ItemNumber="222"]')
WHERE XMLExists('$p/PurchaseOrder[Reference="AMCEWEN-20021009123336171PDT"]'
PASSING OBJECT_VALUE AS "p");
SELECT XMLQuery('$p/PurchaseOrder/LineItems/LineItem[@ItemNumber=222]'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
FROM purchaseorder po
WHERE XMLExists('$p/PurchaseOrder[Reference="AMCEWEN-20021009123336171PDT"]'
PASSING po.OBJECT_VALUE AS "p");
XMLQUERY('$P/PURCHASEORDER/LINEITEMS/LINEITEM[@ITEMNUMBER=222]'PASSINGPO
-----------------------------------------------------------------------1 row selected.

4-32 Oracle XML DB Developer's Guide

Updating XML Data

XMLType Operations 4-33

Updating XML Data

4-34 Oracle XML DB Developer's Guide

5
Using XQuery with Oracle XML DB
This chapter describes how to use the XQuery language with Oracle XML DB. It covers
Oracle XML DB support for the language, including SQL/XML functions XMLQuery
and XMLTable and the SQL*Plus XQUERY command.
This chapter contains these topics:
■

Overview of XQuery in Oracle XML DB

■

Overview of the XQuery Language

■

SQL/XML Functions XMLQUERY and XMLTABLE

■

When To Use XQuery

■

Predefined Namespaces and Prefixes

■

URI Scheme oradb: Querying Table or View Data with XQuery

■

Oracle XQuery Extension Functions

■

XMLQUERY and XMLTABLE Examples

■

Performance Tuning for XQuery

■

XQuery Static Type-Checking in Oracle XML DB

■

SQL*Plus XQUERY Command

■

Using XQuery with PL/SQL, JDBC, and ODP.NET

■

Oracle XML DB Support for XQuery

Overview of XQuery in Oracle XML DB
Oracle XML DB support for the XQuery language is provided through a native
implementation of SQL/XML functions XMLQuery and XMLTable. As a convenience,
SQL*Plus command XQUERY is also provided, which lets you enter XQuery
expressions directly—in effect, this command turns SQL*Plus into an XQuery
command-line interpreter.
Oracle XML DB compiles XQuery expressions that are passed as arguments to
SQL/XML functions XMLQuery, XMLTable, XMLExists, and XMLCast. This
compilation produces SQL query blocks and operator trees that use SQL/XML
functions and XPath functions. A SQL statement that includes XMLQuery, XMLTable,
XMLExists, or XMLCast is compiled and optimized as a whole, leveraging both
relational database and XQuery-specific optimization technologies. Depending on the
XML storage and indexing methods used, XPath functions can be further optimized.
The resulting optimized operator tree is executed in a streaming fashion.

Using XQuery with Oracle XML DB 5-1

Overview of the XQuery Language

See Also:
■

■

■

SQL/XML Functions XMLQUERY and XMLTABLE and SQL*Plus
XQUERY Command
Oracle XQuery Extension Functions for Oracle-specific XQuery
functions that extend the language
Oracle XML DB Support for XQuery for details on Oracle
XML DB support for XQuery

Overview of the XQuery Language
Oracle XML DB supports the latest version of the XQuery language specification, W3C
XQuery 1.0 Recommendation. This section presents a brief overview of the language.
For more information, consult a recent book on the language or refer to the standards
documents that define it, which are available at http://www.w3c.org.

Functional Language Based on Sequences
XQuery 1.0 is the W3C language designed for querying XML data. It is similar to SQL
in many ways, but just as SQL is designed for querying structured, relational data,
XQuery is designed especially for querying semi-structured, XML data from a variety
of data sources. You can use XQuery to query XML data wherever it is found, whether
it is stored in database tables, available through Web Services, or otherwise created on
the fly. In addition to querying XML data, XQuery can be used to construct XML data.
In this regard, XQuery can serve as an alternative or a complement to both XSLT and
the other SQL/XML publishing functions, such as XMLElement.
XQuery builds on the Post-Schema-Validation Infoset (PSVI) data model, which unites
the XML Information Set (Infoset) data model and the XML Schema type system.
XQuery defines a new data model based on sequences: the result of each XQuery
expression is a sequence. XQuery is all about manipulating sequences. This makes
XQuery similar to a set-manipulation language, except that sequences are ordered and
can contain duplicate items. XQuery sequences differ from the sequences in some
other languages in that nested XQuery sequences are always flattened in their effect.
In many cases, sequences can be treated as unordered, to maximize optimization –
where this is available, it is under your control. This unordered mode can be applied
to join order in the treatment of nested iterations (for), and it can be applied to the
treatment of XPath expressions (for example, in /a/b, the matching b elements can be
processed without regard to document order).
An XQuery sequence consists of zero or more items, which can be either atomic
(scalar) values or XML nodes. Items are typed using a rich type system that is based
upon the types of XML Schema. This type system is a major change from that of XPath
1.0, which is limited to simple scalar types such as Boolean, number, and string.
XQuery is a functional language. As such, it consists of a set of possible expressions that
are evaluated and return values (which, for XQuery, are sequences). As a functional
language, XQuery is also referentially transparent, generally: the same expression
evaluated in the same context returns the same value.
Exceptions to this desirable mathematical property include the following:
■

XQuery expressions that derive their value from interaction with the external
environment. For example, an expression such as fn:current-time(...) or
fn:doc(...) does not necessarily always return the same value, since it depends

5-2 Oracle XML DB Developer's Guide

Overview of the XQuery Language

on external conditions that can change (the time changes; the content of the target
document might change).
In some cases, like that of fn:doc, XQuery is defined to be referentially
transparent within the execution of a single query: within a query, each invocation
of fn:doc with the same argument results in the same document.
■

XQuery expressions that are defined to be dependent on the particular XQuery
language implementation. The result of evaluating such expressions might vary
between implementations. Function fn:doc is an example of a function that is
essentially implementation-defined.

Referential transparency applies also to XQuery variables: the same variable in the
same context has the same value. Functional languages are like mathematics
formalisms in this respect and unlike procedural, or imperative, programming
languages. A variable in a procedural language is really a name for a memory location;
it has a current value, or state, as represented by its content at any time. A variable in a
declarative language such as XQuery is really a name for a static value.

XQuery Expressions
XQuery expressions are case-sensitive. The expressions include the following:
■

■

■

■

■

■

primary expression – literal, variable, or function application. A variable name
starts with a dollar-sign ($) – for example, $foo. Literals include numerals,
strings, and character or entity references.
XPath expression – Any XPath expression. The XPath 2.0 standard is a subset of
XQuery.
FLWOR expression – The most important XQuery expression, composed of the
following, in order, from which FLWOR takes its name: for, let, where, order
by, return.
XQuery sequence – The comma (,) constructor creates sequences.
Sequence-manipulating functions such as union and intersect are also
available. All XQuery sequences are effectively flat: a nested sequence is treated as
its flattened equivalent. Thus, for instance, (1, 2, (3, 4, (5), 6), 7) is
treated as (1, 2, 3, 4, 5, 6, 7). A singleton sequence, such as (42), acts
the same in most XQuery contexts as does its single item, 42. Remember that the
result of any XQuery expression is a sequence.
Direct (literal) constructions – XML element and attribute syntax automatically
constructs elements and attributes: what you see is what you get. For example, the
XQuery expression 33 constructs the XML element 33.
Computed (dynamic) constructions – You can construct XML data at run time
using computed values. For example, the following XQuery expression constructs
this XML data: tata titi why? .
attribute toto {2+3},
element bar {"tata", "titi"},
text {" why? "}

In this example, element foo is a direct construction; the other constructions are
computed. In practice, the arguments to computed constructors are not literals
(such as toto and "tata"), but expressions to be evaluated (such as 2+3). Both
the name and the value arguments of an element or attribute constructor can be
computed. Braces ({, }) are used to mark off an XQuery expression to be
evaluated.

Using XQuery with Oracle XML DB 5-3

Overview of the XQuery Language

■

Conditional expression – As usual, but remember that each part of the expression
is itself an arbitrary expression. For instance, in this conditional expression, each of
these subexpressions can be any XQuery expression: something,
somethingElse, expression1, and expression2.
if (something < somethingElse) then expression1 else expression2

■

Arithmetic, relational expression – As usual, but remember that each relational
expression returns a (Boolean1) value. Examples:
2 + 3
42 < $a + 5
(1, 4) = (1, 2)
5 > 3 eq true()

■

Quantifier expression – Universal (every) and existential (some) quantifier
functions provide shortcuts to using a FLWOR expression in some cases.
Examples:
every $foo in doc("bar.xml")//Whatever satisfies $foo/@bar > 42
some $toto in (42, 5), $titi in (123, 29, 5) satisfies $toto = $titi

■

■

Regular expression – XQuery regular expressions are based on XML Schema 1.0
and Perl. (See Support for XQuery Functions and Operators on page 5-43.)
Type expression – An XQuery expression that represents an XQuery type.
Examples: item(), node(), attribute(), element(), document-node(),
namespace(), text(), xs:integer, xs:string.2
Type expressions can have occurrence indicators: ? (optional: zero or one), *
(zero or more), + (one or more). Examples: document-node(element())*,
item()+, attribute()?.
XQuery also provides operators for working with types. These include cast as,
castable as, treat as, instance of, typeswitch, and validate. For
example, "42" cast as xs:integer is an expression whose value is the
integer 2. (It is not, strictly speaking, a type expression, because its value does not
represent a type.)

FLWOR Expressions
As for XQuery in general, there is a lot to learn about FLWOR expressions. This section
provides only a brief overview.
FLWOR is the most general expression syntax in XQuery. FLWOR (pronounced
"flower") stands for for, let, where, order by, and return. A FLWOR expression
has at least one for or let clause and a return clause; single where and order by
clauses are optional.
■

for – Bind one or more variables each to any number of values, in turn. That is,
for each variable, iterate, binding the variable to a different value for each
iteration.
At each iteration, the variables are bound in the order they appear, so that the
value of a variable $earlier that is listed before a variable $later in the for

1
2

The value returned is a sequence, as always. However, in XQuery, a sequence of one item is
equivalent to that item itself. In this case, the single item is a Boolean value.
Namespace prefix xs is predefined for the XML Schema namespace,
http://www.w3.org/2001/XMLSchema.

5-4 Oracle XML DB Developer's Guide

SQL/XML Functions XMLQUERY and XMLTABLE

list, can be used in the binding of variable $later. For example, during its second
iteration, this expression binds $i to 4 and $j to 6 (2+4):
for $i in (3, 4), $j in ($i, 2+$i)
■

let – Bind one or more variables.
Just as with for, a variable can be bound by let to a value computed using
another variable that is listed previously in the binding list of the let (or an
enclosing for or let). For example, this expression binds $j to 5 (3+2):
let $i := 3, $j := $i + 2

■

■
■

where – Filter the for and let variable bindings according to some condition.
This is similar to a SQL WHERE clause.
order by – Sort the result of where filtering.
return – Construct a result from the ordered, filtered values. This is the result of
the FLWOR expression as a whole. It is a flattened sequence.

Expressions for and let act similarly to a SQL FROM clause. Expression where acts
like a SQL WHERE clause Expression order by is similar to ORDER BY in SQL.
Expression return is like SELECT in SQL. Except for the two keywords whose names
are the same in both languages (where, order by), FLWOR clause order is more or
less opposite to the SQL clause order, but the meanings of the corresponding clauses
are quite similar.
Note that using a FLWOR expression (with order by) is the only way to construct an
XQuery sequence in any order other than document order.

SQL/XML Functions XMLQUERY and XMLTABLE
SQL/XML functions XMLQuery, XMLTable, XMLExists, and XMLCast are defined
by the SQL/XML standard as a general interface between the SQL and XQuery
languages. As is the case for the other SQL/XML functions, these functions let you
take advantage of the power and flexibility of both SQL and XML. Using these
functions, you can construct XML data using relational data, query relational data as if
it were XML, and construct relational data from XML data.
SQL functions XMLExists and XMLCast are documented elsewhere in this manual.
This section presents functions XMLQuery and XMLTable, but many of the examples
in this chapter use also XMLExists, and XMLCast. In terms of typical use:
■

XMLQuery and XMLCast are typically used in a SELECT list.

■

XMLTable is typically used in a SQL FROM clause.

■

XMLExists is typically used in a SQL WHERE clause.

Both XMLQuery and XMLTable evaluate an XQuery expression. In the XQuery
language, an expression always returns a sequence of items. Function XMLQuery
aggregates the items in this sequence to return a single XML document or fragment.
Function XMLTable returns a SQL table whose rows each contain one item from the
XQuery sequence.

Using XQuery with Oracle XML DB 5-5

SQL/XML Functions XMLQUERY and XMLTABLE

See Also:
■

■

■

■

■

Oracle Database SQL Language Reference for information about
Oracle support for the SQL/XML standard
http://www.sqlx.org for information about SQL/XML
functions
http://www.w3.org for information about the XQuery
language
"Generating XML using SQL Functions" on page 18-2 for
information about using other SQL/XML functions with Oracle
XML DB
"Querying XMLType Data using SQL/XML Functions XMLExists
and XMLCast" on page 4-2

XMLQUERY SQL/XML Function in Oracle XML DB
You use SQL/XML function XMLQuery to construct or query XML data. This function
takes as arguments an XQuery expression, as a string literal, and an optional XQuery
context item, as a SQL expression. The context item establishes the XPath context in
which the XQuery expression is evaluated. Additionally, XMLQuery accepts as
arguments any number of SQL expressions whose values are bound to XQuery
variables during the XQuery expression evaluation. The function returns the result of
evaluating the XQuery expression, as an XMLType instance.
Figure 5–1 XMLQUERY Syntax
XMLQUERY

XML_passing_clause
(

NULL

XQuery_string

RETURNING

CONTENT

ON

EMPTY
)

XML_passing_clause ::=
,
BY
PASSING

■

■

VALUE

AS

identifier

expr

XQuery_string is a complete XQuery expression, possibly including a prolog, as
a literal string.
The XML_passing_clause is the keyword PASSING followed by one or more
SQL expressions (expr) that each return an XMLType instance or an instance of a
SQL scalar data type (that is, not an object or collection data type). Each expression
(expr) can be a table or view column value, a PL/SQL variable, or a bind variable
with proper casting. All but possibly one of the expressions must each be followed
by the keyword AS and an XQuery identifier. The result of evaluating each
expr is bound to the corresponding identifier for the evaluation of XQuery_
string. If there is an expr that is not followed by an AS clause, then the result of
evaluating that expr is used as the context item for evaluating XQuery_string.
Oracle XML DB supports only passing BY VALUE, not passing BY REFERENCE, so
the clause BY VALUE is implicit and can be omitted.

5-6 Oracle XML DB Developer's Guide

SQL/XML Functions XMLQUERY and XMLTABLE

■

RETURNING CONTENT indicates that the value returned by an application of
XMLQuery is an instance of parameterized XML type XML(CONTENT), not
parameterized type XML(SEQUENCE). It is a document fragment that conforms to
the extended Infoset data model. As such, it is a single document node with any
number of children. The children can each be of any XML node type; in particular,
they can be text nodes.
Oracle XML DB supports only the RETURNING CONTENT clause of SQL/XML
function XMLQuery; it does not support the RETURNING SEQUENCE clause.

You can pass an XMLType column, table, or view as the context-item argument to
function XMLQuery—see, for example, Example 5–8.
To query a relational table or view as if it were XML data, without having to first
create a SQL/XML view on top of it, use XQuery function fn:collection within an
XQuery expression, passing as argument a URI that uses the URI-scheme name oradb
together with the database location of the data. See "URI Scheme oradb: Querying
Table or View Data with XQuery" on page 5-10.
Prior to Oracle Database 11g Release 2, some users employed
Oracle SQL functions extract and extractValue to do some of
what can be done better using SQL/XML functions XMLQuery and
XMLCast. SQL functions extract and extractValue are deprecated
in Oracle Database 11g Release 2.

Note:

See Also:
■

■

http://www.sqlx.org for information about the definition of
SQL/XML function XMLQuery
Oracle Database SQL Language Reference for reference information
about SQL/XML function XMLQuery in Oracle Database

XMLTABLE SQL/XML Function in Oracle XML DB
You use SQL/XML function XMLTable to decompose the result of an
XQuery-expression evaluation into the relational rows and columns of a new, virtual
table. You can then insert the virtual table into a pre-existing database table, or you can
query it using SQL—in a join expression, for example (see Example 5–9). You use
XMLTable in a SQL FROM clause.
Figure 5–2 XMLTABLE Syntax
XML_namespaces_clause
XMLTABLE

,

(

XQuery_string

XMLTABLE_options

)

XML_namespaces_clause ::=
,
string
XMLNAMESPACES

(

AS

identifier

DEFAULT

string
)

Using XQuery with Oracle XML DB 5-7

SQL/XML Functions XMLQUERY and XMLTABLE

XMLTABLE_options ::=
,
XML_passing_clause

COLUMNS

XML_table_column

XML_passing_clause ::=
,
BY

VALUE

PASSING

AS

identifier

expr

XML_table_column ::=
FOR
column

ORDINALITY
PATH

string

DEFAULT

expr

datatype

■

■

■

■

XQuery_string is a complete XQuery expression, possibly including a prolog, as
a literal string. The value of the expression serves as input to the XMLTable
function; it is this XQuery result that is decomposed and stored as relational data.
The optional XMLNAMESPACES clause contains XML namespace declarations that
are referenced by XQuery_string and by the XPath expression in the PATH
clause of XML_table_column.
The XML_passing_clause is the keyword PASSING followed by one or more
SQL expressions (expr) that each return an XMLType instance or an instance of a
SQL scalar data type (that is, not an object or collection data type). Each expression
(expr) can be a table or view column value, a PL/SQL variable, or a bind
variables with proper casting. All but possibly one of the expressions must each be
followed by the keyword AS and an XQuery identifier. The result of
evaluating each expr is bound to the corresponding identifier for the
evaluation of XQuery_string. If there is an expr that is not followed by an AS
clause, then the result of evaluating that expr is used as the context item for
evaluating XQuery_string. Oracle XML DB supports only passing BY VALUE,
not passing BY REFERENCE, so the clause BY VALUE is implicit and can be
omitted.
The optional COLUMNS clause defines the columns of the virtual table to be created
by XMLTable.
■

■

■

■

If you omit the COLUMNS clause, then XMLTable returns a row with a single
XMLType pseudo-column, named COLUMN_VALUE.
FOR ORDINALITY specifies that column is to be a column of generated row
numbers (SQL data type NUMBER). There must be at most one FOR
ORDINALITY clause.
For each resulting column except the FOR ORDINALITY column, you must
specify the column data type, which can be XMLType or any other SQL data
type (called datatype in the syntax description).
The optional PATH clause specifies that the portion of the XQuery result that is
addressed by XQuery expression string is to be used as the column content.
You can use multiple PATH clauses to split the XQuery result into different
virtual-table columns.

5-8 Oracle XML DB Developer's Guide

Predefined Namespaces and Prefixes

If you omit PATH, then the XQuery expression column is assumed. For
example, these two expressions are equivalent:
XMLTable(... COLUMNS foo)
XMLTable(... COLUMNS foo PATH 'FOO')

The XQuery expression string must represent a relative path; it is relative to
the path XQuery_string.
■

The optional DEFAULT clause specifies the value to use when the PATH
expression results in an empty sequence (or NULL). Its expr is an XQuery
expression that is evaluated to produce the default value.
See Also:
■

■

http://www.sqlx.org for information about the definition of
SQL/XML function XMLTable
Oracle Database SQL Language Reference for reference information
about SQL/XML function XMLTable in Oracle Database

Prior to Oracle Database 11g Release 2, some users employed
Oracle SQL function XMLSequence within a SQL TABLE collection
expression, that is, TABLE(XMLSequence(...)), to do some of what
can be done better using SQL/XML function XMLTable. Function
XMLSequence is deprecated in Oracle Database 11g Release 2.
Note:

See Oracle Database SQL Language Reference for information about the
SQL TABLE collection expression.

When To Use XQuery
You can use XQuery to do many of the same things that you might do using the
SQL/XML generation functions or XSLT; there is a great deal of overlap. The decision
to use one or the other tool to accomplish a given task can be based on many
considerations, most of which are not specific to Oracle Database. Please consult
external documentation on this general question.
One general rule of thumb is that XQuery is often used when the focus is the world of
XML data, while the SQL/XML generation functions (XMLElement, XMLAgg, and so
on) are often used when the focus is the world of relational data.
Other things being equal, if a query constructs an XML document from fragments
extracted from existing XML documents, then it is likely that an XQuery FLOWR
expression is simpler (simplifying code maintenance) than extracting scalar values
from relational data and constructing appropriate XML data using SQL/XML
generation functions. If, instead, a query constructs an XML document from existing
relational data, the SQL/XML generation functions can often be more suitable.
With respect to Oracle XML DB, you can expect the same general level of performance
using the SQL/XML generation functions as with XMLQuery and XMLTable—all are
subject to rewrite optimizations.

Predefined Namespaces and Prefixes
The following namespaces and prefixes are predefined for use with XQuery in Oracle
XML DB:

Using XQuery with Oracle XML DB 5-9

URI Scheme oradb: Querying Table or View Data with XQuery

Table 5–1

Predefined Namespaces and Prefixes

Prefix Namespace

Description

ora

Oracle XML DB namespace

http://xmlns.oracle.com/xdb

local http://www.w3.org/2003/11/xpath-local-functions XPath local function declaration
namespace
fn

http://www.w3.org/2003/11/xpath-functions

XPath function namespace

xml

http://www.w3.org/XML/1998/namespace

XML namespace

xs

http://www.w3.org/2001/XMLSchema

XML Schema namespace

xsi

http://www.w3.org/2001/XMLSchema-instance

XML Schema instance namespace

You can use these prefixes in XQuery expressions without first declaring them in the
XQuery-expression prolog. You can redefine any of them except xml in the prolog. All
of these prefixes except ora are predefined in the XQuery standard.

URI Scheme oradb: Querying Table or View Data with XQuery
You can use XQuery functions fn:doc and fn:collection to query resources in
Oracle XML DB Repository—see"Querying XML Data in Oracle XML DB Repository
using XQuery" on page 5-16. This section is about using XQuery function
fn:collection to query data in database tables and views.
To do this, you pass function fn:collection a URI argument that specifies the table
or view to query. The Oracle URI scheme oradb identifies this usage: without it, the
argument is treated as a repository location.
The table or view that is queried can be relational or of type XMLType. If relational, its
data is converted on the fly and treated as XML. The result returned by
fn:collection is always an XQuery sequence.
■

■

For an XMLType table, the root element of each XML document returned by
fn:collection is the same as the root element of an XML document in the
table.
For a relational table, the root element of each XML document returned by
fn:collection is ROW. The children of the ROW element are elements with the
same names (uppercase) as columns of the table. The content of a child element
corresponds to the column data. That content is an XML element if the column is
of type XMLType; otherwise (the column is a scalar type), the content is of type
xs:string.

The format of the URI argument passed to fn:collection is as follows:
■

For an XMLType or relational table or view, TABLE, in database schema
DB-SCHEMA:
oradb:/DB-SCHEMA/TABLE/

You can use PUBLIC for DB-SCHEMA if TABLE is a public synonym or TABLE is a
table or view that is accessible to the database user currently logged in.
■

For an XMLType column in a relational table or view:
oradb:/DB-SCHEMA/REL-TABLE/ROWPRED/X-COL

5-10 Oracle XML DB Developer's Guide

Oracle XQuery Extension Functions

REL-TABLE is a relational table or view; PRED is an XPath predicate that does not
involve any XMLType columns; and X-COL is an XMLType column in REL-TABLE.
PRED is optional; DB-SCHEMA, REL-TABLE, and X-COL are required.
Optional XPath predicate PRED must satisfy the following conditions:
■
■

■

It does not involve any XMLType columns.
It involves only conjunctions (and) and disjunctions (or) of general equality and
inequality comparisons (=, !=, >, <, >=, and <=).
For each comparison operation: Either both sides name (non-XML) columns in
REL-TABLE or one side names such a column and the other is a value of the
proper type, as specified in Table 5–2. Use of any other type raises an error.

Table 5–2

oradb Expressions: Column Types for Comparisons

Relational Column Type

XQuery Value Type

VARCHAR2, CHAR

xs:string or string literal

NUMBER, FLOAT, BINARY_FLOAT, BINARY_DOUBLE xs:decimal, xs:float, xs:double,
or numeric literal
DATE, TIMESTAMP, TIMESTAMP WITH TIMEZONE, xs:date, xs:time, or xs:dateTime
TIMESTAMP WITH LOCAL TIMEZONE
INTERVAL YEAR TO MONTH

xs:yearMonthDuration

INTERVAL DAY TO SECOND

xs:dayTimeDuration

RAW

xs:hexBinary

ROWID

xs:string or string literal

For example, this XQuery expression represents all XML documents in XMLType
column warehouse_spec of table oe.warehouses, for the rows where column
warehouse_id has a value less than 6:
fn:collection('oradb:/OE/WAREHOUSES/ROW[WAREHOUSE_ID < 6]/WAREHOUSE_SPEC')

See Also:

"Querying Table or View Data using XQuery" on page 5-18

Oracle XQuery Extension Functions
Oracle XML DB adds some XQuery functions to those provided in the W3C standard.
These additional functions are in the Oracle XML DB namespace,
http://xmlns.oracle.com/xdb, which uses the predefined prefix ora. This
section describes these Oracle extension functions.

ora:contains XQuery Function
ora:contains Syntax
ora:contains (input_text, text_query [, policy_name] [, policy_owner])

XQuery and XPath function ora:contains can be used in an XQuery expression in a
call to SQL/XML function XMLQuery, XMLTable, or XMLExists. It is used to restrict
a structural search with a full-text predicate. Function ora:contains returns a
positive integer when the input_text matches text_query (the higher the number,
the more relevant the match), and zero otherwise. When used in an XQuery expression
(that is not also an XPath expression), the XQuery return type is xs:integer();

Using XQuery with Oracle XML DB 5-11

Oracle XQuery Extension Functions

when used in an XPath expression outside of an XQuery expression, the XPath return
type is number.
Argument input_text must evaluate to a single text node or an attribute. The syntax
and semantics of text_query in ora:contains are the same as text_query in
contains, with a few restrictions.
See Also:

"ora:contains XQuery Function" on page 12-17

ora:matches XQuery Function
ora:matches Syntax
ora:matches (target_string, match_pattern [, match_parameter])

XQuery function ora:matches lets you use a regular expression to match text in a
string. It returns true() if its target_string argument matches its
regular-expression match_pattern argument and false() otherwise. If target_
string is the empty sequence, false() is returned. Optional argument match_
parameter is a code that qualifies matching: case-sensitivity and so on.
The behavior of XQuery function ora:matches is the same as that of SQL condition
REGEXP_LIKE, but the types of its arguments are XQuery types instead of SQL data
types. The argument types are as follows:
■

target_string – xs:string?3

■

match_pattern – xs:string

■

match_parameter – xs:string
See Also: Oracle Database SQL Language Reference for information
about SQL condition REGEXP_LIKE

ora:replace XQuery Function
ora:replace Syntax
ora:replace (target_string, match_pattern, replace_string [, match_parameter])

XQuery function ora:replace lets you use a regular expression to replace matching
text in a string. Each occurrence in target_string that matches regular-expression
match_pattern is replaced by replace_string. It returns the new string that
results from the replacement. If target_string is the empty sequence, then the
empty string ("") is returned. Optional argument match_parameter is a code that
qualifies matching: case-sensitivity and so on.
The behavior of XQuery function ora:replace is the same as that of SQL function
regexp_replace, but the types of its arguments are XQuery types instead of SQL
data types. The argument types are as follows:
■

target_string – xs:string?4

■

match_pattern – xs:string

■

replace_string – xs:string

3
4

The question mark (?) here is a zero-or-one occurrence indicator that indicates that the
argument can be the empty sequence. See "XQuery Expressions" on page 5-3.
The question mark (?) here is a zero-or-one occurrence indicator that indicates that the
argument can be the empty sequence. See "XQuery Expressions" on page 5-3.

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■

match_parameter – xs:string

In addition, ora:replace requires argument replace_string (it is optional in
regexp_replace) and it does not use arguments for position and number of
occurrences – search starts with the first character and all occurrences are replaced.
See Also: Oracle Database SQL Language Reference for information
about SQL function regexp_replace

ora:sqrt XQuery Function
ora:sqrt Syntax
ora:sqrt (number)

XQuery function ora:sqrt returns the square root of its numeric argument, which
can be of XQuery type xs:decimal, xs:float, or xs:double. The returned value
is of the same XQuery type as the argument.

ora:tokenize XQuery Function
ora:tokenize Syntax
ora:tokenize (target_string, match_pattern [, match_parameter])

XQuery function ora:tokenize lets you use a regular expression to split the input
string target_string into a sequence of strings. It treats each substring that
matches the regular-expression match_pattern as a separator indicating where to
split.
It returns the sequence of tokens as an XQuery value of type xs:string* (a sequence
of xs:string values). If target_string is the empty sequence, it is returned.
Optional argument match_parameter is a code that qualifies matching:
case-sensitivity and so on.
The argument types are as follows:
■

target_string – xs:string?5

■

match_pattern – xs:string

■

match_parameter – xs:string

Oracle XQuery Extension-Expression Pragmas
The W3C XQuery specification lets an implementation provide
implementation-defined extension expressions. An XQuery extension expression is an
XQuery expression that is enclosed in braces ({, }) and prefixed by an
implementation-defined pragma.
The Oracle implementation provides the pragmas described in this section. No other
pragmas are recognized than those listed here. Use of any other pragma, or use of any
of these pragmas with incorrect pragma content (for example, (#ora:view_on_null
something_else #)), raises an error.

5

The question mark (?) here is a zero-or-one occurrence indicator that indicates that the
argument can be the empty sequence. See "XQuery Expressions" on page 5-3.

Using XQuery with Oracle XML DB 5-13

Oracle XQuery Extension-Expression Pragmas

In the ora:view_on_null examples here, assume that table null_test has
columns a and b of type VARCHAR2(10), and that column b (but not a) is empty.
■

■

(#ora:defaultTable #) – Specify the default table used to store repository
data. Use this to improve the performance of repository queries that use Query
function fn:doc or fn:collection. See "Using Oracle XQuery Pragma
ora:defaultTable" on page 5-36.
(#ora:invalid_path empty #) – Treat an invalid XPath expression as if its
targeted nodes do not exist. For example:
SELECT XMLQuery('(#ora:invalid_path empty #)
{exists($p/PurchaseOrder//NotInTheSchema)}'
PASSING OBJECT_VALUE AS "p" RETURNING CONTENT)
FROM oe.purchaseorder p;

The XML schema for table oe.purchaseorder does not allow any such node
NotInTheSchema as a descendant of node PurchaseOrder. Without the
pragma, the use of this invalid XPath expression would raise an error. But with the
pragma, the calling context acts just as if the XPath expression had targeted no
nodes. That calling context in this example is XQuery function exists, which
returns XQuery Boolean value false when passed an empty node sequence.
(XQuery function exists is used in this example only to illustrate the behavior;
the pragma is not especially related to function exists.)
■

(#ora:view_on_null empty #) – XQuery function fn:collection returns
an empty XML element for each NULL column. For example, the following query
returns x:
SELECT XMLQuery('(#ora:view_on_null empty #)
{for $i in fn:collection("oradb:/PUBLIC/NULL_TEST")/ROW
return $i}'
RETURNING CONTENT)
FROM DUAL;

■

(#ora:view_on_null null #) – XQuery function fn:collection returns
no element for a NULL column. For example, the following query returns
x:
SELECT XMLQuery('(#ora:view_on_null null #)
{for $i in fn:collection("oradb:/PUBLIC/NULL_TEST")/ROW
return $i}'
RETURNING CONTENT)
FROM DUAL;

■

(#ora:xq_proc #) – Do not optimize XQuery procedure calls in the XQuery
expression that follows the pragma; use functional evaluation instead.
This has the same effect as the SQL hint /*+ NO_XML_QUERY_REWRITE */, but
the scope of the pragma is only the XQuery expression that follows it (not an
entire SQL statement).
"Turning Off Use of XMLIndex" on page 6-30 for
information about optimizer hint NO_XML_QUERY_REWRITE

See Also:

■

(#ora:xq_qry #) – Try to optimize the XQuery expression that follows the
pragma. That is, if possible, do not evaluate it functionally.
As an example of using both ora:xq_proc and ora:xq_qry, in the following
query the XQuery expression argument to XMLQuery will in general be evaluated

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functionally, but the fn:collection subexpressions that are preceded by
pragma ora:xq_qry will be optimized, if possible.
SELECT XMLQuery('(#ora:xq_proc#)
(: Do not optimize the XQuery expression :)
{for $i in (#ora:xq_qry#)
(: Optimize this subexpression :)
{fn:collection("oradb:/HR/REGIONS")},
$j in (#ora:xq_qry#)
(: Optimize this subexpression :)
{fn:collection("oradb:/HR/COUNTRIES")}
where $i/ROW/REGION_ID = $j/ROW/REGION_ID
and $i/ROW/REGION_NAME = $regionname
return $j}'
PASSING CAST('®ION' AS VARCHAR2(40)) AS "regionname"
RETURNING CONTENT)
AS asian_countries FROM DUAL;

XMLQUERY and XMLTABLE Examples
XQuery is a very general and expressive language, and SQL/XML functions
XMLQuery, XMLTable, and XMLExists combine that power of expression and
computation with the similar strengths of SQL. This section illustrates some of what
you can do with these two SQL/XML functions. See "XMLEXISTS SQL/XML
Function" on page 4-3 for information about XMLExists.
You typically use XQuery with Oracle XML DB in the following ways. The examples
here are organized to reflect these different uses.
■

Query XML data in Oracle XML DB Repository.
See "Querying XML Data in Oracle XML DB Repository using XQuery".

■

Query a relational table or view as if it were XML data. To do this, you use Oracle
XQuery function fn:collection, passing as argument a URI that uses the
URI-scheme name oradb together with the database location of the data.
See "Querying Table or View Data using XQuery".

■

Query XMLType relational data, possibly decomposing the resulting XML into
relational data using function XMLTable.
See "Using XQuery with XMLType Data".

Example 5–1 creates Oracle XML DB Repository resources that are used in some of the
other examples in this chapter.
Example 5–1 Creating Resources for Examples
DECLARE
res BOOLEAN;
empsxmlstring VARCHAR2(300):=
'

';
empsxmlnsstring VARCHAR2(300):=
'

';

salary="21000"/>
salary="310000"/>
salary="100001"/>

salary="21000"/>
salary="310000"/>
salary="100001"/>

Using XQuery with Oracle XML DB 5-15

XMLQUERY and XMLTABLE Examples

deptsxmlstring VARCHAR2(300):=
'




';
BEGIN
res := DBMS_XDB.createResource('/public/emps.xml',
empsxmlstring);
res := DBMS_XDB.createResource('/public/empsns.xml', empsxmlnsstring);
res := DBMS_XDB.createResource('/public/depts.xml', deptsxmlstring);
END;
/

XQuery Is About Sequences
It is important to keep in mind that XQuery is a general sequence-manipulation
language. Its expressions and their results are not necessarily XML data. An XQuery
sequence can contain items of any XQuery type, which includes numbers, strings,
Boolean values, dates, and various types of XML node (document-node(),
element(), attribute(), text(), namespace(), and so on). Example 5–2
provides a sampling.
Example 5–2 XMLQuery Applied to a Sequence of Items of Different Types
SELECT XMLQuery('(1, 2 + 3, "a", 100 to 102, 33)'
RETURNING CONTENT) AS output
FROM DUAL;
OUTPUT
-------------------------1 5 a 100 101 10233
1 row selected.

Example 5–2 applies SQL/XML function XMLQuery to an XQuery sequence that
contains items of several different kinds:
■

an integer literal: 1

■

a arithmetic expression: 2 + 3

■

a string literal: "a"

■

a sequence of integers: 100 to 102

■

a constructed XML element node: 33

Example 5–2 also shows construction of a sequence using the comma operator (,) and
parentheses ((, )) for grouping.
The sequence expression 100 to 102 evaluates to the sequence (100, 101, 102),
so the argument to XMLQuery here is a sequence that contains a nested sequence. The
sequence argument is automatically flattened, as is always the case for XQuery
sequences. The argument is, in effect, (1, 5, "a", 100, 101, 102,
33).

Querying XML Data in Oracle XML DB Repository using XQuery
This section presents examples of using XQuery with XML data in Oracle XML DB
Repository. You use XQuery functions fn:doc and fn:collection to query file and

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folder resources in the repository, respectively. The examples in this section use
XQuery function fn:doc to obtain a repository file that contains XML data, and then
bind XQuery variables to parts of that data using for and let FLWOR-expression
clauses.
See Also: XQuery Functions fn:doc, fn:collection, and
fn:doc-available

Example 5–3 queries two XML-document resources in Oracle XML DB Repository:
/public/emps.xml and /public/depts.xml. It illustrates the use of fn:doc and
each of the possible FLWOR-expression clauses.
Example 5–3 FLOWR Expression using for, let, order by, where, and return
SELECT XMLQuery('for $e in doc("/public/emps.xml")/emps/emp
let $d :=
doc("/public/depts.xml")//dept[@deptno = $e/@deptno]/@dname
where $e/@salary > 100000
order by $e/@empno
return '
RETURNING CONTENT) FROM DUAL;
XMLQUERY('FOR$EINDOC("/PUBLIC/EMPS.XML")/EMPS/EMPLET$D:=DOC("/PUBLIC/DEPTS.XML")
-------------------------------------------------------------------------------
1 row selected.

In Example 5–3, the various FLWOR clauses perform these operations:
■

■

■

■

■

■

for iterates over the emp elements in /public/emps.xml, binding variable $e
to the value of each such element, in turn. That is, it iterates over a general list of
employees, binding $e to each employee.
let binds variable $d to a sequence consisting of all of the values of dname
attributes of those dept elements in /public/emps.xml whose deptno
attributes have the same value as the deptno attribute of element $e (this is a join
operation). That is, it binds $d to the names of all of the departments that have the
same department number as the department of employee $e. (It so happens that
the dname value is unique for each deptno value in depts.xml.) Note that,
unlike for, let never iterates over values; $d is bound only once in this example.
Together, for and let produce a stream of tuples ($e, $d), where $e represents
an employee and $d represents the names of all of the departments to which that
employee belongs—in this case, the unique name of the employee's unique
department.
where filters this tuple stream, keeping only tuples with employees whose salary
is greater than 100,000.
order by sorts the filtered tuple stream by employee number, empno (in
ascending order, by default).
return constructs emp elements, one for each tuple. Attributes ename and dept
of these elements are constructed using attribute ename from the input and $d,
respectively. Note that the element and attribute names emp and ename in the
output have no necessary connection with the same names in the input document
emps.xml.

Using XQuery with Oracle XML DB 5-17

XMLQUERY and XMLTABLE Examples

Example 5–4 also uses each of the FLWOR-expression clauses. It shows the use of
XQuery functions doc, count, avg, and integer, which are in the namespace for
built-in XQuery functions, http://www.w3.org/2003/11/xpath-functions.
This namespace is bound to the prefix fn.
Example 5–4 FLOWR Expression using Built-In Functions
SELECT XMLQuery('for $d in fn:doc("/public/depts.xml")/depts/dept/@deptno
let $e := fn:doc("/public/emps.xml")/emps/emp[@deptno = $d]
where fn:count($e) > 1
order by fn:avg($e/@salary) descending
return
{$d,
{fn:count($e)},
{xs:integer(fn:avg($e/@salary))}}
'
RETURNING CONTENT) FROM DUAL;
XMLQUERY('FOR$DINFN:DOC("/PUBLIC/DEPTS.XML")/DEPTS/DEPT/@DEPTNOLET$E:=FN:DOC("/P
-------------------------------------------------------------------------------2165500
1 row selected.

In Example 5–4, the various FLWOR clauses perform these operations:
■

■

■

■
■

■

for iterates over deptno attributes in input document /public/depts.xml,
binding variable $d to the value of each such attribute, in turn.
let binds variable $e to a sequence consisting of all of the emp elements in input
document /public/emps.xml whose deptno attributes have value $d (this is a
join operation).
Together, for and let produce a stream of tuples ($d, $e), where $d represents a
department number and $e represents the set of employees in that department.
where filters this tuple stream, keeping only tuples with more than one employee.
order by sorts the filtered tuple stream by average salary in descending order.
The average is computed by applying XQuery function avg (in namespace fn) to
the values of attribute salary, which is attached to the emp elements of $e.
return constructs big-dept elements, one for each tuple produced by order
by. The text() node of big-dept contains the department number, bound to
$d. A headcount child element contains the number of employees, bound to $e,
as determined by XQuery function count. An avgsal child element contains the
computed average salary.

Querying Table or View Data using XQuery
This section presents examples of using XQuery to query relational data as if it were
XML data.
Example 5–5 uses Oracle XQuery function fn:collection in a FLWOR expression
to query two relational tables, regions and countries. Both tables belong to sample
database schema HR. The example also passes scalar SQL value Asia to XQuery
variable $regionname. Any SQL expression can be evaluated to produce a value
passed to XQuery using PASSING. In this case, the value comes from a SQL*Plus
variable, REGION. You must cast the value to the scalar SQL data type expected, in this
case, VARCHAR2(40).

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Example 5–5 Querying Relational Tables as XML
DEFINE REGION = 'Asia'
SELECT XMLQuery('for $i in fn:collection("oradb:/HR/REGIONS"),
$j in fn:collection("oradb:/HR/COUNTRIES")
where $i/ROW/REGION_ID = $j/ROW/REGION_ID
and $i/ROW/REGION_NAME = $regionname
return $j'
PASSING CAST('®ION' AS VARCHAR2(40)) AS "regionname"
RETURNING CONTENT) AS asian_countries
FROM DUAL;

This produces the following result. (The result is shown here pretty-printed, for
clarity.)
ASIAN_COUNTRIES
----------------------------------------
AU
Australia
3


CN
China
3


HK
HongKong
3


IN
India
3


JP
Japan
3


SG
Singapore
3

1 row selected.

In Example 5–5, the various FLWOR clauses perform these operations:
■

for iterates over sequences of XML elements returned by calls to
fn:collection. In the first call, each element corresponds to a row of relational
table hr.regions and is bound to variable $i. Similarly, in the second call to
fn:collection, $j is bound to successive rows of table hr.countries. Since
regions and countries are not XMLType tables, the top-level element
corresponding to a row in each table is ROW (a wrapper element). Iteration over the
row elements is unordered.

Using XQuery with Oracle XML DB 5-19

XMLQUERY and XMLTABLE Examples

■

■

where filters the rows from both tables, keeping only those pairs of rows whose
region_id is the same for each table (it performs a join on region_id) and
whose region_name is Asia.
return returns the filtered rows from table hr.countries as an XML document
containing XML fragments with ROW as their top-level element.

Example 5–6 uses fn:collection within nested FLWOR expressions to query
relational data.
Example 5–6 Using Relational Data in a Nested FLWOR Query
CONNECT hr
Enter password: password
Connected.
GRANT SELECT ON LOCATIONS TO OE
/
CONNECT oe
Enter password: password
Connected.
SELECT XMLQuery(
'for $i in fn:collection("oradb:/OE/WAREHOUSES")/ROW
return 

{for $j in fn:collection("oradb:/HR/LOCATIONS")/ROW
where $j/LOCATION_ID eq $i/LOCATION_ID
return ($j/STREET_ADDRESS, $j/CITY, $j/STATE_PROVINCE)}

'
RETURNING CONTENT) FROM DUAL;

This query is an example of using nested FLWOR expressions. It accesses relational
table warehouses, which is in sample database schema oe, and relational table
locations, which is in sample database schema HR. To run this example as user oe,
you must first connect as user hr and grant permission to user oe to perform SELECT
operations on table locations.
This produces the following result. (The result is shown here pretty-printed, for
clarity.)
XMLQUERY('FOR$IINFN:COLLECTION("ORADB:/OE/WAREHOUSES")/ROWRETURN

2014 Jabberwocky Rd
Southlake
Texas




2011 Interiors Blvd
South San Francisco
California




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2007 Zagora St
South Brunswick
New Jersey




2004 Charade Rd
Seattle
Washington




147 Spadina Ave
Toronto
Ontario




12-98 Victoria Street
Sydney
New South Wales




Mariano Escobedo 9991
Mexico City
Distrito Federal,




40-5-12 Laogianggen
Beijing




1298 Vileparle (E)
Bombay
Maharashtra


1 row selected.

In Example 5–6, the various FLWOR clauses perform these operations:
■

The outer for iterates over the sequence of XML elements returned by
fn:collection: each element corresponds to a row of relational table
oe.warehouses and is bound to variable $i. Since warehouses is not an
XMLType table, the top-level element corresponding to a row is ROW. The iteration
over the row elements is unordered.

Using XQuery with Oracle XML DB 5-21

XMLQUERY and XMLTABLE Examples

■

■

■

■

The inner for iterates, similarly, over a sequence of XML elements returned by
fn:collection: each element corresponds to a row of relational table
hr.locations and is bound to variable $j.
where filters the tuples ($i, $j), keeping only those whose location_id child is
the same for $i and $j (it performs a join on location_id).
The inner return constructs an XQuery sequence of elements STREET_ADDRESS,
CITY, and STATE_PROVINCE, all of which are children of locations-table ROW
element $j; that is, they are the values of the locations-table columns of the same
name.
The outer return wraps the result of the inner return in a Location element,
and wraps that in a Warehouse element. It provides the Warehouse element with
an id attribute whose value comes from the warehouse_id column of table
warehouses.
See Also:

Example 5–15 for the execution plan of Example 5–6

Example 5–7 uses SQL/XML function XMLTable to decompose the result of an
XQuery query to produce virtual relational data. The XQuery expression used in this
example is identical to the one used in Example 5–6; the result of evaluating the
XQuery expression is a sequence of Warehouse elements. Function XMLTable
produces a virtual relational table whose rows are those Warehouse elements. More
precisely, the value of pseudocolumn COLUMN_VALUE for each virtual-table row is an
XML fragment (of type XMLType) with a single Warehouse element.
Example 5–7 Querying a Relational Table as XML using XMLTable
SELECT *
FROM XMLTable(
'for $i in fn:collection("oradb:/OE/WAREHOUSES")/ROW
return 

{for $j in fn:collection("oradb:/HR/LOCATIONS")/ROW
where $j/LOCATION_ID eq $i/LOCATION_ID
return ($j/STREET_ADDRESS, $j/CITY, $j/STATE_PROVINCE)}

');

This produces the same result as Example 5–6, except that each Warehouse element is
output as a separate row, instead of all Warehouse elements being output together in
a single row.
COLUMN_VALUE
-------------------------------------------------------

2014 Jabberwocky Rd
Southlake
Texas




2011 Interiors Blvd
South San Francisco
California



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. . .
9 rows selected.

See Also:

Example 5–16 for the execution plan of Example 5–7

Using XQuery with XMLType Data
This section presents examples of using XQuery with XMLType relational data.
The query in Example 5–8 passes an XMLType column, warehouse_spec, as context
item to XQuery, using function XMLQuery with the PASSING clause. It constructs a
Details element for each of the warehouses whose area is greater than 80,000:
/Warehouse/ Area > 80000.
Example 5–8 Querying an XMLType Column using XMLQuery PASSING Clause
SELECT warehouse_name,
XMLQuery(
'for $i in /Warehouse
where $i/Area > 80000
return 


{if ($i/RailAccess = "Y") then "true" else "false"}

'
PASSING warehouse_spec RETURNING CONTENT) big_warehouses
FROM oe.warehouses;

This produces the following output:
WAREHOUSE_NAME
-------------BIG_WAREHOUSES
-------------Southlake, Texas

San Francisco

New Jersey
false
Seattle, Washington
true
Toronto

Sydney

Mexico City

Beijing

Bombay

Using XQuery with Oracle XML DB 5-23

XMLQUERY and XMLTABLE Examples

9 rows selected.

In Example 5–8, function XMLQuery is applied to the warehouse_spec column in
each row of table warehouses. The various FLWOR clauses perform these operations:
■

■

■

for iterates over the Warehouse elements in each row of column warehouse_
spec (the passed context item): each such element is bound to variable $i, in turn.
The iteration is unordered.
where filters the Warehouse elements, keeping only those whose Area child has
a value greater than 80,000.
return constructs an XQuery sequence of Details elements, each of which
contains a Docks and a Rail child elements. The num attribute of the constructed
Docks element is set to the text() value of the Docks child of Warehouse. The
text() content of Rail is set to true or false, depending on the value of the
RailAccess attribute of element Warehouse.

The SELECT statement in Example 5–8 applies to each row in table warehouses. The
XMLQuery expression returns the empty sequence for those rows that do not match the
XQuery expression. Only the warehouses in New Jersey and Seattle satisfy the XQuery
query, so they are the only warehouses for which 
...
 is
returned.
Example 5–9 uses SQL/XML function XMLTable to query an XMLType table,
oe.purchaseorder, which contains XML Schema-based data. It uses the PASSING
clause to provide the purchaseorder table as the context item for the
XQuery-expression argument to XMLTable. Pseudocolumn COLUMN_VALUE of the
resulting virtual table holds a constructed element, A10po, which contains the
Reference information for those purchase orders whose CostCenter element has
value A10 and whose User element has value SMCCAIN. The query performs a join
between the virtual table and database table purchaseorder.
Example 5–9 Using XMLTABLE with XML Schema-Based Data
SELECT xtab.COLUMN_VALUE
FROM purchaseorder, XMLTable('for $i in /PurchaseOrder
where $i/CostCenter eq "A10"
and $i/User eq "SMCCAIN"
return '
PASSING OBJECT_VALUE) xtab;
COLUMN_VALUE
--------------------------------------------------









10 rows selected.

The PASSING clause of function XMLTable passes the OBJECT_VALUE of XMLType
table purchaseorder, to serve as the XPath context. The XMLTable expression thus

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depends on the purchaseorder table. Because of this, table purchaseorder must
appear before the XMLTable expression in the FROM list. This is a general requirement
in any situation involving data dependence.
Note: Whenever a PASSING clause refers to a column of an
XMLType table in a query, that table must appear before the
XMLTable expression in the query FROM list. This is because the
XMLTable expression depends on the XMLType table—a left lateral
(correlated) join is needed, to ensure a one-to-many (1:N) relationship
between the XMLType table row accessed and the rows generated
from it by XMLTable.

Example 5–10 is similar to Example 5–9 in its effect. It uses XMLQuery, instead of
XMLTable, to query oe.purchaseorder. These two examples differ in their
treatment of the empty sequences returned by the XQuery expression. In Example 5–9,
these empty sequences are not joined with the purchaseorder table, so the overall
SQL-query result set has only ten rows. In Example 5–10, these empty sequences are
part of the overall result set of the SQL query, which contains 132 rows, one for each of
the rows in table purchaseorder. All but ten of those rows are empty, and show up
in the output as empty lines. To save space here, those empty lines have been
removed.
Example 5–10

Using XMLQUERY with Schema-Based Data

SELECT XMLQuery('for $i in /PurchaseOrder
where $i/CostCenter eq "A10"
and $i/User eq "SMCCAIN"
return '
PASSING OBJECT_VALUE
RETURNING CONTENT)
FROM purchaseorder;
XMLQUERY('FOR$IIN/PURCHASEORDERWHERE$I/COSTCENTEREQ"A10"AND$I/USEREQ"SMCCAIN"RET
-------------------------------------------------------------------------------









132 rows selected.

See Also:

Example 5–17 for the execution plan of Example 5–10

Example 5–11 uses XMLTable clauses PASSING and COLUMNS. The XQuery
expression iterates over top-level PurchaseOrder elements, constructing a PO
element for each purchase order with cost center A10. The resulting PO elements are
then passed to XMLTable for processing.
Example 5–11

Using XMLTABLE with PASSING and COLUMNS Clauses

SELECT xtab.poref, xtab.priority, xtab.contact

Using XQuery with Oracle XML DB 5-25

XMLQUERY and XMLTABLE Examples

FROM purchaseorder,
XMLTable('for $i in /PurchaseOrder
let $spl := $i/SpecialInstructions
where $i/CostCenter eq "A10"
return 
{$i/Reference}
{if ($spl eq "Next Day Air" or $spl eq "Expedite") then
Fastest
else if ($spl eq "Air Mail") then
Fast
else ()}
{$i/Requestor}
'
PASSING OBJECT_VALUE
COLUMNS poref
VARCHAR2(20) PATH 'Ref',
priority VARCHAR2(8) PATH 'Type' DEFAULT 'Regular',
contact VARCHAR2(20) PATH 'Name') xtab;
POREF
-------------------SKING-20021009123336
SMCCAIN-200210091233
SMCCAIN-200210091233
JCHEN-20021009123337
JCHEN-20021009123337
SKING-20021009123337
SMCCAIN-200210091233
JCHEN-20021009123338
SMCCAIN-200210091233
SKING-20021009123335
SMCCAIN-200210091233
SKING-20021009123336
SMCCAIN-200210091233
SKING-20021009123336
SKING-20021009123336
SMCCAIN-200210091233
JCHEN-20021009123335
SKING-20021009123336
JCHEN-20021009123336
SKING-20021009123336
SMCCAIN-200210091233
SKING-20021009123337
SKING-20021009123338
SMCCAIN-200210091233
JCHEN-20021009123337
JCHEN-20021009123337
JCHEN-20021009123337
SKING-20021009123337
JCHEN-20021009123337
SKING-20021009123337
SKING-20021009123337
SMCCAIN-200210091233

PRIORITY
-------Fastest
Regular
Fastest
Fastest
Regular
Regular
Regular
Regular
Regular
Regular
Regular
Regular
Fast
Fastest
Fastest
Regular
Regular
Regular
Regular
Regular
Regular
Regular
Fastest
Regular
Regular
Regular
Regular
Regular
Regular
Regular
Regular
Fast

CONTACT
-------------------Steven A. King
Samuel B. McCain
Samuel B. McCain
John Z. Chen
John Z. Chen
Steven A. King
Samuel B. McCain
John Z. Chen
Samuel B. McCain
Steven X. King
Samuel B. McCain
Steven A. King
Samuel B. McCain
Steven A. King
Steven A. King
Samuel B. McCain
John Z. Chen
Steven A. King
John Z. Chen
Steven A. King
Samuel B. McCain
Steven A. King
Steven A. King
Samuel B. McCain
John Z. Chen
John Z. Chen
John Z. Chen
Steven A. King
John Z. Chen
Steven A. King
Steven A. King
Samuel B. McCain

32 rows selected.

In Example 5–11, data from the children of PurchaseOrder is used to construct the
children of PO, which are Ref, Type, and Name. The content of Type is taken from the
content of /PurchaseOrder/SpecialInstructions, but the classes of
SpecialInstructions are divided up differently for Type.

5-26 Oracle XML DB Developer's Guide

XMLQUERY and XMLTABLE Examples

Function XMLTable breaks up the result of XQuery evaluation, returning it as three
VARCHAR2 columns of a virtual table: poref, priority, and contact. The DEFAULT
clause is used to supply a default priority of Regular.
In Example 5–12, SQL/XML function XMLTable is used to break up the XML data in
an XMLType collection element, LineItem, into separate columns of a virtual table.
Example 5–12
XMLTABLE

Decomposing XML Collection Elements into Relational Data using

SELECT lines.lineitem, lines.description, lines.partid,
lines.unitprice, lines.quantity
FROM purchaseorder,
XMLTable('for $i in /PurchaseOrder/LineItems/LineItem
where $i/@ItemNumber >= 8
and $i/Part/@UnitPrice > 50
and $i/Part/@Quantity > 2
return $i'
PASSING OBJECT_VALUE
COLUMNS lineitem
NUMBER
PATH '@ItemNumber',
description VARCHAR2(30) PATH 'Description',
partid
NUMBER
PATH 'Part/@Id',
unitprice
NUMBER
PATH 'Part/@UnitPrice',
quantity
NUMBER
PATH 'Part/@Quantity') lines;
LINEITEM
-------11
22
11
16
8
12
18
24
14
10
17
16
13
10
12
12
13

DESCRIPTION
PARTID UNITPRICE QUANTITY
------------------------------ ------------- --------- -------Orphic Trilogy
37429148327
80
3
Dreyer Box Set
37429158425
80
4
Dreyer Box Set
37429158425
80
3
Dreyer Box Set
37429158425
80
3
Dreyer Box Set
37429158425
80
3
Brazil
37429138526
60
3
Eisenstein: The Sound Years
37429149126
80
4
Dreyer Box Set
37429158425
80
3
Dreyer Box Set
37429158425
80
4
Brazil
37429138526
60
3
Eisenstein: The Sound Years
37429149126
80
3
Orphic Trilogy
37429148327
80
4
Orphic Trilogy
37429148327
80
4
Brazil
37429138526
60
4
Eisenstein: The Sound Years
37429149126
80
3
Dreyer Box Set
37429158425
80
4
Dreyer Box Set
37429158425
80
4

17 rows selected.

See Also:
■
■

Example 5–18 for the execution plan of Example 5–12
"Breaking Up Multiple Levels of XML Data" on page 3-49, for an
example of applying XMLTable to multiple document levels
(multilevel chaining)

Using Namespaces with XQuery
You can use the XQuery declare namespace declaration in the prolog of an XQuery
expression to define a namespace prefix. You can use declare default namespace
to establish the namespace as the default namespace for the expression.

Using XQuery with Oracle XML DB 5-27

XMLQUERY and XMLTABLE Examples

Be aware of the following pitfall, if you use SQL*Plus: If the semicolon (;) at the end of
a namespace declaration terminates a line, SQL*Plus interprets it as a SQL terminator.
To avoid this, you can do one of the following:
■

Place the text that follows the semicolon on the same line.

■

Place a comment, such as (: :), after the semicolon, on the same line.

■

Turn off the recognition of the SQL terminator with SQL*Plus command SET
SQLTERMINATOR.

Example 5–13 illustrates use of a namespace declaration in an XQuery expression.
Example 5–13

Using XMLQUERY with a Namespace Declaration

SELECT XMLQuery('declare namespace e = "http://example.com";
ERROR:
ORA-01756: quoted string not properly terminated
for $i in doc("/public/empsns.xml")/e:emps/e:emp
SP2-0734: unknown command beginning "for $i in ..." - rest of line ignored.
...
-- This works - do not end the line with ";".
SELECT XMLQuery('declare namespace e = "http://example.com"; for
$i in doc("/public/empsns.xml")/e:emps/e:emp
let $d :=
doc("/public/depts.xml")//dept[deptno=$i/@deptno]/@dname
where $i/@salary > 100000
order by $i/@empno
return '
RETURNING CONTENT) FROM DUAL;
XMLQUERY('DECLARENAMESPACEE="HTTP://EXAMPLE.COM";FOR$IINDOC("/PUBLIC/EMPSNS.XML"
-------------------------------------------------------------------------------
-- This works too - add a comment after the ";".
SELECT XMLQuery('declare namespace e = "http://example.com"; (: :)
for $i in doc("/public/empsns.xml")/e:emps/e:emp
let $d := doc("/public/depts.xml")//dept[deptno=$i/@deptno]/@dname
where $i/@salary > 100000
order by $i/@empno
return '
RETURNING CONTENT) FROM DUAL;
XMLQUERY('DECLARENAMESPACEE="HTTP://EXAMPLE.COM";(::)FOR$IINDOC("/PUBLIC/EMPSNS.
-------------------------------------------------------------------------------
1 row selected.
-- This works too - tell SQL*Plus to ignore the ";".
SET SQLTERMINATOR OFF
SELECT XMLQuery('declare namespace e = "http://example.com";
for $i in doc("/public/empsns.xml")/e:emps/e:emp
let $d :=
doc("/public/depts.xml")//dept[deptno=$i/@deptno]/@dname
where $i/@salary > 100000
order by $i/@empno
return '
5-28 Oracle XML DB Developer's Guide

Performance Tuning for XQuery

RETURNING CONTENT) FROM DUAL
/
XMLQUERY('DECLARENAMESPACEE="HTTP://EXAMPLE.COM";FOR$IINDOC("/PUBLIC/EMPSNS.XML"
-------------------------------------------------------------------------------

An XQuery namespace declaration has no effect outside of its XQuery expression. To
declare a namespace prefix for use in an XMLTable expression outside of the XQuery
expression, use the XMLNAMESPACES clause. This clause also covers the XQuery
expression argument to XMLTable, eliminating the need for a separate declaration in
the XQuery prolog.
In Example 5–14, XMLNAMESPACES is used to define the prefix e for the namespace
http://example.com. This namespace is used in the COLUMNS clause and the
XQuery expression of the XMLTable expression.
Example 5–14

Using XMLTABLE with the XMLNAMESPACES Clause

SELECT * FROM XMLTable(XMLNAMESPACES ('http://example.com' AS "e"),
'for $i in doc("/public/empsns.xml")
return $i/e:emps/e:emp'
COLUMNS name VARCHAR2(6) PATH '@ename',
id
NUMBER
PATH '@empno');

This produces the following result:
NAME
ID
------ ---------John
1
Jack
2
Jill
3
3 rows selected.

It is the presence of qualified names e:ename and e:empno in the COLUMNS clause
that necessitates using the XMLNAMESPACES clause. Otherwise, a prolog namespace
declaration (declare namespace e = "http://example.com") would suffice
for the XQuery expression itself.
Because the same namespace is used throughout the XMLTable expression, a default
namespace could be used: XMLNAMESPACES (DEFAULT
'http://example.com'). The qualified name $i/e:emps/e:emp could then be
written without an explicit prefix: $i/emps/emp.

Performance Tuning for XQuery
A SQL query that involves XQuery expressions can often be rewritten (optimized) in
one or more ways. This optimization is referred to as XML query rewrite or
optimization. XPath expressions are a proper subset of XQuery expressions.
XPath rewrite is a subset of XML query rewrite that involves rewriting queries that
involve XPath expressions. XPath rewrite includes XMLIndex optimizations,
streaming evaluation of binary XML, and rewrite to underlying object-relational or
relational structures in the case of structured storage or XMLType views over relational
data.
Just as query tuning can improve SQL performance, so it can improve XQuery
performance. You tune XQuery performance by choosing appropriate XML storage
models and indexes.
Using XQuery with Oracle XML DB 5-29

Performance Tuning for XQuery

As with database queries generally, you determine whether tuning is required by
examining the execution plan for a query. If the plan is not optimal, then consult the
following documentation for specific tuning information:
■
■

For structured storage: Chapter 8, "XPath Rewrite for Structured Storage"
For unstructured storage and binary XML storage: Chapter 6, "Indexing XMLType
Data"

In addition, be aware that the following expressions can be expensive to process, so
they might add performance overhead when processing large volumes of data:
■

■

■

SQL expressions that use the following Oracle SQL functions, which accept XPath
expression arguments:
–

appendChildXML (use insertChildXMLAfter instead)

–

insertXMLAfter (use insertChildXMLAfter instead)

–

insertXMLBefore (use insertChildXMLBefore instead)

XQuery expressions that use the following axes (use forward and descendent axes
instead):
–

ancestor

–

ancestor-or-self

–

descendant-or-self

–

following

–

following-sibling

–

namespace

–

parent

–

preceding

–

preceding-sibling

XQuery expressions that involve node identity (for example, using the
order-comparison operators << and >>)
See Also:

"Oracle XML DB Support for XQuery" on page 5-42

The following sections present the execution plans for some of the examples shown
earlier in this chapter, to indicate how they are executed.
■

■

"XQuery Optimization over Relational Data" on page 5-31: examples with XQuery
expressions that target XML data created on the fly using fn:collection
together with URI scheme oradb.
"XQuery Optimization over XML Schema-Based XMLType Data" on page 5-32:
examples with XQuery expressions that target an XML schema-based XMLType
table stored object-relationally

5-30 Oracle XML DB Developer's Guide

Performance Tuning for XQuery

See Also:
■
■

■

Chapter 8, "XPath Rewrite for Structured Storage"
Chapter 6, "Indexing XMLType Data" for information about using
XMLIndex
"How Oracle XML DB Processes XMLType Methods and SQL
Functions" on page 3-58 for information about streaming
evaluation of binary XML data

Rule-Based and Cost-Based XQuery Optimization
Several competing optimization possibilities can exist for queries with XQuery
expressions, depending on various factors such as the XMLType storage model and
indexing that are used.
By default, Oracle XML DB follows a prioritized set of rules to determine which of the
possible optimizations should be used for any given query and context. This behavior
is referred to as rule-based XML query rewrite.
Alternatively, Oracle XML DB can use cost-based XML query rewrite. In this mode,
Oracle XML DB estimates the performance of the various XML optimization
possibilities for a given query and chooses the combination that is expected to be most
performant.
You can impose cost-based optimization for a given SQL statement by using the
optimizer hint /*+ COST_XML_QUERY_REWRITE */.

XQuery Optimization over Relational Data
Example 5–15 shows the optimization of XMLQuery over relational data accessed as
XML. Example 5–16 shows the optimization of XMLTable in the same context.
Example 5–15

Optimization of XMLQuery over Relational Data

Here again is the query of Example 5–6, together with its execution plan, which shows
that the query has been optimized.
SELECT XMLQuery(
'for $i in fn:collection("oradb:/OE/WAREHOUSES")/ROW
return 

{for $j in fn:collection("oradb:/HR/LOCATIONS")/ROW
where $j/LOCATION_ID eq $i/LOCATION_ID
return ($j/STREET_ADDRESS, $j/CITY, $j/STATE_PROVINCE)}

'
RETURNING CONTENT) FROM DUAL;
PLAN_TABLE_OUTPUT
-------------------------------------------------------------------------------------------Plan hash value: 3341889589
------------------------------------------------------------------------------------------| Id | Operation
| Name
| Rows | Bytes | Cost (%CPU)| Time
|
------------------------------------------------------------------------------------------|
0 | SELECT STATEMENT
|
|
1 |
|
2
(0)| 00:00:01 |
|
1 | SORT AGGREGATE
|
|
1 |
41 |
|
|
|
2 |
TABLE ACCESS BY INDEX ROWID| LOCATIONS |
1 |
41 |
1
(0)| 00:00:01 |
|* 3 |
INDEX UNIQUE SCAN
| LOC_ID_PK |
1 |
|
0
(0)| 00:00:01 |
|
4 | SORT AGGREGATE
|
|
1 |
6 |
|
|

Using XQuery with Oracle XML DB 5-31

Performance Tuning for XQuery

|
5 |
TABLE ACCESS FULL
| WAREHOUSES |
9 |
54 |
2
(0)| 00:00:01 |
|
6 | FAST DUAL
|
|
1 |
|
2
(0)| 00:00:01 |
------------------------------------------------------------------------------------------Predicate Information (identified by operation id):
--------------------------------------------------3 - access("LOCATION_ID"=:B1)
18 rows selected.

Example 5–16

Optimization of XMLTable over Relational Data

Here again is the query of Example 5–7, together with its execution plan, which shows
that the query has been optimized.
SELECT *
FROM XMLTable(
'for $i in fn:collection("oradb:/OE/WAREHOUSES")/ROW
return 

{for $j in fn:collection("oradb:/HR/LOCATIONS")/ROW
where $j/LOCATION_ID eq $i/LOCATION_ID
return ($j/STREET_ADDRESS, $j/CITY, $j/STATE_PROVINCE)}

');
PLAN_TABLE_OUTPUT
------------------------------------------------------------------------------------------Plan hash value: 1021775546
------------------------------------------------------------------------------------------| Id | Operation
| Name
| Rows | Bytes | Cost (%CPU)| Time
|
------------------------------------------------------------------------------------------|
0 | SELECT STATEMENT
|
|
9 |
54 |
2
(0)| 00:00:01 |
|
1 | SORT AGGREGATE
|
|
1 |
41 |
|
|
|
2 |
TABLE ACCESS BY INDEX ROWID| LOCATIONS |
1 |
41 |
1
(0)| 00:00:01 |
|* 3 |
INDEX UNIQUE SCAN
| LOC_ID_PK |
1 |
|
0
(0)| 00:00:01 |
|
4 | TABLE ACCESS FULL
| WAREHOUSES |
9 |
54 |
2
(0)| 00:00:01 |
------------------------------------------------------------------------------------------Predicate Information (identified by operation id):
--------------------------------------------------3 - access("LOCATION_ID"=:B1)
16 rows selected.

XQuery Optimization over XML Schema-Based XMLType Data
Example 5–17 shows the optimization of XMLQuery over an XML schema-based
XMLType table. Example 5–18 shows the optimization of XMLTable in the same
context.
Example 5–17

Optimization of XMLQuery with Schema-Based XMLType Data

Here again is the query of Example 5–10, together with its execution plan, which
shows that the query has been optimized.
SELECT XMLQuery('for $i in /PurchaseOrder
where $i/CostCenter eq "A10"
and $i/User eq "SMCCAIN"
5-32 Oracle XML DB Developer's Guide

Performance Tuning for XQuery

return '
PASSING OBJECT_VALUE
RETURNING CONTENT)
FROM purchaseorder;
PLAN_TABLE_OUTPUT
------------------------------------------------------------------------------------Plan hash value: 3611789148
------------------------------------------------------------------------------------| Id | Operation
| Name
| Rows | Bytes | Cost (%CPU)| Time
|
------------------------------------------------------------------------------------|
0 | SELECT STATEMENT
|
|
1 |
530 |
5
(0)| 00:00:01 |
|
1 | SORT AGGREGATE
|
|
1 |
|
|
|
|* 2 |
FILTER
|
|
|
|
|
|
|
3 |
FAST DUAL
|
|
1 |
|
2
(0)| 00:00:01 |
|* 4 |
TABLE ACCESS FULL| PURCHASEORDER |
1 |
530 |
5
(0)| 00:00:01 |
------------------------------------------------------------------------------------Predicate Information (identified by operation id):
--------------------------------------------------2 - filter(:B1='SMCCAIN' AND :B2='A10')
4 - filter(SYS_CHECKACL("ACLOID","OWNERID",xmltype('
'))=1)
22 rows selected.
Example 5–18

Optimization of XMLTable with Schema-Based XMLType Data

Here again is the query of Example 5–12, together with its execution plan, which
shows that the query has been optimized. The XQuery result is never materialized.
Instead, the underlying storage columns for the XML collection element LineItem are
used to generate the overall result set.
SELECT lines.lineitem, lines.description, lines.partid,
lines.unitprice, lines.quantity
FROM purchaseorder,
XMLTable('for $i in /PurchaseOrder/LineItems/LineItem
where $i/@ItemNumber >= 8
and $i/Part/@UnitPrice > 50
and $i/Part/@Quantity > 2
return $i'
PASSING OBJECT_VALUE
COLUMNS lineitem
NUMBER
PATH '@ItemNumber',
description VARCHAR2(30) PATH 'Description',
partid
NUMBER
PATH 'Part/@Id',
unitprice
NUMBER
PATH 'Part/@UnitPrice',
quantity
NUMBER
PATH 'Part/@Quantity') lines;
----------------------------------------------------------------------------------------------| Id | Operation
| Name
| Rows | Bytes | Cost (%CPU)| Time
|
----------------------------------------------------------------------------------------------|
0 | SELECT STATEMENT
|
|
4 |
384 |
7
(0)| 00:00:01 |
|
1 | NESTED LOOPS
|
|
|
|
|
|
|
2 |
NESTED LOOPS
|
|
4 |
384 |
7
(0)| 00:00:01 |
|* 3 |
TABLE ACCESS FULL
| PURCHASEORDER |
1 |
37 |
5
(0)| 00:00:01 |
Using XQuery with Oracle XML DB 5-33

Performance Tuning for XQuery

|* 4 |
INDEX RANGE SCAN
| SYS_C005478
|
17 |
|
1
(0)| 00:00:01 |
|* 5 |
TABLE ACCESS BY INDEX ROWID| LINEITEM_TABLE |
3 |
177 |
2
(0)| 00:00:01 |
----------------------------------------------------------------------------------------------Predicate Information (identified by operation id):
--------------------------------------------------3 - filter(SYS_CHECKACL("ACLOID","OWNERID",xmltype(''))=1)
4 - access("NESTED_TABLE_ID"="PURCHASEORDER"."SYS_NC0003400035$")
5 - filter("SYS_NC00013$">50 AND "SYS_NC00012$">2 AND "ITEMNUMBER">=8 AND
"SYS_NC_TYPEID$" IS NOT NULL)
25 rows selected.

This example traverses table oe.purchaseorder completely. The XMLTable
expression is evaluated for each purchase-order document. It is more efficient to have
the XMLTable expression, not the purchaseorder table, drive the SQL-query
execution.
Although the XQuery expression has been rewritten to relational expressions, you can
improve this optimization by creating an index on the underlying relational data—you
can optimize this query in the same way that you would optimize a purely SQL query.
That is always the case with XQuery in Oracle XML DB: the optimization techniques
you use are the same as those you use in SQL.
The UnitPrice attribute of collection element LineItem is an appropriate index
target. The governing XML schema specifies that an ordered collection table (OCT) is
used to store the LineItem elements.
However, the name of this OCT was generated by Oracle XML DB when the XML
purchase-order documents were decomposed as XML schema-based data. Instead of
using table purchaseorder from sample database schema HR, you could manually
create a new purchaseorder table (in a different database schema) with the same
properties and same data, but having OCTs with user-friendly names. Refer to
Example 3–13 on page 3-28 for how to do this.
Assuming that a purchaseorder table has been created as in Example 3–13, the
following statement creates the appropriate index:
CREATE INDEX unitprice_index ON lineitem_table("PART"."UNITPRICE");

With this index defined, the query of Example 5–12 results in the following execution
plan, which shows that the XMLTable expression has driven the overall evaluation.
PLAN_TABLE_OUTPUT
---------------------------------------------------------------------------------------Plan hash value: 1578014525
---------------------------------------------------------------------------------------| Id | Operation
| Name
| Rows | Bytes | Cost (%CPU)| Time
|
---------------------------------------------------------------------------------------|
0 | SELECT STATEMENT
|
|
3 |
624 |
8
(0)| 00:00:01 |
|
1 | NESTED LOOPS
|
|
3 |
624 |
8
(0)| 00:00:01 |
|* 2 |
INDEX UNIQUE SCAN| SYS_IOT_TOP_49323 |
3 |
564 |
5
(0)| 00:00:01 |
|* 3 |
INDEX RANGE SCAN| UNITPRICE_INDEX
|
20 |
|
2
(0)| 00:00:01 |
|* 4 |
INDEX UNIQUE SCAN| SYS_C004411
|
1 |
|
0
(0)| 00:00:01 |

5-34 Oracle XML DB Developer's Guide

Performance Tuning for XQuery

---------------------------------------------------------------------------------------Predicate Information (identified by operation id):
--------------------------------------------------2 - access("SYS_NC00013$">50)
filter("ITEMNUMBER">=8 AND "SYS_NC00012$">2)
3 - access("SYS_NC00013$">50)
4 - access("NESTED_TABLE_ID"="PURCHASEORDER"."SYS_NC0003400035$")
Note
----- dynamic sampling used for this statement
23 rows selected.

Diagnosing XQuery Optimization: XMLOptimizationCheck
You can examine an execution plan for your SQL code to determine whether XQuery
optimization occurs or the plan is instead suboptimal. In the latter case, a note such as
the following appears immediately after the plan:
Unoptimized XML construct detected (enable XMLOptimizationCheck
for more information)

You can also compare the execution plan output with the plan output that you see
after you use the optimizer hint NO_XML_QUERY_REWRITE, which turns off XQuery
optimization.
In addition, you can use the SQL*Plus SET command with system variable
XMLOptimizationCheck to turn on an XML diagnosability mode for SQL:
SET XMLOptimizationCheck ON

When this mode is on, the plan of execution is automatically checked for XQuery
optimization, and if the plan is suboptimal then an error is raised and diagnostic
information is written to the trace file indicating which operators are not rewritten.
The main advantage of XMLOptimizationCheck is that it brings a potential problem
to your attention immediately. For this reason, you might find it preferable to leave it
turned on at all times. Then, if an application change or a database change for some
reason prevents a SQL operation from rewriting, execution is stopped instead of
performance being negatively impacted without your being aware of the cause.
Note:
■

■

You can use event 19027 with level 8192 (0x2000) to dump a trace
that indicates why a particular expression is not rewritten.
XMLOptimizationCheck was not available prior to Oracle
Database 11g Release 2 (11.2.0.2). Users of older releases directly
manipulated event 19201 to obtain XQuery optimization
information.

"Turning Off Use of XMLIndex" on page 6-30 for
information about optimizer hint NO_XML_QUERY_REWRITE

See Also:

Using XQuery with Oracle XML DB 5-35

Performance Tuning for XQuery

Improving Performance for fn:doc and fn:collection on Repository Data
In Oracle XML DB, you can use XQuery functions fn:doc and fn:collection to
reference documents and collections in Oracle XML DB Repository. When repository
XML data is stored object-relationally or as binary XML, queries that use fn:doc and
fn:collection are evaluated functionally; that is, they are not optimized to access
the underlying storage tables directly.
To improve the performance of such queries, you must link them to the actual
database tables that hold the repository data being queried. You can do that in either of
the following ways:
■

■

Join view RESOURCE_VIEW with the XMLType table that holds the data, and then
use the Oracle SQL functions equals_path and under_path instead of the
XQuery functions fn:doc and fn:collection, respectively. These SQL
functions reference repository resources in a performant way.
Use the Oracle XQuery extension-expression pragma ora:defaultTable.

Both methods have the same effect. Oracle recommends that you use the
ora:defaultTable pragma because it lets you continue to use the XQuery standard
functions fn:doc and fn:collection and it simplifies your code.
These two methods are illustrated in the examples of this section.

Using equals_path and under_path Instead of fn:doc and fn:collection
SQL function equals_path references a resource located at a specified repository
path, and SQL function under_path references a resource located under a specified
repository path. Example 5–19 and Example 5–20 illustrate this for functions fn:doc
and equals_path; functions fn:collection and under_path are treated
similarly.
Example 5–19

Unoptimized Repository Query using fn:doc

SELECT XMLQuery('let $val :=
fn:doc("/home/OE/PurchaseOrders/2002/Sep/VJONES-20021009123337583PDT.xml")
/PurchaseOrder/LineItems/LineItem[@ItemNumber =19]
return $val' RETURNING CONTENT)
FROM DUAL;
Example 5–20

Optimized Repository Query using EQUALS_PATH

SELECT XMLQuery('let $val := $DOC/PurchaseOrder/LineItems/LineItem[@ItemNumber = 19]
return $val' PASSING OBJECT_VALUE AS "DOC" RETURNING CONTENT)
FROM RESOURCE_VIEW rv, purchaseorder p
WHERE ref(p) = XMLCast(XMLQuery('declare default element namespace
"http://xmlns.oracle.com/xdb/XDBResource.xsd"; (: :)
fn:data6(/Resource/XMLRef)' PASSING rv.RES RETURNING CONTENT)
AS REF XMLType)
AND equals_path(rv.RES, '/home/OE/PurchaseOrders/2002/Sep/VJONES-20021009123337583PDT.xml')
= 1;

Using Oracle XQuery Pragma ora:defaultTable
Oracle XQuery extension-expression pragma ora:defaultTable lets you specify
the default table used to store repository data that you query. The query is rewritten to
automatically join the default table to view RESOURCE_VIEW and use Oracle SQL
6

XQuery function fn:data is used here to atomize its argument, in this case returning the
XMLRef node's typed atomic value.

5-36 Oracle XML DB Developer's Guide

XQuery Static Type-Checking in Oracle XML DB

functions equals_path and under_path instead of XQuery functions fn:doc and
fn:collection, respectively. The effect is thus the same as coding the query
manually to use an explicit join and equals_path or under_path. Example 5–21
illustrates this; the query is rewritten automatically to what is shown in Example 5–20.
Example 5–21

Repository Query using Oracle XQuery Pragma ora:defaultTable

SELECT XMLQuery('for $doc in (#ora:defaultTable PURCHASEORDER #)
{fn:doc("/home/OE/PurchaseOrders/2002/Sep/VJONES-20021009123337583PDT.xml")}
let $val := $doc/PurchaseOrder/LineItems/LineItem[@ItemNumber = 19]
return $val}'
RETURNING CONTENT)
FROM DUAL;

For clarity of scope Oracle recommends that you apply pragma ora:defaultTable
directly to the relevant document or collection expression, fn:doc or
fn:collection, rather than to a larger expression.

XQuery Static Type-Checking in Oracle XML DB
Oracle XML DB type-checks all XQuery expressions. Doing this at run time can be
costly, however. As an optimization technique, whenever there is sufficient static type
information available for a given query at compile time, Oracle XML DB performs
static (compile time) type-checking of that query. Whenever sufficient static type
information is not available for a given query at compile time, Oracle XML DB uses
dynamic (run-time) type checking for that query.
Static type-checking can save execution time by raising errors at compile time. Static
type-checking errors include both data-type errors and the use of XPath expressions
that are invalid with respect to an XML schema.
Typical ways of providing sufficient static type information at query compile time
include the following:
■
■

Using XQuery with fn:doc or fn:collection over relational data.
Using XQuery to query an XMLType table, column, or view whose XML Schema
information is available at query compile time.

This section presents examples that demonstrate the utility of static type-checking and
the use of these two means of communicating type information.
The XML data produced on the fly by fn:collection together with URI scheme
oradb has ROW as its top-level element, but the query of Example 5–22 incorrectly
lacks that ROW wrapper element. This omission raises a query compile-time error.
Forgetting that fn:collection with oradb wraps relational data in this way is an
easy mistake to make, and one that could be difficult to diagnose without static
type-checking. Example 5–5 shows the correct code.
Example 5–22

Static Type-Checking of XQuery Expressions: oradb URI scheme

-- This produces a static-type-check error, because "ROW" is missing.
SELECT XMLQuery('for $i in fn:collection("oradb:/HR/REGIONS"),
$j in fn:collection("oradb:/HR/COUNTRIES")
where $i/REGION_ID = $j/REGION_ID and $i/REGION_NAME = "Asia"
return $j'
RETURNING CONTENT) AS asian_countries
FROM DUAL;
SELECT XMLQuery('for $i in fn:collection("oradb:/HR/REGIONS"),
*
ERROR at line 1:
ORA-19276: XPST0005 - XPath step specifies an invalid element/attribute name:
Using XQuery with Oracle XML DB 5-37

SQL*Plus XQUERY Command

(REGION_ID)

In Example 5–23, XQuery static type-checking finds a mismatch between an XPath
expression and its target XML schema-based data. Element CostCenter is misspelled
here as costcenter (XQuery and XPath are case-sensitive). Example 5–11 shows the
correct code.
Example 5–23

Static Type-Checking of XQuery Expressions: Schema-Based XML

-- This results in a static-type-check error: CostCenter is not the right case.
SELECT xtab.poref, xtab.usr, xtab.requestor
FROM purchaseorder,
XMLTable('for $i in /PurchaseOrder where $i/costcenter eq "A10" return $i'
PASSING OBJECT_VALUE
COLUMNS poref
VARCHAR2(20) PATH 'Reference',
usr
VARCHAR2(20) PATH 'User' DEFAULT 'Unknown',
requestor VARCHAR2(20) PATH 'Requestor') xtab;
FROM purchaseorder,
*
ERROR at line 2:
ORA-19276: XPST0005 - XPath step specifies an invalid element/attribute name:
(costcenter)

SQL*Plus XQUERY Command
Example 5–24 shows how you can enter an XQuery expression directly at the
SQL*Plus command line, by preceding the expression with the SQL*Plus command
XQUERY and following it with a slash (/) on a line by itself. Oracle Database treats
XQuery expressions submitted with this command the same way it treats XQuery
expressions in SQL/XML functions XMLQuery and XMLTable. Execution is identical,
with the same optimizations.
Example 5–24
SQL>
2
3
4

Using the SQL*Plus XQUERY Command

XQUERY for $i in fn:collection("oradb:/HR/DEPARTMENTS")
where $i/ROW/DEPARTMENT_ID < 50
return $i
/

Result Sequence
-------------------------------------------------------------------------------10Administration2001700
20Marketing2011800
30Purchasing1141700
40Human Resources2032400

There are also a few SQL*Plus SET commands that you can use for settings that are
specific to XQuery. Use SHOW XQUERY to see the current settings.
■

SET XQUERY BASEURI – Set the base URI for XQUERY. URIs in XQuery
expressions are relative to this URI.

5-38 Oracle XML DB Developer's Guide

Using XQuery with PL/SQL, JDBC, and ODP.NET

■

SET XQUERY CONTEXT – Specify a context item for subsequent XQUERY
evaluations.
See Also:

SQL*Plus User's Guide and Reference

Using XQuery with PL/SQL, JDBC, and ODP.NET
Previous sections in this chapter have shown how to invoke XQuery from SQL. This
section provides examples of using XQuery with the Oracle APIs for PL/SQL, JDBC,
and Oracle Data Provider for .NET (ODP.NET).
Example 5–25 shows how to use XQuery with PL/SQL, in particular, how to bind
dynamic variables to an XQuery expression using the XMLQuery PASSING clause. The
bind variables :1 and :2 are bound to the PL/SQL bind arguments nbitems and
partid, respectively. These are then passed to XQuery as XQuery variables itemno
and id, respectively.
Example 5–25

Using XQuery with PL/SQL

DECLARE
sql_stmt VARCHAR2(2000); -- Dynamic SQL statement to execute
nbitems NUMBER := 3; -- Number of items
partid
VARCHAR2(20):= '715515009058'; -- Part ID
result
XMLType;
doc
DBMS_XMLDOM.DOMDocument;
ndoc
DBMS_XMLDOM.DOMNode;
buf
VARCHAR2(20000);
BEGIN
sql_stmt :=
'SELECT XMLQuery(
''for $i in fn:collection("oradb:/OE/PURCHASEORDER") ' ||
'where count($i/PurchaseOrder/LineItems/LineItem) = $itemno ' ||
'and $i/PurchaseOrder/LineItems/LineItem/Part/@Id = $id ' ||
'return $i/PurchaseOrder/LineItems'' ' ||
'PASSING :1 AS "itemno", :2 AS "id" ' ||
'RETURNING CONTENT) FROM DUAL';
EXECUTE IMMEDIATE sql_stmt INTO result USING nbitems, partid;
doc := DBMS_XMLDOM.newDOMDocument(result);
ndoc := DBMS_XMLDOM.makeNode(doc);
DBMS_XMLDOM.writeToBuffer(ndoc, buf);
DBMS_OUTPUT.put_line(buf);
END;
/

This produces the following output:


Samurai 2: Duel at Ichijoji Temple



The Red Shoes



A Night to Remember



Using XQuery with Oracle XML DB 5-39

Using XQuery with PL/SQL, JDBC, and ODP.NET




A Night to Remember



The Unbearable Lightness Of Being



Sisters



PL/SQL procedure successfully completed.

Example 5–26 shows how to use XQuery with JDBC, binding variables by position
with the PASSING clause of SQL/XML function XMLTable.
Example 5–26
import
import
import
import
import

Using XQuery with JDBC

java.sql.*;
oracle.sql.*;
oracle.jdbc.*;
oracle.xdb.XMLType;
java.util.*;

public class QueryBindByPos
{
public static void main(String[] args) throws Exception, SQLException
{
System.out.println("*** JDBC Access of XQuery using Bind Variables ***");
DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
OracleConnection conn
= (OracleConnection)
DriverManager.getConnection("jdbc:oracle:oci8:@localhost:1521:ora11gR1", "oe", "oe");
String xqString
= "SELECT COLUMN_VALUE" +
"FROM XMLTable('for $i in fn:collection(\"oradb:/OE/PURCHASEORDER\") " +
"where $i/PurchaseOrder/Reference= $ref " +
"return $i/PurchaseOrder/LineItems' " +
"PASSING ? AS \"ref\")";
OraclePreparedStatement stmt = (OraclePreparedStatement)conn.prepareStatement(xqString);
String refString = "EABEL-20021009123336251PDT"; // Set the filter value
stmt.setString(1, refString); // Bind the string
ResultSet rs = stmt.executeQuery();
while (rs.next())
{
XMLType desc = (XMLType) rs.getObject(1);
System.out.println("LineItem Description: " + desc.getStringVal());
desc.close();
}
rs.close();
stmt.close();
}
}

This produces the following output:
*** JDBC Access of Database XQuery with Bind Variables ***
5-40 Oracle XML DB Developer's Guide

Using XQuery with PL/SQL, JDBC, and ODP.NET

LineItem Description: Samurai 2: Duel at Ichijoji Temple
LineItem Description: The Red Shoes
LineItem Description: A Night to Remember

Example 5–27 shows how to use XQuery with ODP.NET and the C# language. The C#
input parameters :nbitems and :partid are passed to XQuery as XQuery variables
itemno and id, respectively.
Example 5–27
using
using
using
using
using
using
using

Using XQuery with ODP.NET and C#

System;
System.Data;
System.Text;
System.IO;
System.Xml;
Oracle.DataAccess.Client;
Oracle.DataAccess.Types;

namespace XQuery
{
/// 

/// Demonstrates how to bind variables for XQuery calls
/// 
class XQuery
{
/// 

/// The main entry point for the application.
/// 
static void Main(string[] args)
{
int rows = 0;
StreamReader sr = null;
// Create the connection.
string constr = "User Id=oe;Password=***********;Data Source=ora11gr2"; // Replace with real password.
OracleConnection con = new OracleConnection(constr);
con.Open();
// Create the command.
OracleCommand cmd = new OracleCommand("", con);
// Set the XML command type to query.
cmd.CommandType
= CommandType.Text;
// Create the SQL query with the XQuery expression.
StringBuilder blr = new StringBuilder();
blr.Append("SELECT COLUMN_VALUE FROM XMLTable");
blr.Append("(\'for $i in fn:collection(\"oradb:/OE/PURCHASEORDER\") ");
blr.Append("
where count($i/PurchaseOrder/LineItems/LineItem) = $itemno ");
blr.Append("
and $i/PurchaseOrder/LineItems/LineItem/Part/@Id = $id ");
blr.Append("
return $i/PurchaseOrder/LineItems\' ");
blr.Append(" PASSING :nbitems AS \"itemno\", :partid AS \"id\")");
cmd.CommandText = blr.ToString();
cmd.Parameters.Add(":nbitems", OracleDbType.Int16, 3, ParameterDirection.Input);
cmd.Parameters.Add(":partid", OracleDbType.Varchar2, "715515009058", ParameterDirection.Input);
// Get the XML document as an XmlReader.
OracleDataReader dr = cmd.ExecuteReader();
dr.Read();
// Get the XMLType column as an OracleXmlType
OracleXmlType xml = dr.GetOracleXmlType(0);
// Print the XML data in the OracleXmlType object

Using XQuery with Oracle XML DB 5-41

Oracle XML DB Support for XQuery

Console.WriteLine(xml.Value);
xml.Dispose();
// Clean up.
cmd.Dispose();
con.Close();
con.Dispose();
}
}
}

This produces the following output:


Samurai 2: Duel at Ichijoji Temple



The Red Shoes



A Night to Remember




See Also:
■

Chapter 13, "PL/SQL APIs for XMLType"

■

Chapter 15, "Java DOM API for XMLType"

■

Chapter 17, "Using Oracle Data Provider for .NET with Oracle
XML DB"

Oracle XML DB Support for XQuery
This section describes Oracle XML DB for the XQuery language.

Support for XQuery and SQL
Support for the XQuery language in Oracle XML DB is designed to provide the best fit
between the worlds of relational storage and querying XML data. That is, Oracle
XML DB is a general XQuery implementation, but it is in addition specifically
designed to make relational and XQuery queries work well together.
The specific properties of the Oracle XML DB XQuery implementation are described in
this section. The XQuery standard explicitly calls out certain aspects of the language
processing as implementation-defined or implementation-dependent. There are also
some features that are specified by the XQuery standard but are not supported by
Oracle XML DB.

Implementation Choices Specified in the XQuery Standard
The XQuery specification specifies that each of the following aspects of language
processing is to be defined by the implementation.
■

Implicit time zone support – In Oracle XML DB, the implicit time zone is always
assumed to be Z, and instances of xs:date, xs:time, and xs:datetime that are
missing time zones are automatically converted to UTC.

5-42 Oracle XML DB Developer's Guide

Oracle XML DB Support for XQuery

XQuery Features Not Supported by Oracle XML DB
The following features specified by the XQuery standard are not supported by Oracle
XML DB:
■

■

■

Copy-namespace mode – Oracle XML DB supports only preserve and inherit for
a copy-namespaces declaration. If an existing element node is copied by an
element constructor or a document constructor, all in-scope namespaces of the
original element are retained in the copy. Otherwise, the copied node inherits all
in-scope namespaces of the constructed node. An error is raised if you specify
no-preserve or no-inherit.
Version encoding – Oracle XML DB does not support an optional encoding
declaration in a version declaration. That is, you cannot include (encoding
an-encoding) in a declaration xquery version a-version;. In particular,
you cannot specify an encoding used in the query. An error is raised if you include
an encoding declaration.
xml:id – Oracle XML DB does not support use of xml:id. If you use xml:id, then
an error is raised.

■

XQuery prolog default-collation declaration.

■

XQuery prolog boundary-space declaration.

■

XQuery data type xs:duration. Use either xs:yearMonthDuration or
xs:DayTimeDuration instead.

XQuery Optional Features
The following optional features specified by the XQuery standard are not supported
by Oracle XML DB:
■

Schema Validation Feature

■

Module Feature

Support for XQuery Functions and Operators
Oracle XML DB supports all of the XQuery functions and operators included in the
latest XQuery 1.0 and XPath 2.0 Functions and Operators specification, with the following
exceptions. There is no support for the following:
■

The XQuery regular-expression functions: fn:matches, fn:replace, and
fn:tokenize. Use Oracle XQuery functions ora:matches, ora:replace, and
ora:tokenize instead, respectively.

■

Functions fn:id and fn:idref.

■

Function fn:collection without arguments.

■

Optional collation parameters for XQuery functions.

XQuery Functions fn:doc, fn:collection, and fn:doc-available
Oracle XML DB supports XQuery functions fn:doc, fn:collection, and
fn:doc-available for all resources in Oracle XML DB Repository.
Function fn:doc returns the repository file resource that is targeted by its URI
argument; it must be a file of well-formed XML data. Function fn:collection is
similar, but works on repository folder resources (each file in the folder must contain
well-formed XML data).

Using XQuery with Oracle XML DB 5-43

Oracle XML DB Support for XQuery

When used with Oracle URI scheme oradb, fn:collection can return XML data
derived on the fly from existing relational data that is not in the repository.
XQuery function fn:collection raises an error when used with URI scheme
oradb, if its targeted table or view, or a targeted column, does not exist. Functions
fn:doc and fn:collection do not raise an error if the repository resource passed
as argument is not found. Instead, they return an empty sequence.
You can determine whether a given document exists using XQuery function
fn:doc-available. It returns true if its document argument exists, false if not.
See Also: http://www.w3.org for the definitions of XQuery
functions and operators

5-44 Oracle XML DB Developer's Guide

6
Indexing XMLType Data
You can create indexes on your XML data, to focus on particular parts of it that you
query often and thus improve performance. This chapter includes guidelines for doing
this. It describes various ways that you can index XMLType data, whether
schema-based or non-schema-based, and regardless of the XMLType storage model
you use (binary XML, unstructured, hybrid, or structured).
This chapter contains these topics:
■

Oracle XML DB Tasks Involving Indexes

■

Overview of Indexing XMLType Data

■

Indexing XMLType Data Stored Object-Relationally

■

XMLIndex

■

Oracle Text Indexes on XML Data

The execution plans shown here are for illustration only. If you
run the examples presented here in your environment then your
execution plans might not be identical.

Note:

See Also:
■
■

Oracle Database Concepts for an overview of indexing
Oracle Database Advanced Application Developer's Guide for
information about using indexes in application development

Oracle XML DB Tasks Involving Indexes
Table 6–1 identifies the documentation for some basic user tasks involving indexes for
XML data.

Indexing XMLType Data

6-1

Oracle XML DB Tasks Involving Indexes

Table 6–1

Basic XML Indexing Tasks

For information about how to...

See...

Index XMLType data stored object-relationally

"Indexing XMLType Data Stored
Object-Relationally" on page 6-6,
"Guideline: Create indexes on ordered
collection tables" on page 8-6

Create, drop, or rename an XMLIndex index

Example 6–6 on page 6-18, Example 6–8 on
page 6-18

Obtain the name of an XMLIndex index for a given table or column

Example 6–7 on page 6-18

Determine whether a given XMLIndex index is used in evaluating a
query

"How to Tell Whether XMLIndex is Used"
on page 6-25

Turn off use of an XMLIndex index

"Turning Off Use of XMLIndex" on
page 6-30

Table 6–2 identifies the documentation for some user tasks involving XMLIndex
indexes that have a structured component.
Table 6–2

Tasks Involving XMLIndex Indexes with a Structured Component

For information about how to...

See...

Create an XMLIndex index with a structured component

Example 6–20 on page 6-23, Example 6–24
on page 6-24

Drop the structured component of an XMLIndex index (drop all
structure groups)

Example 6–21 on page 6-24

Ensure data type correspondence between a query and an XMLIndex "Data Type Considerations for XMLIndex
index with a structured component
Structured Component" on page 6-11
Create a B-tree index on a content table of an XMLIndex structured
component

Example 6–22 on page 6-24

Create an Oracle Text CONTEXT index on a content table of an
XMLIndex structured component

Example 6–23 on page 6-24

Table 6–3 identifies the documentation for some user tasks involving XMLIndex
indexes that have an unstructured component.
Table 6–3

Tasks Involving XMLIndex Indexes with an Unstructured Component

For information about how to...

See...

Create an XMLIndex index with an unstructured component

Example 6–9 on page 6-19, Example 6–11
on page 6-20, Example 6–31 on page 6-31,
Example 6–33 on page 6-32, Example 6–34
on page 6-34, Example 6–35 on page 6-35,
Example 6–36 on page 6-36

Drop the unstructured component of an XMLIndex index (drop the
path table)

Example 6–12 on page 6-20

Name the path table when creating an XMLIndex index

Example 6–9 on page 6-19

Specify storage options when creating an XMLIndex index

Example 6–11 on page 6-20

Show all existing secondary indexes on an XMLIndex path table

Example 6–13 on page 6-20, Example 6–19
on page 6-22

Obtain the name of a path table for an XMLIndex index

Example 6–10 on page 6-19

Obtain the name of an XMLIndex index with an unstructured
component, given its path table

Example 6–26 on page 6-27

6-2 Oracle XML DB Developer's Guide

Overview of Indexing XMLType Data

Table 6–3 (Cont.) Tasks Involving XMLIndex Indexes with an Unstructured Component
For information about how to...

See...

Create a secondary index on an XMLIndex path table

"Using XMLIndex with an Unstructured
Component" on page 6-19

Obtain information about all of the secondary indexes on an
XMLIndex path table

Example 6–19 on page 6-22

Create a function-based index on a path-table VALUE column

Example 6–14 on page 6-21

Create a numeric index on a path-table VALUE column

Example 6–16 on page 6-21

Create a date index on a path-table VALUE column

Example 6–17 on page 6-21

Create an Oracle Text CONTEXT index on a path-table VALUE column

Example 6–18 on page 6-22

Exclude or include particular XPath expressions from use by an
XMLIndex index

"XMLIndex Path Subsetting: Specifying the
Paths You Want to Index" on page 6-30

Specify namespace prefixes for XPath expressions used for
XMLIndex

"XMLIndex Path Subsetting: Specifying the
Paths You Want to Index" on page 6-30

Exclude or include particular XPath expressions from use by an
XMLIndex index

"XMLIndex Path Subsetting: Specifying the
Paths You Want to Index" on page 6-30

Specify namespace prefixes for XPath expressions used for
XMLIndex

"XMLIndex Path Subsetting: Specifying the
Paths You Want to Index" on page 6-30

Table 6–4 identifies the documentation for some other user tasks involving XMLIndex
indexes.
Table 6–4

Miscellaneous Tasks Involving XMLIndex Indexes

For information about how to...

See...

Specify that an XMLIndex index should be created and maintained
using parallel processes

"XMLIndex Partitioning and Parallelism"
on page 6-34

Change the parallelism of an XMLIndex path table to tune index
performance

"XMLIndex Partitioning and Parallelism"
on page 6-34

Schedule maintenance for an XMLIndex index

"Asynchronous (Deferred) Maintenance of
XMLIndex Indexes" on page 6-35

Manually synchronize an XMLIndex index and its base table

"Asynchronous (Deferred) Maintenance of
XMLIndex Indexes" on page 6-35

Collect statistics on a table or index for the cost-based optimizer

Example 6–38 on page 6-37

Create an Oracle Text CONTEXT index

Example 6–39 on page 6-46

Create an Oracle Text CONTEXT index on a content table of an
XMLIndex structured component

Example 6–23 on page 6-24

Use an Oracle Text CONTEXT index for full-text search of XML data

Example 6–40 on page 6-46

Show whether an Oracle Text CONTEXT index is used in a query

Example 6–40 on page 6-46

Overview of Indexing XMLType Data
Database indexes improve performance by providing faster access to table data. The
use of indexes is particularly recommended for online transaction processing (OLTP)
environments involving few updates.
The principle way you index XML data is using XMLIndex. You can also use Oracle
Text CONTEXT indexes to supplement the use of XMLIndex.

Indexing XMLType Data

6-3

Overview of Indexing XMLType Data

XMLIndex Addresses the Fine-Grained Structure of XML Data
You can create indexes on one or more table columns, or on a functional expression.
XML data, however, has its own, fine-grained structure, which is not necessarily
reflected in the structure of the database tables used to store it. For this reason,
effectively indexing XML data can be a bit different from indexing most database data.
For structured XML storage, XML objects such as elements and attributes correspond
to object-relational columns and tables, so creating B-tree indexes on those columns and
tables provides an excellent way to effectively index the corresponding XML objects.
Here, the storage model directly reflects the fine-grained structure of the XML data, so
there is no special problem for indexing structured XML data. See "Indexing XMLType
Data Stored Object-Relationally" on page 6-6.
For unstructured, hybrid, and binary XML storage models, indexing a database
column using the standard sorts of index (B-tree, bitmap) is generally not helpful for
accessing particular parts of an XML document. If an XMLType column that contains
an XML document is stored as a CLOB instance, then the details within that document
are inaccessible to the column index—the entire document acts as a single unit as far
as the column index is concerned. In hybrid storage, part of an XML document is
broken up and stored object-relationally (structured storage), but one or more XML
fragments are stored as CLOB instances (unstructured storage). A typical use case here
is mapping an XML-schema complexType or a complex element to CLOB storage,
because the entire fragment is generally accessed as a unit. For standard indexes, it
acts as a unit for indexing as well.
XMLIndex provides a general, XML-specific index that indexes the internal structure
of XML data. One of its main purposes is to overcome the indexing limitation
presented by unstructured, hybrid, and binary XML storage.
■

■

An XMLIndex index with an unstructured component indexes the XML tags of your
document and identifies document fragments based on XPath expressions that
target them. It can also index scalar node values, to provide quick lookup based on
individual values or ranges of values. It also records document hierarchy
information for each node it indexes: relations parent–child, ancestor–descendant,
and sibling. This index component is particularly useful for queries that extract
XML fragments from documents that have little or variable structure.
An XMLIndex index with a structured component indexes highly structured and
predictable parts of XML data that is nevertheless for the most part unstructured.
This index component is particularly useful for queries that project and use such
islands of structured content.
See Also:

"XMLIndex" on page 6-7

Oracle Text Indexes
Besides accessing XML nodes such as elements and attributes, it is sometimes
important to provide fast access to particular passages of text within XML text nodes.
This is the purpose of Oracle Text indexes: they index full-text strings. An Oracle Text
CONTEXT index enables Oracle SQL function contains for full-text search over XML.
With structured storage, XPath rewrite can often rewrite queries that use XPath
function ora:contains to queries that use SQL function contains, so in those cases
too an Oracle Text index can be employed.
Full-text indexing is particularly useful for document-centric applications, which often
contain a mix of XML elements and text-node content. Full-text searching can often be
made more powerful, more focused, by combining it with structural XML searching,

6-4 Oracle XML DB Developer's Guide

Overview of Indexing XMLType Data

that is, by restricting it to certain parts of an XML document, which are identified by
using XPath expressions.
See Also:

"Oracle Text Indexes on XML Data" on page 6-46

Optimization Chooses the Right Indexes to Use
Which indexes are used when more than one might apply in a given case? Cost-based
optimization determines the index or indexes to use, so that performance is
maximized. Oracle Text indexes apply only to text, which, for XML data, means text
nodes. Whenever text nodes are targeted and a corresponding Oracle Text index is
defined, it is used. If other indexes are also appropriate in a particular context, then
they can be used as well. However, just because an index is defined and it might
appear applicable in a given situation does not mean that it will be used—it will not
be used if the cost-based optimizer deems that its use is not cost-effective.

Deprecated Indexes for XML Data
In releases prior to Oracle Database 11g Release 1 (11.1), CTXXPath indexes were
sometimes appropriate for use with XMLType data. In releases prior to Oracle
Database 11g Release 2 (11.2), function-based indexes were sometimes appropriate for
use with XMLType data. These indexing methods are no longer recommended for use
with XMLType data.

Function-Based Indexes
In releases prior to Oracle Database 11g Release 2 (11.2), function-based indexes were
sometimes appropriate for use with XMLType data when an XPath expression targeted
a singleton node. Oracle recommends that you use the structured component of
XMLIndex instead. Doing so obviates the overhead associated with maintenance
operations on function-based indexes, and it increases the number of situations in
which the optimizer can correctly select the index. No changes to existing DML
statements are required as a result of this.
It continues to be the case that, for structured storage, defining an index for
(deprecated) Oracle SQL function extractValue often leads, by XPath rewrite, to
automatic creation of B-tree indexes on the underlying objects (instead of a
function-based index on extractValue). The XPath target here must be a singleton
element or attribute. A similar shortcut exists for XMLCast applied to XMLQuery.
See Also:
■

"Indexing XMLType Data Stored Object-Relationally" on page 6-6

■

"XMLIndex Structured Component" on page 6-10

CTXXPath Indexes
Another type of index that is available for indexing XML data, CTXXPath, is
deprecated, starting with Oracle Database 11g Release 1 (11.1). It has been superseded
by XMLIndex, and it is made available only for use with older database releases. It cannot
help in extracting an XML fragment, and it acts only as a preliminary filter for equality
predicates; after such filtering, XPath expressions are evaluated functionally (that is,
without the benefit of XPath rewrite).

Indexing XMLType Data

6-5

Indexing XMLType Data Stored Object-Relationally

Note: CTXSYS.CTXXPath indexing was deprecated in Oracle
Database 11g Release 1 (11.1). The functionality that was provided by
CTXXPath is now provided by XMLIndex.

Oracle recommends that you replace CTXXPath indexes with
XMLIndex indexes. The intention is that CTXXPath will no longer be
supported in a future release of the database.

Indexing XMLType Data Stored Object-Relationally
You can effectively index XML data that is stored object-relationally (structured
storage) by creating B-tree indexes on the underlying database columns that
correspond to XML nodes.
If the data to be indexed is a singleton, that is, if it can occur only once in any XML
instance document, then you can use a shortcut of ostensibly creating a function-based
index, where the expression defining the index is a functional application, with an
XPath-expression argument that targets the singleton data. A shortcut is defined for
XMLCast applied to XMLQuery, and another shortcut is defined for (deprecated)
Oracle SQL function extractValue.
In many cases, Oracle XML DB then automatically creates appropriate indexes on the
underlying object-relational tables or columns; it does not create a function-based
index on the targeted XMLType data as the CREATE INDEX statement would suggest.
In the case of the extractValue shortcut, the index created is a B-tree index. In the
case of XMLCast applied to XMLQuery, the index created is a function-based index on
the scalar value resulting from the functional expression. "Indexing Non-Repeating
text() Nodes or Attribute Values" describes this.
If the data to be indexed is a collection, then you cannot use such a shortcut; you must
create the B-tree indexes manually. "Indexing Repeating (Collection) Elements" on
page 6-7 describes this.

Indexing Non-Repeating text() Nodes or Attribute Values
Table purchaseorder in sample database schema OE is stored object-relationally.
Each purchase-order document has a single Reference element; this element is a
singleton. You can thus use a shortcut to create an index on the underlying
object-relational data.
Example 6–1 shows a CREATE INDEX statement that ostensibly tries to create a
function-based index using XMLCast applied to XMLQuery, targeting the text content
of element Reference. (The content of this element is only text, so targeting the
element is the same as targeting its text node using node test text().)
Example 6–2 ostensibly tries to create a function-based index using (deprecated)
Oracle SQL function extractValue, targeting the same data.
Example 6–1 CREATE INDEX using XMLCAST and XMLQUERY on a Singleton Element
CREATE INDEX po_reference_ix ON purchaseorder
(XMLCast(XMLQuery ('$p/PurchaseOrder/Reference' PASSING po.OBJECT_VALUE AS "p"
RETURNING CONTENT)
AS VARCHAR2(128)));
Example 6–2 CREATE INDEX using EXTRACTVALUE on a Singleton Element
CREATE INDEX po_reference_ix ON purchaseorder
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(extractValue(OBJECT_VALUE, '/PurchaseOrder/Reference'));

In reality, in both Example 6–1 and Example 6–2 no function-based index is created on
the targeted XMLType data. Instead, Oracle XML DB rewrites the CREATE INDEX
statements to create indexes on the underlying scalar data.
See Also: Example 8–4 and Example 8–5 on page 8-5 for information
about XPath rewrite as it applies to such CREATE INDEX statements

In some cases when you use either of these shortcuts, the CREATE INDEX statement is
not able to create an index on the underlying scalar data as described, and it instead
actually does create a function-based index on the referenced XMLType data. (This is
so, even if the value of the index might be a scalar.)
If this happens, drop the index, and create instead an XMLIndex index with a
structured component that targets the same XPath. As a general rule, Oracle
recommends against using a function-based index on XMLType data.
This is an instance of a general rule for XMLType data, regardless of the storage
method used: Use an XMLIndex with a structured component instead of a
function-based index. This rule applies starting with Oracle Database 11g Release 2
(11.2). Respecting this rule obviates the overhead associated with maintenance
operations on function-based indexes, and it can increase the number of situations in
which the optimizer can correctly select the index.
See Also:

"Function-Based Indexes" on page 6-5

Indexing Repeating (Collection) Elements
In structured storage, a collection is stored as an ordered collection table (OCT) of an
XMLType instance, which means that you can directly access its members. Because the
structured storage model directly reflects the fine-grained structure of the XML data,
you can create indexes that target individual collection members.
You must create such indexes manually. The special feature of automatically creating
B-tree indexes when you ostensibly create a function-based index for (deprecated)
Oracle SQL function extractValue does not apply to collections (the XPath
expression passed to extractValue must target a singleton).
To create B-tree indexes for a collection, you must understand the structure of the SQL
object that is used to manage the collection. Given this information, you can use
conventional object-relational SQL code to created the indexes directly on the
appropriate SQL-object attributes. Refer to "Guideline: Create indexes on ordered
collection tables" on page 8-6 for an example of how to do this.

XMLIndex
This section contains these topics:
■

Advantages of XMLIndex

■

Structured and Unstructured XMLIndex Components

■

XMLIndex Structured Component

■

XMLIndex Unstructured Component

■

Creating, Dropping, Altering, and Examining an XMLIndex Index

■

Using XMLIndex with an Unstructured Component

Indexing XMLType Data

6-7

XMLIndex

■

Using XMLIndex with a Structured Component

■

How to Tell Whether XMLIndex is Used

■

Turning Off Use of XMLIndex

■

XMLIndex Path Subsetting: Specifying the Paths You Want to Index

■

Guidelines for Using XMLIndex with an Unstructured Component

■

Guidelines for Using XMLIndex with a Structured Component

■

XMLIndex Partitioning and Parallelism

■

Asynchronous (Deferred) Maintenance of XMLIndex Indexes

■

Collecting Statistics on XMLIndex Objects for the Cost-Based Optimizer

■

Data Dictionary Static Public Views Related to XMLIndex

■

PARAMETERS Clause for CREATE INDEX and ALTER INDEX

B-tree indexes can be used advantageously with structured (object-relational)
storage—they provide sharp focus by targeting the underlying objects directly. They
are generally ineffective, however, in addressing the detailed structure (elements and
attributes) of an XML document stored using binary XML or CLOB storage, or of an
XML fragment stored in a CLOB instance embedded in object-relational storage. That is
the special domain of XMLIndex: unstructured and hybrid storage.
One typical use case for XMLIndex is where you generally expect to access certain
portions of a document in their entirety, so you pack those portions into one or more
CLOB instances. You might nevertheless sometimes need to query within these
document portions. XMLIndex can help here.
Another use case is where an XML schema contains xsd:any elements, for lack of any
specific knowledge of the document structure and data types involved. The data
corresponding to these elements is stored in CLOB instances, and XMLIndex can be
used to speed access to it.

Advantages of XMLIndex
XMLIndex is a domain index; it is designed specifically for the domain of XML data. It
is a logical index. An XMLIndex index can be used for SQL/XML functions XMLQuery,
XMLTable, XMLExists, and XMLCast.
XMLIndex presents the following advantages over other indexing methods:
■

■

■

An XMLIndex index is effective in any part of a query; it is not limited to use in a
WHERE clause. This is not the case for any of the other kinds of indexes you might
use with XML data.
An XMLIndex index with an unstructured component can speed access to both
SELECT list data and FROM list data, making it useful for XML fragment extraction,
in particular. Function-based indexes and CTXXPath indexes, both of which are
deprecated, cannot be used to extract document fragments.
You can use an XMLIndex index with either XML schema-based or
non-schema-based data. You can use it with unstructured storage, hybrid storage,
and binary XML storage. B-tree indexing is appropriate only for XML
schema-based data that is stored object-relationally (structured storage); it is
ineffective for XML schema-based data stored in a CLOB instance.

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■

■

■

■

You can use an XMLIndex index for searches with XPath expressions that target
collections, that is, nodes that occur multiple times within a document. This is not
the case for function-based indexes.
You need no prior knowledge of the XPath expressions that might be used in
queries. The unstructured component of an XMLIndex index can be completely
general. This is not the case for function-based indexes.
If you have prior knowledge of the XPath expressions to be used in queries, then
you can improve performance either by using a structured XMLIndex component
that targets fixed, structured islands of data that are queried often.
XMLIndex indexing—both index creation and index maintenance—can be carried
out in parallel, using multiple database processes. This is not the case for
function-based and CTXXPATH indexes, which are deprecated.

Structured and Unstructured XMLIndex Components
XMLIndex is used to index XML data that is semi-structured1, that is, data that
generally has little or no fixed structure. It applies to data that is stored using binary
XML or CLOB-based storage. This includes XML data stored in CLOB instances that are
embedded in object-relational storage (hybrid storage).
Semi-structured XML data can sometimes nevertheless contain islands of predictable,
structured data. An XMLIndex index can therefore have two components: a structured
component, used to index such islands, and an unstructured component, used to
index data that has little or variable structure.
A structured component can help with queries that project and use islands of
structured content. An unstructured component can help with queries that extract
XML fragments. Either component can be omitted from a given XMLIndex index.
Unlike a structured component, an unstructured component is general and relatively
untargeted. Though you can restrict an unstructured component to apply only to
certain XPath subsets, its path table indexes node content that can be of different scalar
types, which can require you to create multiple secondary indexes on the VALUE
column to deal with the different data types—see "Secondary Indexes on Column
VALUE" on page 6-17. Using an unstructured component alone can also lead to
inefficiencies involving multiple probes and self-joins of its path table, for queries that
project structured islands.
On the other hand, a structured component is not suited for queries that involve little
structure or queries that extract XML fragments. Use a structured component to index
structured islands of data; use an unstructured component to index data that has little
structure.
Figure 6–1 is the same as Figure 1–5 in Chapter 1. The last row indicates the
applicability of XMLIndex for different XML data use cases. It shows that XMLIndex
is appropriate for semi-structured XML data, however it is stored (last three columns).
And an XMLIndex index with a structured component is useful for document-centric
data that contains structured islands (fourth column).

1

In this book, "structured" and "unstructured" generally refer to XMLType storage options; they
refer less often to the nature of your data. "Hybrid" refers to object-relational storage with
some embedded CLOB storage. "Semi-structured" refers to XML content, regardless of storage.
Unstructured storage is CLOB-based storage, and structured storage is object-relational
storage.

Indexing XMLType Data

6-9

XMLIndex

Figure 6–1 XML Use Cases and XML Indexing

Data-Centric

Document-Centric

Use Case

XML schema-based data,
with little variation and
little structural change
over time

XML schema-based
data, with some
embedded variable
data

Variable, free-form data,
with some fixed
embedded structures

Variable, free-form
data

Typical Data

Employee record

Employee record that
includes a free-form
resume

Technical article, with
author, date, and title
fields

Web document or
book chapter

Storage Model

Object-Relational
(Structured)

Hybrid

CLOB (Unstructured) or Binary XML

Indexing

B-tree index

·
·

XMLIndex index with
structured and
unstructured components

B-tree index
XMLIndex index with
unstructured component

XMLIndex index with
unstructured
component

See Also:
■

"XMLIndex Structured Component" on page 6-10

■

"XMLIndex Unstructured Component" on page 6-13

■

"Advantages of XMLIndex" on page 6-8 for a summary of the
advantages provided by each XMLIndex component type

XMLIndex Structured Component
You create and use the structured component of an XMLIndex index for queries that
project fixed, structured islands of XML content, even if the surrounding data is
relatively unstructured.
A structured XMLIndex component organizes such islands in a relational format. In
this it is similar to SQL/XML function XMLTable, and the syntax you use to define the
structured component reflects this similarity. The relational tables used to store the
indexing data are data-type aware, and each column can be of a different scalar data
type.
You can thus think of the act of creating the structured component of an XMLIndex
index as decomposing a structured portion of your XML data into relational format. This
differs from the object-relational storage model of XMLType in these ways:
■

■

■

■

A structured index component explicitly decomposes particular portions of your
data, which you specify—portions that you commonly query. Object-relational
XMLType storage involves automatic decomposition of an entire XMLType table or
column.
The structured component of an XMLIndex index applies to both XML
schema-based and non-schema-based data. Object-relational XMLType storage
applies only to data that is based on an XML schema.
The decomposed data for a structured XMLIndex component is stored in addition
to the XMLType data, as an index, rather than being the storage model for the
XMLType data itself.
For a structured XMLIndex component, the same data can be projected multiple
times, as columns of different data type.

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The index content tables used for the structured component of an XMLIndex index are
part of the index, but because they are normal relational tables you can, in turn, index
them using any standard relational indexes, including indexes that satisfy primary-key
and foreign-key constraints. You can also index them using domain indexes, such as
an Oracle Text CONTEXT index.
Another way to look at the structured component of an XMLIndex index sees that it
acts as a generalized function-based index. A function-based index is similar to a
structured XMLIndex component that has only one relational column.
If you find that for a particular application you are creating multiple function-based
indexes, then consider using a structured XMLIndex index instead. Create also B-tree
indexes on the columns of the structured index component.
Note:
■

■

Queries that use SQL/XML function XMLTable can typically be
rewritten to use the relational indexing tables of an XMLIndex
structured component. These tables also contain some internal,
system-defined columns. These internal columns might change in
the future, so do not write code that depends on any assumptions
about their existence or contents.
Queries that use Oracle SQL function XMLSequence within a SQL
TABLE collection expression, that is,
TABLE(XMLSequence(...)), are not rewritten to use the
indexing tables of an XMLIndex structured component. Oracle
SQL function XMLSequence is deprecated in Oracle Database 11g
Release 2; use standard SQL/XML function XMLTable instead.
See Oracle Database SQL Language Reference for information about
the SQL TABLE collection expression.

Ignore the Index Content Tables; They Are Transparent
Although the index content tables of an XMLIndex structured component are normal
relational tables, they are also read-only: you cannot add or drop their columns or
modify (insert, update, or delete) their rows.
You can thus generally ignore the relational index content tables. You cannot access
them, other than to DESCRIBE them and create (secondary) indexes on them. You
need never explicitly gather statistics on them. You need only collect statistics on the
XMLIndex index itself or the base table on which the XMLIndex index is defined;
statistics are collected and maintained on the index content tables transparently.
See Also: "Collecting Statistics on XMLIndex Objects for the
Cost-Based Optimizer" on page 6-37

Data Type Considerations for XMLIndex Structured Component
The relational tables that are used for an XMLIndex structured component use SQL
data types. XQuery expressions that are used in queries use XML data types (XML
Schema data types and XQuery data types).
XQuery typing rules can automatically change the data type of a subexpression, to
ensure coherence and type-checking. For example, if a document that is queried using
XPath expression /PurchaseOrder/LineItem[@ItemNumber = 25] is not XML
schema-based, then the subexpression @ItemNumber is untyped, and it is then
automatically cast to xs:double by the XQuery = comparison operator. To index this
Indexing XMLType Data

6-11

XMLIndex

data using an XMLIndex structured component you must use BINARY_DOUBLE as the
SQL data type.
This is a general rule. For an XMLIndex index with structured component to apply to a
query, the data types must correspond. Table 6–5 shows the data-type
correspondences.
Table 6–5

XML and SQL Data Type Correspondence for XMLIndex

XML Data Type

SQL Data Type

xs:decimal

INTEGER or NUMBER

xs:double

BINARY_DOUBLE

xs:float

BINARY_FLOAT

xs:date

DATE, TIMESTAMP WITH TIMEZONE

xs:dateTime

TIMESTAMP, TIMESTAMP WITH TIMEZONE

xs:dayTimeDuration

INTERVAL DAY TO SECOND

xs:yearMonthDuration

INTERVAL YEAR TO MONTH

If the XML data type is xs:date or xs:dateTime, and if you
know that the data that you will query and for which you are creating
an index will not contain a time-zone component, then you can
increase performance by using SQL data type DATE or TIMESTAMP. If
the data might contain a time-zone component, then you must use
SQL data type TIMESTAMP WITH TIMEZONE.
Note:

If the XML and SQL data types involved do not have a built-in one-to-one
correspondence, then you must make them correspond (according to Table 6–5), in
order for the index to be picked up for your query. There are two ways you can do this:
■

■

Make the index correspond to the query – Define (or redefine) the column in the
structured index component, so that it corresponds to the XML data type. For
example, if a query that you want to index uses the XML data type xs:double,
then define the index to use the corresponding SQL data type, BINARY_DOUBLE.
Make the query correspond to the index – In your query, explicitly cast the
relevant parts of an XQuery expression to data types that correspond to the SQL
data types used in the index content table.

Example 6–3 and Example 6–4 show how you can cast an XQuery expression in your
query to match the SQL data type used in the index content table.
Example 6–3 Making Query Data Compatible with Index Data – SQL Cast
SELECT count(*) FROM purchaseorder
WHERE XMLCast(XMLQuery('$p/PurchaseOrder/LineItem/@ItemNumber'
PASSING OBJECT_VALUE AS "p" RETURNING CONTENT)
AS INTEGER)
= 25;
Example 6–4 Making Query Data Compatible with Index Data – XQuery Cast
SELECT count(*) FROM purchaseorder
WHERE XMLExists('$p/PurchaseOrder/LineItem[xs:decimal(@ItemNumber) = 25]'
PASSING OBJECT_VALUE AS "p");

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Notice that the number 25 plays a different role in these two examples, even though in
both cases it is the purchase-order item number. In Example 6–3, 25 is a SQL number
of data type INTEGER; in Example 6–4, 25 is an XQuery number of data type
xs:decimal.
In Example 6–3, the XMLQuery result is cast to SQL type INTEGER, which is compared
with the SQL value 25. In Example 6–4, the value of attribute ItemNumber is cast (in
XQuery) to the XML data type xs:decimal, which is compared with the XQuery
value 25 and which corresponds to the SQL data type (INTEGER) used for the index.
There are thus two different kinds of data-type conversion in these examples, but they
both convert query data to make it type-compatible with the index content table.
See Also: "Mapping XML Schema Data Types to SQL Data Types"
on page 7-45 for information about the built-in correspondence
between XML Schema data types and SQL data types

XMLIndex Unstructured Component
Unlike a B-tree index, which you define for a specific database column that represents
an individual XML element or attribute, or the XMLIndex structured component,
which applies to specific, structured document parts, the unstructured component of
an XMLIndex index is, by default, very general. Unless you specify a more narrow
focus by detailing specific XPath expressions to use or not to use in indexing, an
unstructured XMLIndex component applies to all possible XPath expressions for your
XML data.
The unstructured component of an XMLIndex index has three logical parts:
■

■

■

A path index – This indexes the XML tags of a document and identifies its various
document fragments.
An order index – This indexes the hierarchical positions of the nodes in an XML
document. It keeps track of parent–child, ancestor–descendant, and sibling
relations.
A value index – This indexes the values of an XML document. It provides lookup
by either value equality or value range. A value index is used for values in query
predicates (WHERE clause).

The unstructured component of an XMLIndex index uses a path table and a set of
(local) secondary indexes on the path table, which implement the logical parts
described above. Two secondary indexes are created automatically:
■

A pikey index, which implements the logical indexes for both path and order.

■

A real value index, which implements the logical value index.

You can modify these two indexes or create additional secondary indexes. The path
table and its secondary indexes are all owned by the owner of the base table upon
which the XMLIndex index is created.
The pikey index handles paths and order relationships together, which gives the best
performance in most cases. If you find in some particular case that the value index is
not picked up when think it should be, you can replace the pikey index with separate
indexes for the paths and order relationships. Such (optional) indexes are called path
id and order key indexes, respectively. For best results, contact Oracle Support if you
find that the pikey index is not sufficient for your needs in some case.
The path table contains one row for each indexed node in the XML document. For each
indexed node, the path table stores:
■

The corresponding rowid of the table that stores the document.
Indexing XMLType Data

6-13

XMLIndex

A locator, which provides fast access to the corresponding document fragment. For
binary XML storage of XML schema-based data, it also stores data-type
information.

■

An order key, to record the hierarchical position of the node in the document. You
can think of this as a Dewey decimal key like that used in library cataloging and
Internet protocol SNMP. In such a system, the key 3.21.5 represents the node
position of the fifth child of the twenty-first child of the third child of the
document root node.

■

■

An identifier that represents an XPath path to the node.

■

The effective text value of the node.

Table 6–6 shows the main information2 that is in the path table.
Table 6–6

XMLIndex Path Table

Column

Data Type

Description

PATHID

RAW(8)

Unique identifier for the XPath path to the node.

RID

ROWID

Rowid of the table used to store the XML data.

ORDER_KEY RAW(1000)

Decimal order key that identifies the hierarchical position of
the node. (Document ordering is preserved.)

LOCATOR

RAW(2000)

Fragment-location information. Used for fragment
extraction. For binary XML storage of XML schema-based
data, data-type information is also stored here.

VALUE

VARCHAR2(4000) Effective text value the node.

The pikey index uses path table columns PATHID, RID, and ORDER_KEY to represent
the path and order indexes. An optional path id index uses columns PATHID and RID
to represent the path index. A value index is an index on the VALUE column.
Example 6–5 explores the contents of the path table for two purchase-order
documents.
Example 6–5 Path Table Contents for Two Purchase Orders

SBELL-2002100912333601PDT


SVOLLMAN


. . .


ABEL-20021127121040897PST


ZLOTKEY


KING

2

The actual path table implementation may be slightly different.

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. . .


An XMLIndex index on an XMLType table or column storing these purchase orders
includes a path table that has one row for each indexed node in the XML documents.
Suppose that the system assigns the following PATHIDs when indexing the nodes
according to their XPath expressions:
PATHID Indexed XPath
1

/PurchaseOrder

2

/PurchaseOrder/Reference

3

/PurchaseOrder/Actions

4

/PurchaseOrder/Actions/Action

5

/PurchaseOrder/Actions/Action/User

The resulting path table would then be something like this (column LOCATOR is not
shown):
PATHID RID ORDER_KEY VALUE
1

R1

1

SBELL-2002100912333601PDTSVOLLMAN

2

R1

1.1

SBELL-2002100912333601PDT

3

R1

1.2

SVOLLMAN

4

R1

1.2.1

SVOLLMAN

5

R1

1.2.1.1

SVOLLMAN

1

R2

1

ABEL-20021127121040897PSTZLOTKEYKING

2

R2

1.1

ABEL-20021127121040897PST

3

R2

1.2

ZLOTKEYKING

4

R2

1.2.1

ZLOTKEY

5

R2

1.2.1.1

ZLOTKEY

4

R2

1.2.2

KING

5

R2

1.2.2.1

KING

Ignore the Path Table – It Is Transparent
Though you can create secondary indexes on path-table columns, you can generally
ignore the path table itself. You cannot access the path table, other than to DESCRIBE it
and create (secondary) indexes on it. You need never explicitly gather statistics on the
path table. You need only collect statistics on the XMLIndex index or the base table on
which the XMLIndex index is defined; statistics are collected and maintained on the
path table and its secondary indexes transparently.
See Also: "Collecting Statistics on XMLIndex Objects for the
Cost-Based Optimizer" on page 6-37

Indexing XMLType Data

6-15

XMLIndex

Column VALUE of an XMLIndex Path Table
A secondary index on column VALUE is used with XPath expressions in a WHERE
clause that have predicates involving string matches. For example:
/PurchaseOrder[Reference/text() = "SBELL-2002100912333601PDT"]

Column VALUE stores the effective text value of an element or an attribute
node—comments and processing instructions are ignored during indexing.
■
■

■

For an attribute, the effective text value is the attribute value.
For a simple element (an element that has no children), the effective text value is
the concatenation of all of the text nodes of the element.
For a complex element (an element that has children), the effective text value is the
concatenation of (1) the text nodes of the element itself and (2) the effective text
values of all of its simple-element descendants. (This is a recursive definition.)

The effective text value is limited (truncated), however, to 4000 bytes for a simple
element or attribute and to 80 bytes for a complex element.
Column VALUE is a fixed size, VARCHAR2(4000). Any overflow (beyond 4000 bytes)
during index creation or update is truncated, but the LOCATOR value for that row is
then flagged so that the full value can be retrieved from the base table when needed.
In addition to the 4000-byte limit for column VALUE, there is a limit on the size of a key
for the secondary index created on this column. This is the case for B-tree and
function-based indexes as well; it is not an XMLIndex limitation. The index-key size
limit is a function of the block size for your database. It is this limit that determines
how much of VALUE is indexed.
Thus, only the first 4000 bytes of the effective text value are stored in column VALUE,
and only the first N bytes of column VALUE are indexed, where N is the index-key size
limit (N < 4000). Because of the index-key size limit, the index on column VALUE acts
only as a preliminary filter for the effective text value.
For example, suppose that your database block size requires that the VALUE index be
no larger than 800 bytes, so that only the first 800 bytes of the effective text value is
indexed. The first 800 bytes of the effective text value is first tested, using XMLIndex,
and only if that text prefix matches the query value is the rest of the effective text value
tested.
The secondary index on column VALUE is an index on SQL function substr
(substring equality), because that function is used to test the text prefix. This
function-based index is created automatically as part of the implementation of
XMLIndex for column VALUE.
For example, the XPath expression /PurchaseOrder[Reference/text() = :1]
in a query WHERE clause might, in effect, be rewritten to a test something like this:
substr(VALUE, 1 800) = substr(:1, 1, 800) AND VALUE = :1;

This conjunction contains two parts, which are processed from left to right. The first
test uses the index on function substr as a preliminary filter, to eliminate text whose
first 800 bytes do not match the first 800 bytes of the value of bind variable :1.
Only the first test uses an index—the full value of column VALUE is not indexed. After
preliminary filtering by the first test, the second test checks the entire effective text
value—that is, the full value of column VALUE—for full equality with the value of :1.
This check does not use an index.

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Even if only the first 800 bytes of text is indexed, it is important for query performance
that up to 4000 bytes be stored in column VALUE, because that provides quick, direct
access to the data, instead of requiring, for example, extracting it from deep within a
CLOB-instance XML document. If the effective text value is greater than 4000 bytes,
then the second test in the WHERE-clause conjunction requires accessing the base-table
data.
Note that neither the VALUE column 4000-byte limit nor the index-key size affect query
results in any way; they can affect only performance.
Because of the possibility of the VALUE column being
truncated, an Oracle Text CONTEXT index created on the VALUE
column might return incorrect results.

Note:

As mentioned, XMLIndex can be used with XML schema-based data. If an XML
schema specifies a defaultValue value for a given element or attribute, and a
particular document does not specify a value for that element or attribute, then the
defaultValue value is used for the VALUE column.

Secondary Indexes on Column VALUE
Even if you do not specify a secondary index for column VALUE when you create an
XMLIndex index, a default secondary index is created on column VALUE. This default
index has the default properties—in particular, it is an index for text (string-valued)
data only.
You can, however, create a VALUE index of a different type. For example, you can
create a number-valued index if that is appropriate for many of your queries. You can
create multiple secondary indexes on the VALUE column. An index of a particular type
is used only when it is appropriate. For example, a number-valued index is used only
when the VALUE column is a number; it is ignored for other values. Secondary indexes
on path-table columns are treated like any other secondary indexes—you can alter
them, drop them, mark them unusable, and so on.
See Also:
■

■

"Using XMLIndex with an Unstructured Component" on
page 6-19 for examples of creating secondary indexes on column
VALUE
"PARAMETERS Clause for CREATE INDEX and ALTER INDEX"
on page 6-38 for the syntax of the PARAMETERS clause

XPath Expressions that Are Not Indexed by an XMLIndex Unstructured Component
The following types of XPath expressions are not indexed by XMLIndex:
■

■

■

Applications of XPath functions, except ora:contains. In particular,
user-defined XPath functions are not indexed.
Axes other than child, descendant, and attribute, that is, axes parent,
ancestor, following-sibling, preceding-sibling, following,
preceding, and ancestor-or-self.
Expressions using the union operator, | (vertical bar).

Indexing XMLType Data

6-17

XMLIndex

Creating, Dropping, Altering, and Examining an XMLIndex Index
You create an XMLIndex index by declaring the index type to be XDB.XMLIndex, as
illustrated in Example 6–6.
Example 6–6 Creating an XMLIndex Index on XMLType Unstructured Storage
CREATE INDEX po_xmlindex_ix ON po_clob (OBJECT_VALUE) INDEXTYPE IS XDB.XMLIndex;

This creates an XMLIndex index named po_xmlindex_ix on XMLType table po_
clob. The index has only an unstructured component, no structured component.
You specify inclusion of a structured component in an XMLIndex index by including a
structured_clause in the PARAMETERS clause. You specify inclusion of an
unstructured component by including a path_table_clause in the PARAMETERS
clause. You can do this when you create the XMLIndex index or when you modify it.
If, as in Example 6–6, you specify neither a structured_clause nor a path_
table_clause, then only an unstructured component is included.
If an XMLIndex index has both an unstructured and a structured component, then you
can drop either of these components using ALTER INDEX.
See Also:
■

"PARAMETERS Clause for CREATE INDEX and ALTER INDEX"
on page 6-38

■

"structured_clause ::=" on page 6-42

■

"path_table_clause ::=" on page 6-41

■

"drop_path_table_clause ::=" on page 6-41

■

"alter_index_group_clause ::=" on page 6-43

You can obtain the name of an XMLIndex index on a particular XMLType table (or
column), as shown in Example 6–7. You can also select INDEX_NAME from DBA_
INDEXES or ALL_INDEXES, as appropriate.
Example 6–7 Obtaining the Name of an XMLIndex Index on a Particular Table
SELECT INDEX_NAME FROM USER_INDEXES
WHERE TABLE_NAME = 'PO_CLOB' AND ITYP_NAME = 'XMLINDEX';
INDEX_NAME
--------------PO_XMLINDEX_IX
1 row selected.

You rename or drop an XMLIndex index just as you would any other index, as
illustrated in Example 6–8. This renaming changes the name of the XMLIndex index
only. It does not change the name of the path table—you can rename the path table
separately.
Example 6–8 Renaming and Dropping an XMLIndex Index
ALTER INDEX po_xmlindex_ix RENAME TO new_name_ix;
DROP INDEX new_name_ix;

6-18 Oracle XML DB Developer's Guide

XMLIndex

Similarly, you can change other index properties using other ALTER INDEX options,
such as REBUILD. XMLIndex is no different from other index types in this respect.
The RENAME clause of an ALTER INDEX statement for XMLIndex applies only to the
XMLIndex index itself. To rename the path table and secondary indexes, you must
determine the names of these objects and use appropriate ALTER TABLE or ALTER
INDEX statements on them directly. Similarly, to retrieve the physical properties of the
secondary indexes or alter them in any other way, you must obtain their names, as in
Example 6–13.
Example 6–6 shows how to create an XMLIndex index on unstructured storage.
See Also: "PARAMETERS Clause for CREATE INDEX and ALTER
INDEX" on page 6-38 for the syntax of the PARAMETERS clause

Using XMLIndex with an Unstructured Component
This section covers operations you can perform on an XMLIndex index that has an
unstructured component (whether or not it also has a structured component)—see
"XMLIndex Unstructured Component" on page 6-13.
To include an unstructured component in an XMLIndex index, you use a path_
table_clause in the PARAMETERS clause when you create or modify the XMLIndex
index—see "path_table_clause ::=" on page 6-41.
If you do not specify a structured component, then the index will have an unstructured
component, even if you do not specify the path table. It is however generally a good
idea to specify the path table, so that it has a recognizable, user-oriented name that you
can refer to in other XMLIndex operations.
Example 6–9 shows how to name the path table ("my_path_table") when creating an
XMLIndex index with an unstructured component.
Example 6–9 Naming the Path Table of an XMLIndex Index
CREATE INDEX po_xmlindex_ix ON po_clob (OBJECT_VALUE) INDEXTYPE IS XDB.XMLIndex
PARAMETERS ('PATH TABLE my_path_table');

If you do not name the path table then its name is generated by the system, using the
index name you provide to CREATE INDEX as a base. Example 6–10 shows this for the
XMLIndex index created in Example 6–6.
Example 6–10

Determining the System-Generated Name of an XMLIndex Path Table

SELECT PATH_TABLE_NAME FROM USER_XML_INDEXES
WHERE TABLE_NAME = 'PO_CLOB' AND INDEX_NAME = 'PO_XMLINDEX_IX';
PATH_TABLE_NAME
-----------------------------SYS67567_PO_XMLINDE_PATH_TABLE
1 row selected.

By default, the storage options of a path table and its secondary indexes are derived
from the storage properties of the base table on which the XMLIndex index is created.
You can specify different storage options by using a PARAMETERS clause when you
create the index, as shown in Example 6–11. The PARAMETERS clause of CREATE
INDEX (and ALTER INDEX) must be between single quotation marks (').

Indexing XMLType Data

6-19

XMLIndex

See Also: "PARAMETERS Clause for CREATE INDEX and ALTER
INDEX" on page 6-38 for the syntax of the PARAMETERS clause
Example 6–11

Specifying Storage Options When Creating an XMLIndex Index

CREATE INDEX po_xmlindex_ix ON po_clob (OBJECT_VALUE) INDEXTYPE IS XDB.XMLIndex
PARAMETERS
('PATH TABLE po_path_table
(PCTFREE 5 PCTUSED 90 INITRANS 5
STORAGE (INITIAL 1k NEXT 2k MINEXTENTS 3 BUFFER_POOL KEEP)
NOLOGGING ENABLE ROW MOVEMENT PARALLEL 3)
PIKEY INDEX po_pikey_ix (LOGGING PCTFREE 1 INITRANS 3)
VALUE INDEX po_value_ix (LOGGING PCTFREE 1 INITRANS 3)');

Because XMLIndex is a logical domain index, not a physical index, all physical
attributes are either zero (0) or NULL.
If an XMLIndex index has both an unstructured and a structured component, then you
can use ALTER INDEX to drop the unstructured component. To do this, you drop the
path table. Example 6–12 illustrates this. (This assumes that you also have a structured
component—Example 6–20 results in an index with both structured and unstructured
components.)
Example 6–12

Dropping an XMLIndex Unstructured Component

ALTER INDEX po_xmlindex_ix PARAMETERS('DROP PATH TABLE');

Note that, in addition to specifying storage options for the path table, Example 6–11
names the secondary indexes on the path table.
Like the name of the path table, the names of the secondary indexes on the path-table
columns are generated automatically using the index name as a base, unless you
specify them in the PARAMETERS clause. Example 6–13 illustrates this, and shows how
you can determine these names using public view USER_IND_COLUMNS. It also shows
that the pikey index uses three columns.
Example 6–13

Determining the Names of the Secondary Indexes of an XMLIndex Index

SELECT INDEX_NAME, COLUMN_NAME, COLUMN_POSITION FROM USER_IND_COLUMNS
WHERE TABLE_NAME IN (SELECT PATH_TABLE_NAME FROM USER_XML_INDEXES
WHERE INDEX_NAME = 'PO_XMLINDEX_IX')
ORDER BY INDEX_NAME, COLUMN_NAME;
INDEX_NAME
-----------------------------SYS67563_PO_XMLINDE_PIKEY_IX
SYS67563_PO_XMLINDE_PIKEY_IX
SYS67563_PO_XMLINDE_PIKEY_IX
SYS67563_PO_XMLINDE_VALUE_IX

COLUMN_NAME COLUMN_POSITION
------------ --------------ORDER_KEY
3
PATHID
2
RID
1
SYS_NC00006$
1

4 rows selected.

See Also: Example 6–19 on page 6-22 for a similar, but more
complex example

Creating Additional Secondary Indexes on an XMLIndex Path Table
This section adds extra secondary indexes to the XMLIndex index created in
Example 6–11.

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XMLIndex

You can create any number of additional secondary indexes on the VALUE column of
the path table of an XMLIndex index. These can be of different types, including
function-based indexes and Oracle Text indexes.
Whether or not a given index is used for a given element occurrence when processing
a query is determined by whether it is of the appropriate type for that value and
whether it is cost-effective to use it.
Example 6–14 creates a function-based index on column VALUE of the path table using
SQL function substr. This might be useful if your queries often use substr applied
to the text nodes of XML elements.
Example 6–14

Creating a Function-Based Index on Path-Table Column VALUE

CREATE INDEX fn_based_ix ON po_path_table (substr(VALUE, 1, 100));

If you have many elements whose text nodes represent numeric values, then it can
make sense to create a numeric index on the column VALUE. However, doing so
directly, in a manner analogous to Example 6–14, raises an ORA-01722 error (invalid
number) if some of the element values are not numbers. This is illustrated in
Example 6–15.
Example 6–15

Trying to Create a Numeric Index on Path-Table Column VALUE Directly

CREATE INDEX direct_num_ix ON po_path_table (to_binary_double(VALUE));
CREATE INDEX direct_num_ix ON po_path_table (to_binary_double(VALUE))
*
ERROR at line 1:
ORA-01722: invalid number

What is needed is an index that is used for numeric-valued elements but is ignored for
element occurrences that do not have numeric values. Procedure
createNumberIndex of package DBMS_XMLINDEX exists specifically for this
purpose. You pass it the names of the database schema, the XMLIndex index, and the
numeric index to be created. Creation of a numeric index is illustrated in
Example 6–16.
Example 6–16 Creating a Numeric Index on Column VALUE with Procedure
createNumberIndex
CALL DBMS_XMLINDEX.createNumberIndex('OE', 'PO_XMLINDEX_IX', 'API_NUM_IX');

Note that because such an index is specifically designed to ignore elements that do not
have numeric values, its use does not detect their presence. If there are non-numeric
elements and, for whatever reason, the XMLIndex index is not used in some query,
then an ORA-01722 error is raised. However, if the index is used, no such error is
raised, because the index ignores non-numeric data. As always, the use of an index
never changes the result set—it never gives you different results, but use of an index
can prevent you from detecting erroneous data.
Creating a date-valued index is similar to creating a numeric index; you use procedure
DBMS_XMLINDEX.createDateIndex. Example 6–17 shows this.
Example 6–17

Creating a Date Index on Column VALUE with Procedure createDateIndex

CALL DBMS_XMLINDEX.createDateIndex('OE', 'PO_XMLINDEX_IX', 'API_DATE_IX',
'dateTime');

Example 6–18 creates an Oracle Text CONTEXT index on column VALUE. This is useful
for full-text queries on text values of XML elements. XPath predicates that use XPath
Indexing XMLType Data

6-21

XMLIndex

function ora:contains are rewritten to applications of Oracle SQL function
contains on column VALUE. If a CONTEXT index is defined on column VALUE, then it
is used during predicate evaluation. An Oracle Text index is independent of all other
VALUE-column indexes.
Example 6–18

Creating an Oracle Text CONTEXT Index on Path-Table Column VALUE

CREATE INDEX po_otext_ix ON po_path_table (VALUE)
INDEXTYPE IS CTXSYS.CONTEXT PARAMETERS('TRANSACTIONAL');

See Also:
■

■

"Column VALUE of an XMLIndex Path Table" on page 6-16 for
information about the possibility of an Oracle Text CONTEXT index
created on the VALUE column returning incorrect results
"Oracle Text Indexes on XML Data" on page 6-46

The query in Example 6–19 shows all of the secondary indexes created on the path
table of an XMLIndex index. The indexes created explicitly are in bold. Note in
particular that some indexes, such as the function-based index created on column
VALUE, do not appear as such; the column name listed for such an index is a
system-generated name such as SYS_NC00007$. You cannot see these columns by
executing a query with COLUMN_NAME = 'VALUE' in the WHERE clause.
Example 6–19

Showing All Secondary Indexes on an XMLIndex Path Table

SELECT c.INDEX_NAME, c.COLUMN_NAME, c.COLUMN_POSITION, e.COLUMN_EXPRESSION
FROM USER_IND_COLUMNS c LEFT OUTER JOIN USER_IND_EXPRESSIONS e
ON (c.INDEX_NAME = e.INDEX_NAME)
WHERE c.TABLE_NAME IN (SELECT PATH_TABLE_NAME FROM USER_XML_INDEXES
WHERE INDEX_NAME = 'PO_XMLINDEX_IX')
ORDER BY c.INDEX_NAME, c.COLUMN_NAME;
INDEX_NAME
COLUMN_NAME COLUMN_POSITION COLUMN_EXPRESSION
-------------------- ------------ --------------- ---------------------API_DATE_IX
SYS_NC00009$
1 SYS_EXTRACT_UTC(SYS_XMLCONV("V
ALUE",3,8,0,0,181))
API_NUM_IX
SYS_NC00008$
1 TO_BINARY_DOUBLE("VALUE")
FN_BASED_IX
SYS_NC00007$
1 SUBSTR("VALUE",1,100)
PO_OTEXT_IX
VALUE
1
PO_PIKEY_IX
ORDER_KEY
3
PO_PIKEY_IX
PATHID
2
PO_PIKEY_IX
RID
1
PO_VALUE_IX
SYS_NC00006$
1 SUBSTRB("VALUE",1,1599)
8 rows selected.

See Also:
■

■

Oracle Database PL/SQL Packages and Types Reference for
information on PL/SQL procedures createNumberIndex and
createDateIndex in package DBMS_XMLINDEX
"Oracle Text Indexes Are Used Independently of Other Indexes"
on page 6-47 for information on using Oracle Text indexes

6-22 Oracle XML DB Developer's Guide

XMLIndex

Using XMLIndex with a Structured Component
To include a structured component in an XMLIndex index, you use a structured_
clause in the PARAMETERS clause when you create or modify the XMLIndex
index—see "structured_clause ::=" on page 6-42.
A structured_clause specifies the structured islands that you want to index. You
use the keyword GROUP to specify each structured island: an island thus corresponds
syntactically to a structure group. If you specify no group explicitly, then the
predefined group DEFAULT_GROUP is used. For ALTER INDEX, you precede the
GROUP keyword with the modification operation keyword: ADD_GROUP specifies a
new group (island); DROP_GROUP deletes a group.
Why have multiple groups within a single index, instead of simply using multiple
XMLIndex indexes? The reason is that XMLIndex is a domain index, and you can
create only one domain index of a given type on a given database column.
The syntax for defining a structure group, that is, indexing a structured island, is
similar to the syntax for invoking SQL/XML function XMLTable: you use keywords
XMLTable and COLUMNS to define relational columns, and you use multilevel
chaining of XMLTable to handle collections.
Example 6–20 shows the creation of an XMLIndex index with only an unstructured
component. An unstructured component is created because the PARAMETERS clause
explicitly names the path table.
Example 6–20 then uses ALTER INDEX to add a structured component (group) named
po_item. This structure group includes two relational tables, each specified with
keyword XMLTable.
Example 6–20

XMLIndex Index: Adding a Structured Component

CREATE INDEX po_xmlindex_ix ON po_clob (OBJECT_VALUE)
INDEXTYPE IS XDB.XMLIndex PARAMETERS ('PATH TABLE path_tab');
BEGIN
DBMS_XMLINDEX.registerParameter(
'myparam',
'ADD_GROUP GROUP po_item
XMLTable po_idx_tab ''/PurchaseOrder''
COLUMNS reference
VARCHAR2(30) PATH
requestor
VARCHAR2(30) PATH
username
VARCHAR2(30) PATH
lineitem
XMLType
PATH
XMLTable po_index_lineitem ''/LineItem''
COLUMNS itemno
BINARY_DOUBLE PATH
description VARCHAR2(256) PATH
partno
VARCHAR2(14) PATH
quantity
BINARY_DOUBLE PATH
unitprice
BINARY_DOUBLE PATH
END;
/

''Reference'',
''Requestor'',
''User'',
''LineItems/LineItem'' VIRTUAL
PASSING lineitem
''@ItemNumber'',
''Description'',
''Part/@Id'',
''Part/@Quantity'',
''Part/@UnitPrice''');

ALTER INDEX po_xmlindex_ix PARAMETERS('PARAM myparam');

The top-level table, po_idx_tab, has columns reference, requestor, username,
and lineitem. Column lineitem is of type XMLType. It represents a collection, so it
is passed to the second XMLTable construct to form the second-level relational table,
po_index_lineitem, which has columns itemno, description, partno,
quantity, and unitprice.

Indexing XMLType Data

6-23

XMLIndex

The keyword VIRTUAL is required for an XMLType column. It specifies that the
XMLType column itself is not materialized: its data is stored in the XMLIndex index
only in the form of the relational columns specified by its corresponding XMLTable
table.
You cannot create more than one XMLType column in a given XMLTable clause. To
achieve that effect, you must instead define an additional group.
Example 6–20 also illustrates the use of a registered parameter string in the
PARAMETERS clause. It uses PL/SQL procedure DBMS_
XMLINDEX.registerParameter to register the parameters string named myparam.
Then it uses ALTER INDEX to update the index parameters to include those in the
string myparam.
If an XMLIndex index has both an unstructured and a structured component, then you
can use ALTER INDEX to drop the structured component. You do this by dropping all
of the structure groups that compose the structured component. Example 6–21 shows
how to drop the structured component that was added in Example 6–20, by dropping
its only structure group, po_item.
Example 6–21

Dropping an XMLIndex Structured Component

ALTER INDEX po_xmlindex_ix PARAMETERS('DROP_GROUP GROUP po_item');

As indicated in section "XMLIndex Structured Component" on page 6-10, because the
tables used for the structured component of an XMLIndex index are normal relational
tables, you can index them using any standard relational indexes.
Example 6–22 and Example 6–23 illustrate this: Example 6–22 creates a B-tree index on
the reference column of the index content table (structured fragment) for the
XMLIndex index of Example 6–20. Example 6–23 creates an Oracle Text CONTEXT
index on the description column and then uses a full-text query on the content.
Example 6–22

Creating a B-Tree Index on an XMLIndex Index Content Table

CREATE INDEX idx_tab_ref_ix ON po_idx_tab (reference);
Example 6–23

Oracle Text CONTEXT Index on an XMLIndex Index Content Table

CREATE INDEX idx_tab_desc_ix ON po_index_lineitem (description)
INDEXTYPE IS CTXSYS.CONTEXT PARAMETERS ('transactional');
SELECT XMLQuery('/PurchaseOrder/LineItems/LineItem'
PASSING OBJECT_VALUE RETURNING CONTENT)
FROM po_clob
WHERE XMLExists('/PurchaseOrder/LineItems/LineItem
[ora:contains(Description, "Picnic") > 0]'
PASSING OBJECT_VALUE)
AND XMLExists('/PurchaseOrder[User="SBELL"]' PASSING OBJECT_VALUE);

Example 6–24 shows the creation of an XMLIndex index that has only a structured
component (no path table clause) and that uses the XMLNAMESPACES clause to specify
namespaces. It specifies that the index data be compressed and use tablespace
SYSAUX. The example assumes a binary XML table po_binxml with non XML
schema-based data.
Example 6–24

XMLIndex with Only a Structured Component and using Namespaces

CREATE INDEX po_struct ON po_binxml (OBJECT_VALUE) INDEXTYPE IS XDB.XMLIndex
PARAMETERS ('XMLTable po_ptab

6-24 Oracle XML DB Developer's Guide

XMLIndex

(TABLESPACE "SYSAUX" COMPRESS FOR OLTP)
XMLNAMESPACES (DEFAULT ''http://www.example.com/po''),
''/purchaseOrder''
COLUMNS orderdate
DATE
PATH ''@orderDate'',
id
BINARY_DOUBLE PATH ''@id'',
items
XMLType
PATH ''items/item'' VIRTUAL
XMLTable li_tab
(TABLESPACE "SYSAUX" COMPRESS FOR OLTP)
XMLNAMESPACES (DEFAULT ''http://www.example.com/po''),
''/item'' PASSING items
COLUMNS partnum
VARCHAR2(15) PATH ''@partNum'',
description CLOB
PATH ''productName'',
usprice
BINARY_DOUBLE PATH ''USPrice'',
shipdat
DATE
PATH ''shipDate''');

See Also:
■

■
■

■
■

■

■

Example 6–28, "Using a Structured XMLIndex Component for a
Query with Two Predicates" on page 6-28
"Oracle Text Indexes on XML Data" on page 6-46
"Using a Registered PARAMETERS Clause for XMLIndex" on
page 6-39
"structured_clause ::=" on page 6-42
"Usage of XMLIndex_xmltable_clause" on page 6-45 for
information about an XMLType column in an XMLTable clause
"Usage of column_clause" on page 6-46 for information about
keywords COLUMNS and VIRTUAL
"Data Type Considerations for XMLIndex Structured Component"
on page 6-11

How to Tell Whether XMLIndex is Used
It is at query compile time that Oracle Database determines whether or not a given
XMLIndex index can be used, that is, whether the query can be rewritten into a query
against the index.
For an unstructured XMLIndex component, if it cannot be determined at compile time
that an XPath expression in the query is a subset of the paths you specified to be used
for XMLIndex indexing, then the unstructured component of the index is not used.
For example, if the path /PurchaseOrder/LineItems//* is included for indexing,
then a query with /PurchaseOrder/LineItems/LineItem/Description can
use the index, but a query with //Description cannot. The latter also matches
potential Description elements that are not children of
/PurchaseOrder/LineItems, and it is not possible at compile time to know if such
additional Description elements are present in the data.
To know whether a particular XMLIndex index has been used in resolving a query,
you can examine an execution plan for the query.
■

■

If the unstructured component of the index is used, then its path table, order key, or
path id is referenced in the execution plan. The execution plan does not directly
indicate that a domain index was used; it does not refer to the XMLIndex index by
name. See Example 6–25 on page 6-26 and Example 6–27 on page 6-27.
If the structured component of the index is used, then one or more of its index
content tables is called out in the execution plan. See Example 6–28 on page 6-28
Indexing XMLType Data

6-25

XMLIndex

and Example 6–29 on page 6-29.
See Also:
■

Oracle Database SQL Language Reference

■

Oracle Database Performance Tuning Guide

Example 6–25 shows that the XMLIndex index created in Example 6–9 is used in a
particular query. The reference to MY_PATH_TABLE in the execution plan here
indicates that the XMLIndex index (created in Example 6–9) is used in this query.
Similarly, reference to columns LOCATOR, ORDER_KEY, and PATHID indicates the same
thing.
Example 6–25

Checking Whether an XMLIndex Unstructured Component Is Used

SET AUTOTRACE ON EXPLAIN
SELECT XMLQuery('/PurchaseOrder/Requestor' PASSING OBJECT_VALUE RETURNING CONTENT) FROM po_clob
WHERE XMLExists('/PurchaseOrder[Reference="SBELL-2002100912333601PDT"]' PASSING OBJECT_VALUE);
XMLQUERY('/PURCHASEORDER/REQUESTOR'PASSINGOBJECT_VALUERETURNINGCONTENT)
----------------------------------------------------------------------Sarah J. Bell
1 row selected.

Execution Plan
. . .
---------------------------------------------------------------------------------------------------------------| Id | Operation
| Name
| Rows | Bytes | Cost (%CPU)| Time
|
---------------------------------------------------------------------------------------------------------------|
0 | SELECT STATEMENT
|
|
1 |
24 |
28
(4)| 00:00:01 |
|
1 | SORT GROUP BY
|
|
1 | 3524 |
|
|
|* 2 |
TABLE ACCESS BY INDEX ROWID
| MY_PATH_TABLE
|
2 | 7048 |
3
(0)| 00:00:01 |
|* 3 |
INDEX RANGE SCAN
| SYS67616_PO_XMLINDE_PIKEY_IX |
1 |
|
2
(0)| 00:00:01 |
|
4 | NESTED LOOPS
|
|
1 |
24 |
28
(4)| 00:00:01 |
|
5 |
VIEW
| VW_SQ_1
|
1 |
12 |
26
(0)| 00:00:01 |
|
6 |
HASH UNIQUE
|
|
1 | 5046 |
|
|
|
7 |
NESTED LOOPS
|
|
1 | 5046 |
26
(0)| 00:00:01 |
|* 8 |
TABLE ACCESS BY INDEX ROWID| MY_PATH_TABLE
|
1 | 3524 |
24
(0)| 00:00:01 |
|* 9 |
INDEX RANGE SCAN
| SYS67616_PO_XMLINDE_VALUE_IX |
73 |
|
1
(0)| 00:00:01 |
|* 10 |
TABLE ACCESS BY INDEX ROWID| MY_PATH_TABLE
|
1 | 1522 |
2
(0)| 00:00:01 |
|* 11 |
INDEX RANGE SCAN
| SYS67616_PO_XMLINDE_PIKEY_IX |
1 |
|
1
(0)| 00:00:01 |
| 12 |
TABLE ACCESS BY USER ROWID
| PO_CLOB
|
1 |
12 |
1
(0)| 00:00:01 |
---------------------------------------------------------------------------------------------------------------Predicate Information (identified by operation id):
--------------------------------------------------2 - filter(SYS_XMLI_LOC_ISNODE("SYS_P0"."LOCATOR")=1)
3 - access("SYS_P0"."RID"=:B1 AND "SYS_P0"."PATHID"=HEXTORAW('76E2') )
8 - filter("SYS_P4"."VALUE"='SBELL-2002100912333601PDT' AND "SYS_P4"."PATHID"=HEXTORAW('4F8C') AND
SYS_XMLI_LOC_ISNODE("SYS_P4"."LOCATOR")=1)
9 - access(SUBSTRB("VALUE",1,1599)='SBELL-2002100912333601PDT')
10 - filter(SYS_XMLI_LOC_ISNODE("SYS_P2"."LOCATOR")=1)
11 - access("SYS_P4"."RID"="SYS_P2"."RID" AND "SYS_P2"."PATHID"=HEXTORAW('4E36') AND
"SYS_P2"."ORDER_KEY"<"SYS_P4"."ORDER_KEY")
filter("SYS_P4"."ORDER_KEY":B2 AND
"SYS_P2"."ORDER_KEY":B2 AND
"SYS_P5"."ORDER_KEY" 0]' PASSING OBJECT_VALUE)
AND XMLEXists('/PurchaseOrder[User="SBELL"]' PASSING OBJECT_VALUE);
------------------------------------------------------------------------------------------------------------| Id | Operation
| Name
| Rows | Bytes | Cost (%CPU)| Time
|
------------------------------------------------------------------------------------------------------------|
0 | SELECT STATEMENT
|
|
1 |
189 |
22 (14)| 00:00:01 |
|
1 | SORT GROUP BY
|
|
1 | 3524 |
|
|
|* 2 |
TABLE ACCESS BY INDEX ROWID| PATH_TAB
|
2 | 7048 |
3
(0)| 00:00:01 |
|* 3 |
INDEX RANGE SCAN
| SYS67840_PO_XMLINDE_PIKEY_IX |
1 |
|
2
(0)| 00:00:01 |
|* 4 | HASH JOIN SEMI
|
|
1 |
189 |
22 (14)| 00:00:01 |
|
5 |
NESTED LOOPS
|
|
13 |
637 |
4 (25)| 00:00:01 |

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XMLIndex

|
6 |
SORT UNIQUE
|
|
13 |
351 |
3
(0)| 00:00:01 |
|* 7 |
TABLE ACCESS FULL
| PO_IDX_TAB
|
13 |
351 |
3
(0)| 00:00:01 |
|* 8 |
INDEX UNIQUE SCAN
| SYS_C006004
|
1 |
22 |
0
(0)| 00:00:01 |
|* 9 |
TABLE ACCESS FULL
| PO_INDEX_LINEITEM
|
13 | 1820 |
17
(6)| 00:00:01 |
------------------------------------------------------------------------------------------------------------Predicate Information (identified by operation id):
--------------------------------------------------2
3
4
7
8
9

-

filter(SYS_XMLI_LOC_ISNODE("SYS_P0"."LOCATOR")=1)
access("SYS_P0"."RID"=:B1 AND "SYS_P0"."PATHID"=HEXTORAW('3748') )
access("SYS_ALIAS_1"."SYS_NC_OID$"="SYS_ALIAS_3"."OID")
filter("SYS_ALIAS_2"."USERNAME"='SBELL')
access("SYS_ALIAS_1"."SYS_NC_OID$"="SYS_ALIAS_2"."OID")
filter(SYS_XMLCONTAINS("SYS_ALIAS_3"."DESCRIPTION",'Picnic')>0)

Note
----- dynamic sampling used for this statement (level=2)
- Unoptimized XML construct detected (enable XMLOptimizationCheck for more information)
30 rows selected.

The presence in Example 6–28 of the path table name, path_tab, indicates that the
unstructured index component of the index is used. The presence of the index content
table po_idx_tab indicates that the structured index component is used.
Example 6–29 shows an execution plan that indicates that the same XMLIndex index is
also picked up for a query that uses multilevel XMLTable chaining. With only the
unstructured XMLIndex component, this query too would involve a join of the path
table to itself, because of the different paths in the two XMLTable function calls.
Example 6–29

Using a Structured XMLIndex Component for a Query with Multilevel Chaining

EXPLAIN PLAN FOR
SELECT po.reference, li.*
FROM po_clob p,
XMLTable('/PurchaseOrder' PASSING p.OBJECT_VALUE
COLUMNS reference
VARCHAR2(30) PATH 'Reference',
lineitem
XMLType
PATH 'LineItems/LineItem') po,
XMLTable('/LineItem' PASSING po.lineitem
COLUMNS itemno
BINARY_DOUBLE PATH '@ItemNumber',
description VARCHAR2(256) PATH 'Description',
partno
VARCHAR2(14) PATH 'Part/@Id',
quantity
BINARY_DOUBLE PATH 'Part/@Quantity',
unitprice
BINARY_DOUBLE PATH 'Part/@UnitPrice') li
WHERE po.reference = 'SBELL-20021009123335280PDT';
------------------------------------------------------------------------------------------------------| Id | Operation
| Name
| Rows | Bytes | Cost (%CPU)| Time
|
------------------------------------------------------------------------------------------------------|
0 | SELECT STATEMENT
|
|
17 | 20366 |
11
(0)| 00:00:01 |
|
1 | NESTED LOOPS
|
|
|
|
|
|
|
2 |
NESTED LOOPS
|
|
17 | 20366 |
11
(0)| 00:00:01 |
|
3 |
NESTED LOOPS
|
|
1 |
539 |
3
(0)| 00:00:01 |
|* 4 |
TABLE ACCESS FULL
| PO_IDX_TAB
|
1 |
529 |
3
(0)| 00:00:01 |
|* 5 |
INDEX UNIQUE SCAN
| SYS_C006320
|
1 |
10 |
0
(0)| 00:00:01 |
|* 6 |
INDEX RANGE SCAN
| SYS69412_69421_PKY_IDX |
17 |
|
1
(0)| 00:00:01 |
|
7 |
TABLE ACCESS BY INDEX ROWID| PO_INDEX_LINEITEM
|
17 | 11203 |
8
(0)| 00:00:01 |
------------------------------------------------------------------------------------------------------Predicate Information (identified by operation id):
---------------------------------------------------

Indexing XMLType Data

6-29

XMLIndex

4 - filter("SYS_ALIAS_8"."REFERENCE"='SBELL-20021009123335280PDT')
5 - access("SYS_ALIAS_8"."OID"="P"."SYS_NC_OID$")
6 - access("SYS_ALIAS_8"."KEY"="SYS_ALIAS_9"."PKEY")
Note
----- dynamic sampling used for this statement
25 rows selected.

The execution plan shows direct access to the relational index content tables, po_idx_
tab and po_index_lineitem. There is no access at all to the path table, path_tab.
See Also: "Collecting Statistics on XMLIndex Objects for the
Cost-Based Optimizer" on page 6-37

Turning Off Use of XMLIndex
You can turn off the use of XMLIndex in any of these ways:
■

Use optimizer hint /*+ NO_XML_QUERY_REWRITE */

■

Use optimizer hint /*+ NO_XMLINDEX_REWRITE */

Hints NO_XML_QUERY_REWRITE and NO_XMLINDEX_REWRITE turn off the use of all
XMLIndex indexes. In addition to turning off use of XMLIndex, NO_XML_QUERY_
REWRITE turns off all XQuery optimization (XMLIndex is part of XPath rewrite).
Example 6–30 shows the use of these optimizer hints.
Example 6–30

Turning Off XMLIndex using Optimizer Hints

SELECT /*+ NO_XMLINDEX_REWRITE */
count(*) FROM po_clob WHERE XMLExists('$p/*' PASSING OBJECT_VALUE AS "p");
SELECT /*+ NO_XML_QUERY_REWRITE */
count(*) FROM po_clob WHERE XMLExists('$p/*' PASSING OBJECT_VALUE AS "p");

Note:

The NO_INDEX optimizer hint does not apply to XMLIndex.

See Also:
■

■

"XQuery Optional Features" on page 5-43 for information about
XQuery pragmas ora:xq_proc and ora:xq_qry, which you
can use for fine-grained control of XQuery optimization
"How Oracle XML DB Processes XMLType Methods and SQL
Functions" on page 3-58 for information about streaming
evaluation of binary XML data

XMLIndex Path Subsetting: Specifying the Paths You Want to Index
One of the advantages of an XMLIndex index with an unstructured component is that
it is very general: you need not specify which XPath locations to index; you need no
prior knowledge of the XPath expressions that will be queried. By default, an
unstructured XMLIndex indexes all possible XPath locations in your XML data.
However, if you are aware of the XPath expressions that you are most likely to query,
then you can narrow the focus of XMLIndex indexing and thus improve performance.
Having fewer indexed nodes means less space is required for indexing, which
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XMLIndex

improves index maintenance during DML operations. Having fewer indexed nodes
improves DDL performance, and having a smaller path table improves query
performance.
You narrow the focus of indexing by pruning the set of XPath expressions (paths)
corresponding to XML fragments to be indexed, specifying a subset of all possible
paths. You can do this in two alternative ways:
■

■

Exclusion – Start with the default behavior of including all possible XPath
expressions, and exclude some of them from indexing.
Inclusion – Start with an empty set of XPath expressions to be used in indexing,
and add paths to this inclusion set.

You can specify path subsetting either when you create an XMLIndex index using
CREATE INDEX or when you modify it using ALTER INDEX. In both cases, you
provide the subsetting information in the PATHS parameter of the statement's
PARAMETERS clause. For exclusion, you use keyword EXCLUDE. For inclusion, you use
keyword INCLUDE for ALTER INDEX and no keyword for CREATE INDEX (list the
paths to include). You can also specify namespace mappings for the nodes targeted by
the PATHS parameter.
For ALTER INDEX, keyword INCLUDE or EXCLUDE is followed by keyword ADD or
REMOVE, to indicate whether the list of paths that follows the keyword is to be added
or removed from the inclusion or exclusion list. For example, this statement adds path
/PurchaseOrder/Reference to the list of paths to be excluded from indexing:
ALTER INDEX po_xmlindex_ix REBUILD
PARAMETERS ('PATHS (EXCLUDE ADD (/PurchaseOrder/Reference))');

To alter an XMLIndex index so that it includes all possible paths, use keyword INDEX_
ALL_PATHS. See "alter_index_paths_clause ::=" on page 6-40.

If you create an XMLIndex index that has both structured and
unstructured components, then, by default, any nodes indexed in the
structured component are also indexed in the unstructured
component; that is, they are not automatically excluded from the
unstructured component. If you do not want unstructured XMLIndex
indexing to apply to them, then you must explicitly use path
subsetting to exclude them.
Note:

See Also: "PARAMETERS Clause for CREATE INDEX and ALTER
INDEX" on page 6-38 for the syntax of the PARAMETERS clause

Examples of XMLIndex Path Subsetting
This section presents some examples of defining XMLIndex indexes on subsets of
XPath expressions.
Example 6–31

XMLIndex Path Subsetting with CREATE INDEX

CREATE INDEX po_xmlindex_ix ON po_clob (OBJECT_VALUE) INDEXTYPE IS XDB.XMLINDEX
PARAMETERS ('PATHS (INCLUDE (/PurchaseOrder/LineItems//*
/PurchaseOrder/Reference))');

This statement creates an index that indexes only top-level element PurchaseOrder
and some of its children, as follows:

Indexing XMLType Data

6-31

XMLIndex

■

All LineItems elements and their descendants

■

All Reference elements

It does that by including the specified paths, starting with an empty set of paths to be
used for the index.
Example 6–32

XMLIndex Path Subsetting with ALTER INDEX

ALTER INDEX po_xmlindex_ix REBUILD
PARAMETERS ('PATHS (INCLUDE ADD (/PurchaseOrder/Requestor
/PurchaseOrder/Actions/Action//*))');

This statement adds two more paths to those used for indexing. These paths index
element Requestor and descendants of element Action (and their ancestors).
Example 6–33

XMLIndex Path Subsetting using a Namespace Prefix

If an XPath expression to be used for XMLIndex indexing uses namespace prefixes,
you can use a NAMESPACE MAPPING clause to the PATHS list, to specify those prefixes.
Here is an example:
CREATE INDEX po_xmlindex_ix ON po_clob (OBJECT_VALUE) INDEXTYPE IS XDB.XMLIndex
PARAMETERS ('PATHS (INCLUDE (/PurchaseOrder/LineItems//*
/PurchaseOrder/ipo:Reference)
NAMESPACE MAPPING (xmlns="http://xmlns.oracle.com"
xmlns:ipo="http://xmlns.oracle.com/ipo"))');

XMLIndex Path-Subsetting Rules
The following rules apply to XMLIndex path subsetting:
■

■

■

The paths must reference only child and descendant axes, and they must test only
element and attribute nodes or their names (possibly using wildcards). In
particular, the paths must not involve predicates.
You cannot specify both path exclusion and path inclusion; choose one or the
other.
If an index was created using path exclusion (inclusion), then you can modify it
using only path exclusion (inclusion)—index modification must either further
restrict or further extend the path subset. For example, you cannot create an index
that includes certain paths and subsequently modify it to exclude certain paths.

Guidelines for Using XMLIndex with an Unstructured Component
The following are some guidelines for using XMLIndex with an unstructured
component. These guidelines are applicable only when the two alternatives discussed
return the same result set.
■

■

■

Avoid prefixing // with ancestor elements. For example, use //c, not /a/b//c,
provided these return the same result set.
Avoid prefixing /* with ancestor elements. For example, use /*/*/*, not
/a/*/*, provided these return the same result set.
In a WHERE clause, use XMLExists rather than XMLCast of XMLQuery. This can
allow optimization that, in effect, invokes a subquery against the path-table VALUE
column. For example, use this:
SELECT count(*) FROM purchaseorder p
WHERE
XMLExists('$p/PurchaseOrder/LineItems/LineItem/Part[@Id="715515011020"]'
PASSING OBJECT_VALUE AS "p");

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XMLIndex

Do not use this:
SELECT count(*) FROM purchaseorder p
WHERE XMLCast(XMLQuery('$p/PurchaseOrder/LineItems/LineItem/Part/@Id'
PASSING OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(14))
= "715515011020";
■

When possible, use count(*), not count(XMLCast(XMLQuery(...)), in a
SELECT clause. For example, if you know that a LineItem element in a
purchase-order document has only one Description child, use this:
SELECT count(*) FROM po_clob, XMLTable('//LineItem' PASSING OBJECT_VALUE);

Do not use this:
SELECT count(li.value)
FROM po_clob p, XMLTable('//LineItem' PASSING p.OBJECT_VALUE
COLUMNS value VARCHAR2(30) PATH 'Description') li;
■

Reduce the number of XPath expressions used in a query FROM list as much as
possible. For example, use this:
SELECT li.description
FROM po_clob p,
XMLTable('PurchaseOrder/LineItems/LineItem' PASSING p.OBJECT_VALUE
COLUMNS description VARCHAR2(256) PATH 'Description') li;

Do not use this:
SELECT li.description
FROM po_clob p,
XMLTable('PurchaseOrder/LineItems' PASSING p.OBJECT_VALUE) ls,
XMLTable('LineItems/LineItem'
PASSING ls.OBJECT_VALUE
COLUMNS description VARCHAR2(256) PATH 'Description') li;
■

If you use an XPath expression in a query to drill down inside a virtual table
(created, for example, using SQL/XML function XMLTable), then create a
secondary index on the order key of the path table using Oracle SQL function
sys_orderkey_depth. Here is an example of such a query; the selection
navigates to element Description inside virtual line-item table li.
SELECT li.description
FROM po_clob p,
XMLTable('PurchaseOrder/LineItems/LineItem' PASSING p.OBJECT_VALUE
COLUMNS description VARCHAR2(256) PATH 'Description') li;

Such queries are evaluated using function sys_orderkey_depth, which returns
the depth of the order-key value. Because the order index uses two columns, the
index needed is a composite index over columns ORDER_KEY and RID, as well as
over function sys_orderkey_depth applied to the ORDER_KEY value. For
example:
CREATE INDEX depth_ix ON my_path_table
(RID, sys_orderkey_depth(ORDER_KEY), ORDER_KEY);

See Also: Example 6–27 on page 6-27 for an example that shows the
use of sys_orderkey_depth

Indexing XMLType Data

6-33

XMLIndex

Guidelines for Using XMLIndex with a Structured Component
The following are some guidelines for using XMLIndex with a structured component.
■

■

■

■

Use XMLIndex with a structured component to project and index XML data as
relational columns. Do not use function-based indexes; they are deprecated for use
with XML. See "Function-Based Indexes" on page 6-5.
Ensure data type correspondence between a query and an XMLIndex index that
has a structured component. See "Data Type Considerations for XMLIndex
Structured Component" on page 6-11.
If you create a relational view over XMLType data (for example, using SQL
function XMLTable), then you consider also creating an XMLIndex index with a
structured component that targets the same relational columns. See Chapter 19,
"XMLType Views".
Instead of using a single XQuery expression for both fragment extraction and
value filtering (search), use SQL/XML function XMLQuery in the SELECT clause
to extract fragments and XMLExists in the WHERE clause to filter values.
This lets Oracle XML DB evaluate fragment extraction functionally or by using
streaming evaluation. For value filtering, this lets Oracle XML DB pick up an
XMLIndex index that has a relevant structured component.

■

To order query results, use a SQL ORDER BY clause, together with SQL/XML
function XMLTable. Avoid using the XQuery order by clause. This is
particularly pertinent if you use an XMLIndex index with a structured component.

XMLIndex Partitioning and Parallelism
If you partition an XMLType table, or a table with an XMLType column using range or
list partitioning, you can also create an XMLIndex index on the table. If you use the
keyword LOCAL when you create the XMLIndex index, then the index and all of its
storage tables are locally equipartitioned with respect to the base table.
If you do not use the keyword LOCAL, then you cannot create an XMLIndex index on a
partitioned table. Also, if you hash-partition a table, then you cannot create an
XMLIndex index on it.
You can use a PARALLEL clause (with optional degree) when creating or altering an
XMLIndex index to ensure that index creation and maintenance are carried out in
parallel. If the base table is partitioned or enabled for parallelism, then this can
improve the performance for both DML operations (INSERT, UPDATE, DELETE) and
index DDL operations (CREATE, ALTER, REBUILD).
Specifying parallelism for an index can also consume more storage, because storage
parameters apply separately to each query server process. For example, an index
created with an INITIAL value of 5M and a parallelism degree of 12 consumes at least
60M of storage during index creation.
The syntax for the parallelism clause for CREATE INDEX and ALTER INDEX is the
same as for other domain indexes:
{ NOPARALLEL | PARALLEL [ integer ] }

Example 6–34 creates an XMLIndex index with a parallelism degree of 10. If the base
table is partitioned, then this index is equipartitioned.
Example 6–34

Creating an XMLIndex Index in Parallel

CREATE INDEX po_xmlindex_ix ON sale_info (sale_po_clob) INDEXTYPE IS XDB.XMLIndex

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XMLIndex

LOCAL PARALLEL 10;

In Example 6–34, the path table and the secondary indexes are created with the same
parallelism degree as the XMLIndex index itself, 10, by inheritance. You can specify
different parallelism degrees for these by using separate PARALLEL clauses.
Example 6–35 demonstrates this. Again, because of keyword LOCAL, if the base table is
partitioned, then this index is equipartitioned.
Example 6–35

Using Different PARALLEL Degrees for XMLIndex Internal Objects

CREATE INDEX po_xmlindex_ix ON sale_info (sale_po_clob) INDEXTYPE IS XDB.XMLIndex
LOCAL PARAMETERS ('PATH TABLE po_path_table (PARALLEL 10)
PIKEY INDEX po_pikey_ix
VALUE INDEX po_value_ix (PARALLEL 5)') NOPARALLEL;

In Example 6–35, the XMLIndex index itself is created serially, because of
NOPARALLEL. The secondary index po_pikey_ix is also populated serially, because
no parallelism is specified explicitly for it; it inherits the parallelism of the XMLIndex
index. The path table itself is created with a parallelism degree of 10, and the
secondary index value column, po_value_ix, is populated with a degree of 5, due to
their explicit parallelism specifications.
Any parallelism you specify for an XMLIndex index, its path table, or its secondary
indexes is exploited during subsequent DML operations and queries.
Note that there are two places where you can specify parallelism for XMLIndex:
within the PARAMETERS clause parenthetical expression and after it.
See Also:
■

■

■

Oracle Database SQL Language Reference for information on the
CREATE INDEX parallel clause
"PARAMETERS Clause for CREATE INDEX and ALTER INDEX"
on page 6-38 for the syntax of the PARAMETERS clause
"Structured and Unstructured XMLIndex Components" on
page 6-9

Asynchronous (Deferred) Maintenance of XMLIndex Indexes
This feature applies to an XMLIndex index that has only an unstructured component. If
you specify asynchronous maintenance for an XMLIndex index that has a structured
component, then an error is raised.
By default, XMLIndex indexing is updated (maintained) at each DML operation, so
that it remains in sync with the base table. In some situations, you might not require
this, and using possibly stale indexes might be acceptable. In that use case, you can
decide to defer the cost of index maintenance, performing at commit time only or at
some time when database load is reduced. This can improve DML performance. It can
also improve index maintenance performance by enabling bulk loading of
unsynchronized index rows when an index is synchronized.
Using a stale index has no effect, other than performance, on DML operations. It can
have an effect on query results, however: If the index is not up-to-date at query time,
then the query results might not be up-to-date either. Even if only one column of a
base table is of data type XMLType, all queries on that table reflect the database data as
of the last synchronization of the XMLIndex index on the XMLType column.
You can specify index maintenance deferment using the parameters clause of a
CREATE INDEX or ALTER INDEX statement.
Indexing XMLType Data

6-35

XMLIndex

Be aware that even if you defer synchronization for an XMLIndex index, the following
database operations automatically synchronize the index:
■

■

Any DDL operation on the index – ALTER INDEX or creation of secondary
indexes
Any DDL operation on the base table – ALTER TABLE or creation of another index

Table 6–7 lists the synchronization options and the ASYNC clause syntax you use to
specify them. The ASYNC clause is used in the PARAMETERS clause of a CREATE
INDEX or ALTER INDEX statement for XMLIndex.
Table 6–7

Index Synchronization

When to Synchronize ASYNC Clause Syntax
Always

ASYNC (SYNC ALWAYS)
This is the default behavior. You can specify it explicitly, to cancel a
previous ASYNC specification.

Upon commit

ASYNC (SYNC ON COMMIT)

Periodically

ASYNC (SYNC EVERY "repeat_interval")
repeat_interval is the same as for the calendaring syntax of
DBMS_SCHEDULER
To use EVERY, you must have the CREATE JOB privilege.

Manually, on demand

ASYNC (SYNC MANUAL)
You can manually synchronize the index using PL/SQL procedure
DBMS_XMLINDEX.SyncIndex.

Optional ASYNC syntax parameter STALE is intended for possible future use; you need
never specify it explicitly. It has value FALSE whenever ALWAYS is used; otherwise it
has value TRUE. Specifying an explicit STALE value that contradicts this rule raises an
error.
Example 6–36 creates an XMLIndex index that is synchronized every Monday at 3:00
pm, starting tomorrow.
Example 6–36

Specifying Deferred Synchronization for XMLIndex

CREATE INDEX po_xmlindex_ix ON po_clob (OBJECT_VALUE) INDEXTYPE IS XDB.XMLIndex
PARAMETERS ('ASYNC (SYNC EVERY "FREQ=HOURLY; INTERVAL = 1")');

Example 6–37 manually synchronizes the index created in Example 6–36.
Example 6–37

Manually Synchronizing an XMLIndex Index using SYNCINDEX

EXEC DBMS_XMLINDEX.SyncIndex('OE', 'PO_XMLINDEX_IX', REINDEX => TRUE);

When XMLIndex index synchronization is deferred, all DML changes (inserts,
updates, and deletions) made to the base table since the last index synchronization are
recorded in a pending table, one row per DML operation. The name of this table is the
value of column PEND_TABLE_NAME of static public views USER_XML_INDEXES,
ALL_XML_INDEXES, and DBA_XML_INDEXES.
You can examine this table to determine when synchronization might be appropriate
for a given XMLIndex index. The more rows there are in the pending table, the more
the index is likely to be in need of synchronization.

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XMLIndex

If the pending table is large, then setting parameter REINDEX to TRUE when calling
SyncIndex, as in Example 6–37, can improve performance. When REINDEX is TRUE,
all of the secondary indexes are dropped and then re-created after the pending table
data is bulk-loaded.
See Also:
■

■

Oracle Database PL/SQL Packages and Types Reference, section
"Calendaring Syntax", for the syntax of repeat_interval
Oracle Database PL/SQL Packages and Types Reference for
information on PL/SQL procedure DBMS_
XMLINDEX.SyncIndex

Collecting Statistics on XMLIndex Objects for the Cost-Based Optimizer
The Oracle Database cost-based optimizer determines how to most cost-effectively
evaluate a given query, including which indexes, if any, to use. For it to be able to do
this accurately, you must collect statistics on various database objects.
For XMLIndex, you normally need to collect statistics on only the base table on which
the XMLIndex index is defined (using, for example, procedure DBMS_
STATS.gather_table_stats). This automatically collects statistics for the
XMLIndex index itself, as well as the path table, its secondary indexes, and any
structured component content tables and their secondary indexes.
If you delete statistics on the base table (using procedure DBMS_STATS.delete_
table_stats), then statistics on the other objects are also deleted. Similarly, if you
collect statistics on the XMLIndex index (using procedure DBMS_STATS.gather_
index_stats), then statistics are also collected on the path table, its secondary
indexes, and any structured component content tables and their secondary indexes.
Example 6–38 collects statistics on the base table po_clob. Statistics are automatically
collected on the XMLIndex index, its path table, and the secondary path-table indexes.
Example 6–38

Automatic Collection of Statistics on XMLIndex Objects

CALL DBMS_STATS.gather_table_stats(USER, 'PO_CLOB', ESTIMATE_PERCENT => NULL);

See Also: "Data Dictionary Static Public Views Related to
XMLIndex" on page 6-37 for information about database views that
record statistics information for an XMLIndex index

Data Dictionary Static Public Views Related to XMLIndex
Information about the standard database indexes is available in static public views
USER_INDEXES, ALL_INDEXES, and DBA_INDEXES. Similar information about
XMLIndex indexes is available in static public views USER_XML_INDEXES, ALL_XML_
INDEXES, and DBA_XML_INDEXES.
Table 6–8 describes the columns in each of these views.

Table 6–8

XMLIndex Static Public Views

Column Name

Type

Description

ASYNC

VARCHAR2 Asynchronous index updating specification. See
"Asynchronous (Deferred) Maintenance of XMLIndex
Indexes" on page 6-35.

Indexing XMLType Data

6-37

XMLIndex

Table 6–8 (Cont.) XMLIndex Static Public Views
Column Name

Type

Description

EX_OR_INCLUDE

VARCHAR2 Path subsetting:
■

FULLY_IX – The index uses no path subsetting.

■

EXCLUDE – The index uses only exclusion subsetting.

■

INCLUDE – The index uses only inclusion subsetting.

INDEX_NAME

VARCHAR2 Name of the XMLIndex index.

INDEX_OWNER

VARCHAR2 Owner of the index. Not available for USER_XML_INDEXES.

INDEX_TYPE

VARCHAR2 The types of components the index is composed of:
STRUCTURED, UNSTRUCTURED, or STRUCTURED AND
UNSTRUCTURED.

PARAMETERS

XMLType

Information from the PARAMETERS clause that was used to
create the index.
If an unstructured XMLIndex component is present, the
PARAMETERS clause can include the set of XPath paths
defining path-subsetting and the name of a scheduler job for
synchronization.
If a structured component is present, the PARAMETERS
clause includes the name of the structure group and the
table definitions provided by XMLTable, including the
XQuery expressions that define the columns.

PATH_TABLE_NAME VARCHAR2 Name of the XMLIndex path table.
PEND_TABLE_NAME VARCHAR2 Name of the table that records base-table DML operations
since the last index synchronization. See "Asynchronous
(Deferred) Maintenance of XMLIndex Indexes" on
page 6-35.
TABLE_NAME

VARCHAR2 Name of the base table on which the index is defined.

TABLE_OWNER

VARCHAR2 Owner of the base table on which the index is defined.

These views provide information about an XMLIndex index, but there is no single
catalog view that provides information about the statistics gathered for an XMLIndex
index. This statistics information is distributed among the following views:
■

■

■

USER_INDEXES, ALL_INDEXES, DBA_INDEXES – Column LAST_ANALYZED
provides the date when the XMLIndex index was last analyzed.
USER_TAB_STATISTICS, ALL_TAB_STATISTICS, DBA_TAB_STATISTICS –
Column TABLE_NAME provides information about the structured and
unstructured components of an XMLIndex index. For information about the
structured or unstructured component, query using the name of the path table or
the XMLTable table as TABLE_NAME, respectively.
USER_IND_STATISTICS, ALL_IND_STATISTICS, DBA_IND_STATISTICS –
Column INDEX_NAME provides information about each of the secondary indexes
for an XMLIndex index. for information about a given secondary index, query
using the name of that secondary index as INDEX_NAME.

PARAMETERS Clause for CREATE INDEX and ALTER INDEX
This section describes the usage and syntax of the PARAMETERS clause for SQL
statements CREATE INDEX and ALTER INDEX when used with XMLIndex.

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See Also:
■

■

■

■

■

■

■

Oracle Database SQL Language Reference for the syntax of index_
attributes
Oracle Database SQL Language Reference for the syntax of
segment_attributes_clause
Oracle Database SQL Language Reference for the syntax of table_
properties
Oracle Database SQL Language Reference for the syntax of
parallel_clause
Oracle Database SQL Language Reference for additional information
about the syntax and semantics of CREATE INDEX
Oracle Database SQL Language Reference for additional information
about the syntax and semantics of ALTER INDEX
Oracle Database PL/SQL Packages and Types Reference, section
"Calendaring Syntax", for the syntax of repeat_interval

Using a Registered PARAMETERS Clause for XMLIndex
The string value used for the PARAMETERS clause of a CREATE INDEX or ALTER
INDEX statement has a 1000-character limit. To get around this limitation, you can use
PL/SQL procedures registerParameter and modifyParameter in package
DBMS_XMLINDEX.
For each of these procedures, you provide a string of parameters (unlimited in length)
and an identifier under which the string is registered. Then, in the index PARAMETERS
clause, you provide the identifier preceded by the keyword PARAM, instead of a literal
string.
The identifier must already have been registered before you can use it in a CREATE
INDEX or ALTER INDEX statement.

PARAMETERS Clause Syntax for CREATE INDEX and ALTER INDEX
XMLIndex_parameters_clause ::=
XMLIndex_parameters
PARAMETERS

(

’

’
PARAM

See Also:

)

identifier

"Usage of XMLIndex_parameters_clause" on page 6-44

XMLIndex_parameters ::=
XMLIndex_parameter_clause

See Also:

"Usage of XMLIndex_parameters" on page 6-44

Indexing XMLType Data

6-39

XMLIndex

XMLIndex_parameter_clause ::=
unstructured_clause
structured_clause
async_clause

unstructured_clause ::=
create_index_paths_clause
PATHS
alter_index_paths_clause
path_table_clause
pikey_clause
parallel_clause

path_id_clause
order_key_clause
value_clause
drop_path_table_clause

create_index_paths_clause ::=
INCLUDE

(

XPaths_list

namespace_mapping_clause

)

(

)
EXCLUDE

(

XPaths_list

)

See Also:
■
■

"Usage of PATHS Clause" on page 6-44
"Usage of create_index_paths_clause and alter_index_paths_
clause" on page 6-44

alter_index_paths_clause ::=
INDEX_ALL_PATHS
(

namespace_mapping_clause

INCLUDE

ADD

EXCLUDE

REMOVE

(

XPaths_list

)

)

See Also:
■
■

"Usage of PATHS Clause" on page 6-44
"Usage of create_index_paths_clause and alter_index_paths_
clause" on page 6-44

namespace_mapping_clause ::=
NAMESPACE

MAPPING

6-40 Oracle XML DB Developer's Guide

(

namespace

)

XMLIndex

path_table_clause ::=
identifier
PATH

(

segment_attributes_clause

table_properties

)

TABLE

pikey_clause ::=
identifier

(

index_attributes

)

INDEX
PIKEY

See Also: "Usage of pikey_clause, path_id_clause, and order_key_
clause" on page 6-45

path_id_clause ::=
identifier

(

index_attributes

)

INDEX
PATH

ID

See Also: "Usage of pikey_clause, path_id_clause, and order_key_
clause" on page 6-45

order_key_clause ::=
identifier

(

index_attributes

)

INDEX
ORDER

KEY

See Also: "Usage of pikey_clause, path_id_clause, and order_key_
clause" on page 6-45

value_clause ::=
identifier

(

index_attributes

)

INDEX
VALUE

"Usage of value_clause" on page 6-45

See Also:

drop_path_table_clause ::=
DROP

PATH

TABLE

parallel_clause ::=
NOPARALLEL
integer
PARALLEL

Indexing XMLType Data

6-41

XMLIndex

structured_clause ::=
groups_clause
alter_index_group_clause

See Also: "Usage of groups_clause and alter_index_group_clause"
on page 6-45

async_clause ::=
FALSE

ALWAYS

STALE

(

)
TRUE

MANUAL
ASYNC

(

SYNC

)
EVERY
ON

repeat_interval
COMMIT

See Also:

"Usage of async_clause" on page 6-45

groups_clause ::=
group_clause

See Also: "Usage of groups_clause and alter_index_group_clause"
on page 6-45

group_clause ::=
GROUP

identifier
XMLIndex_xmltable_clause

See Also: "Usage of groups_clause and alter_index_group_clause"
on page 6-45

XMLIndex_xmltable_clause ::=
(
XMLTABLE

segment_attributes_clause

table_properties

)

identifier

XML_namespaces_clause

,
XQuery_string

PASSING

,

identifier
COLUMNS

column_clause

Syntax elements XML_namespaces_clause and XQuery_string are the same as for SQL/XML
function XMLTable.

6-42 Oracle XML DB Developer's Guide

XMLIndex

See Also:
■

"Usage of XMLIndex_xmltable_clause" on page 6-45

■

"XMLTABLE SQL/XML Function in Oracle XML DB" on page 5-7

column_clause ::=
FOR

ORDINALITY

column

VIRTUAL
datatype

PATH

string

Syntax element column_clause is similar, but not identical, to XML_table_column in
SQL/XML function XMLTable.
See Also:
■

"Usage of column_clause" on page 6-46

■

"XMLTABLE SQL/XML Function in Oracle XML DB" on page 5-7

alter_index_group_clause ::=
ADD_GROUP

groups_clause
,
GROUP

identifier

DROP_GROUP
add_column_clause
drop_column_clause

See Also: "Usage of groups_clause and alter_index_group_clause"
on page 6-45

add_column_clause :==
ADD_COLUMN

add_column_options

add_column_options :==
GROUP

identifier

xml_namespaces_clause
XMLTABLE

identifier

,

,
COLUMNS

column_clause

Syntax element XML_namespaces_clause is the same as for SQL/XML function
XMLTable. See "XMLTABLE SQL/XML Function in Oracle XML DB" on page 5-7.
drop_column_clause :==
DROP_COLUMN

drop_column_options

Indexing XMLType Data

6-43

XMLIndex

drop_column_options :==
GROUP

,

identifier
XMLTABLE

identifier

COLUMNS

identifier

Usage of XMLIndex_parameters_clause
When you create an XMLIndex index, if there is no XMLIndex_parameters_
clause, then the new index has only an unstructured component. If there is an
XMLIndex_parameters_clause, but the PARAMETERS argument is empty (''),
then the result is the same: an index with only an unstructured component.

Usage of XMLIndex_parameters
The following considerations apply to using XMLIndex_parameters.
■

■

There can be at most one XMLIndex_parameter_clause of each type in
XMLIndex_parameters. For example, there can be at most one PATHS clause, at
most one path_table_clause, and so on.
If there is no structured_clause when you create an XMLIndex index, then
the new index has only an unstructured component. If there is only a
structured_clause, then the new index has only a structured component.

Usage of PATHS Clause
The following considerations apply to using the PATHS clause.
■

■

There can be at most one PATHS clause in a CREATE INDEX statement. That is,
there can be at most one occurrence of PATHS followed by create_index_
paths_clause.
Clause create_index_paths_clause is used only with CREATE INDEX;
alter_index_paths_clause is used only with ALTER INDEX.

Usage of create_index_paths_clause and alter_index_paths_clause
The following considerations apply to using create_index_paths_clause and
alter_index_paths_clause.
■

■
■

■

■

■

The INDEX_ALL_PATHS keyword rebuilds the index to include all paths. This
keyword is available only for alter_index_paths_clause, not create_
index_paths_clause.
An explicit list of paths to index can include wildcards and //.
XPaths_list is a list of one or more XPath expressions, each of which includes
only child axis, descendant axis, name test, and wildcard (*) constructs.
If XPaths_list is omitted from create_index_paths_clause, all paths are
indexed.
For each unique namespace prefix that is used in an XPath expression in XPaths_
list, a standard XML namespace declaration is needed, to provide the
corresponding namespace information.
You can change an index in ways that are not reflected directly in the syntax by
dropping it and then creating it again as needed. For example, to change an index
that was defined by including paths to one that is defined by excluding paths,
drop it and then create it using EXCLUDE.

6-44 Oracle XML DB Developer's Guide

XMLIndex

Usage of pikey_clause, path_id_clause, and order_key_clause
Syntactically, each of the clauses pikey_clause, path_id_clause, and order_
key_clause is optional. A pikey index is created even if you do not specify a pikey_
clause. To create a path id index or an order-key index, you must specify a path_
id_clause or an order_key_clause, respectively.

Usage of value_clause
The following considerations apply to using value_clause.
■
■

■

■

Column VALUE is created as VARCHAR2(4000).
If clause value_clause consists only of the keyword VALUE, then the value
index is created with the usual default attributes.
If clause path_id_clause consists only of the keywords PATH ID, then the
path-id index is created with the usual default attributes.
If clause order_key_clause consists only of the keywords ORDER KEY, then the
order-key index is created with the usual default attributes.

Usage of async_clause
The following considerations apply to using the ASYNC clause.
■

■
■

■

■

■

Use this feature only with an XMLIndex index that has only an unstructured
component. If you specify an ASYNC clause for an XMLIndex index that has a
structured component, then an error is raised.
ALWAYS means automatic synchronization occurs for each DML statement.
MANUAL means no automatic synchronization occurs. You must manually
synchronize the index using DBMS_XMLINDEX.SyncIndex.
EVERY repeat_interval means automatically synchronize the index at interval
repeat_interval. The syntax of repeat_interval is the same as that for
PL/SQL package DBMS_SCHEDULER, and it must be enclosed in double-quotes
("). To use EVERY you must have the CREATE JOB privilege.
ON COMMIT means synchronize the index immediately after a commit operation.
The commit does not return until the synchronization is complete. Since the
synchronization is performed as a separate transaction, there can be a short period
when the data is committed but index changes are not yet committed.
STALE is optional. A value of TRUE means that query results might be stale; a
value of FALSE means that query results are always up-to-date. The default value,
and the only permitted explicitly specified value, is as follows.
–

For ALWAYS, STALE is TRUE.

–

For any other ASYNC option besides ALWAYS, STALE is FALSE.

Usage of groups_clause and alter_index_group_clause
Clause groups_clause is used only with CREATE INDEX; clause alter_index_
group_clause is used only with ALTER INDEX.

Usage of XMLIndex_xmltable_clause
The following considerations apply to using XMLIndex_xmltable_clause.
■

The XQuery_string expression in XMLIndex_xmltable_clause must not use
the XQuery functions ora:view (deprecated), fn:doc, or fn:collection.

Indexing XMLType Data

6-45

Oracle Text Indexes on XML Data

■

■

Oracle XML DB raises an error if a given XMLIndex_xmltable_clause contains
more than one column_clause of data type XMLType. To achieve the effect of
defining two such virtual columns, you must instead add a separate group_
clause.
The PASSING clause in XMLIndex_xmltable_clause is optional. If not present,
then an XMLType column is passed implicitly, as follows:
–

For the first XMLIndex_xmltable_clause in a parameters clause, the
XMLType column being indexed is passed implicitly. (When indexing an
XMLType table, pseudocolumn OBJECT_VALUE is passed.)

–

For each subsequent XMLIndex_xmltable_clause, the VIRTUAL XMLType
column of the preceding XMLIndex_xmltable_clause is passed implicitly.

Usage of column_clause
When you use multilevel chaining of XMLTable in an XMLIndex index, the
XMLTable table at one level corresponds to an XMLType column at the previous level.
The syntax description shows keyword VIRTUAL as optional. In fact, it is used only for
such an XMLType column, in which case it is required. It is an error to use it for a
non-XMLType column. VIRTUAL specifies that the XMLType column itself is not
materialized, meaning that its data is stored in the index only in the form of the
relational columns specified by its corresponding XMLTable table.

Oracle Text Indexes on XML Data
You can create an Oracle Text index on an XMLType column. An Oracle Text CONTEXT
index enables Oracle SQL function contains for full-text search over XML. With
structured storage, XPath rewrite can often rewrite XPath function ora:contains to
SQL function contains, so in those cases too an Oracle Text index can be employed.
See Also:
■

■

Chapter 12, "Full-Text Search Over XML Data" for more
information about using Oracle Text operations with Oracle
XML DB
Example 6–23, "Oracle Text CONTEXT Index on an XMLIndex
Index Content Table" on page 6-24

Creating and Using Oracle Text Indexes
To create an Oracle Text index, use CREATE INDEX, specifying the INDEXTYPE as
CTXSYS.CONTEXT, as illustrated in Example 6–39.
Example 6–39

Creating an Oracle Text Index

CREATE INDEX po_otext_ix ON po_clob (OBJECT_VALUE) INDEXTYPE IS CTXSYS.CONTEXT;

You can also perform Oracle Text operations such as contains and score on
XMLType columns. Example 6–40 shows an Oracle Text search using Oracle SQL
function contains.
Example 6–40

Searching XML Data using SQL Function CONTAINS

SELECT DISTINCT XMLCast(XMLQuery('$p/PurchaseOrder/ShippingInstructions/address'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(256)) "Address"
FROM po_clob po
6-46 Oracle XML DB Developer's Guide

Oracle Text Indexes on XML Data

WHERE contains(po.OBJECT_VALUE,
'$(Fortieth) INPATH (PurchaseOrder/ShippingInstructions/address)') > 0;
Address
-----------------------------1200 East Forty Seventh Avenue
New York
NY
10024
USA
1 row selected.

The execution plan for this query shows two ways that the Oracle Text CONTEXT index
is used:
■

It references the index explicitly, as a domain index.

■

It refers to Oracle SQL function contains in the predicate information.

PLAN_TABLE_OUTPUT
-------------------------------------------------------------------------------------------Plan hash value: 274475732
-------------------------------------------------------------------------------------------| Id | Operation
| Name
| Rows | Bytes | Cost (%CPU)| Time
|
-------------------------------------------------------------------------------------------|
0 | SELECT STATEMENT
|
|
7 | 14098 |
10 (10)| 00:00:01 |
|
1 | HASH UNIQUE
|
|
7 | 14098 |
10 (10)| 00:00:01 |
|
2 |
TABLE ACCESS BY INDEX ROWID| PO_CLOB
|
7 | 14098 |
9
(0)| 00:00:01 |
|* 3 |
DOMAIN INDEX
| PO_OTEXT_IX |
|
|
4
(0)| 00:00:01 |
-------------------------------------------------------------------------------------------Predicate Information (identified by operation id):
--------------------------------------------------3 - access("CTXSYS"."CONTAINS"(SYS_MAKEXML('2B0A2483AB140B35E040578C8A173FEC',523
3,"XMLDATA"),'$(Fortieth) INPATH (PurchaseOrder/ShippingInstructions/address)')>0)
20 rows selected.

Oracle Text Indexes Are Used Independently of Other Indexes
Oracle Text indexing is completely orthogonal to the other types of indexing described
in this chapter. Whenever Oracle SQL function contains or XPath function
ora:contains is used, an Oracle Text index can be used for full-text search.
Example 6–41 demonstrates this in the case where both an XMLIndex index and an
Oracle Text index are defined on the same XML data. The query is the same as in
Example 6–40. The Oracle Text index is created on the VALUE column of the XMLIndex
path table of Example 6–9.
Example 6–41

Using an Oracle Text Index and an XMLIndex Index

CREATE INDEX po_otext_ix ON my_path_table (VALUE) INDEXTYPE IS CTXSYS.CONTEXT;
EXPLAIN PLAN FOR
SELECT DISTINCT XMLCast(XMLQuery('$p/PurchaseOrder/ShippingInstructions/address'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(256)) "Address"
FROM po_clob po
WHERE contains(po.OBJECT_VALUE,

Indexing XMLType Data

6-47

Oracle Text Indexes on XML Data

'$(Fortieth) INPATH (PurchaseOrder/ShippingInstructions/address)') > 0;
------------------------------------------------------------------------------------------------------------| Id | Operation
| Name
| Rows | Bytes | Cost (%CPU)| Time
|
------------------------------------------------------------------------------------------------------------|
0 | SELECT STATEMENT
|
|
7 | 14098 |
3 (34)| 00:00:01 |
|
1 | SORT GROUP BY
|
|
1 | 3524 |
|
|
|* 2 |
TABLE ACCESS BY INDEX ROWID| MY_PATH_TABLE
|
2 | 7048 |
3
(0)| 00:00:01 |
|* 3 |
INDEX RANGE SCAN
| SYS67616_PO_XMLINDE_PIKEY_IX |
1 |
|
2
(0)| 00:00:01 |
|
4 | HASH UNIQUE
|
|
7 | 14098 |
3 (34)| 00:00:01 |
|* 5 |
TABLE ACCESS FULL
| PO_CLOB
|
7 | 14098 |
2
(0)| 00:00:01 |
------------------------------------------------------------------------------------------------------------Predicate Information (identified by operation id):
--------------------------------------------------2 - filter(SYS_XMLI_LOC_ISNODE("SYS_P0"."LOCATOR")=1)
3 - access("SYS_P0"."RID"=:B1 AND "SYS_P0"."PATHID"=HEXTORAW('6F7F') )
5 - filter("CTXSYS"."CONTAINS"(SYS_MAKEXML(0,"SYS_ALIAS_1"."XMLDATA"),'$(Fortieth) INPATH
(PurchaseOrder/ShippingInstructions/address)')>0)
Note
----- dynamic sampling used for this statement (level=2)
- Unoptimized XML construct detected (enable XMLOptimizationCheck for more information)
24 rows selected.

The execution plan in Example 6–41 references both the XMLIndex index and the
Oracle Text index, indicating that both are used.
■

■

The XMLIndex index is indicated by its path table, MY_PATH_TABLE, and its
order-key index, SYS78942_PO_XMLINDE_ORDKEY_IX.
The Oracle Text index is indicated by the reference to Oracle SQL function
contains in the predicate information.

6-48 Oracle XML DB Developer's Guide

7
XML Schema Storage and Query: Basic
The XML Schema Recommendation was created by the World Wide Web Consortium
(W3C) to describe the content and structure of XML documents in XML. It includes the
full capabilities of Document Type Definitions (DTDs) so that existing DTDs can be
converted to XML Schema. XML schemas have additional capabilities compared to
DTDs.
This chapter provides basic information about using XML Schema with Oracle
XML DB. It explains how to do the following:
■

Register, update, and delete an XML schema

■

Create storage structures for XML schema-based data

■

Map XML Schema data types to SQL data types

This chapter contains these topics:
■

Overview of XML Schema and Oracle XML DB

■

Using Oracle XML DB with XML Schema

■

Managing XML Schemas with DBMS_XMLSCHEMA

■

XMLType Methods Related to XML Schema

■

Local and Global XML Schemas

■

DOM Fidelity

■

XML Translations

■

Creating XMLType Tables and Columns Based on XML Schemas

■

Oracle XML Schema Annotations

■

Querying a Registered XML Schema to Obtain Annotations

■

Mapping XML Schema Data Types to Oracle XML DB Storage

■

Mapping XML Schema Data Types to SQL Data Types

XML Schema Storage and Query: Basic 7-1

Overview of XML Schema and Oracle XML DB

See Also:
■

■

■

Chapter 9, "XML Schema Storage and Query: Advanced" for
more advanced information about using XML Schema with
Oracle XML DB
Chapter 8, "XPath Rewrite for Structured Storage" for
information about the optimization of XPath expressions in
Oracle XML DB
http://www.w3.org/TR/xmlschema-0/ for an
introduction to XML Schema

Overview of XML Schema and Oracle XML DB
XML Schema is a schema definition language written in XML. It can be used to
describe the structure and semantics of conforming instance documents. For example,
the following XML schema definition, purchaseOrder.xsd, describes the structure
and other properties of purchase-order XML documents.
This manual refers to an XML schema instance definition as an XML schema.
Example 7–1 shows an XML schema that declares a complexType called
purchaseOrderType and a global element PurchaseOrder of this type. This is the
same schema as Example 3–9, "Purchase-Order XML Schema, purchaseOrder.xsd",
with the exception of the lines in bold here, which are additional. For brevity, part of
the schema is replaced here by an ellipsis (...).
Example 7–1 XML Schema Instance purchaseOrder.xsd





















...

7-2 Oracle XML DB Developer's Guide

Overview of XML Schema and Oracle XML DB















Example 7–2 shows an XML document that conforms to XML schema
purchaseOrder.xsd:
Example 7–2 purchaseOrder.xml: Document That Conforms to purchaseOrder.xsd

SBELL-2002100912333601PDT


SVOLLMAN



Sarah J. Bell
SBELL
S30

Sarah J. Bell
400 Oracle Parkway
Redwood Shores
CA
94065
USA

650 506 7400

Air Mail


A Night to Remember



The Unbearable Lightness Of Being



Sisters



Section 1.10.32 of "de Finibus Bonorum et Malorum",

XML Schema Storage and Query: Basic 7-3

Overview of XML Schema and Oracle XML DB

written by Cicero in 45 BC
"Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium
doloremque laudantium, totam rem aperiam, eaque ips
...
tiae consequatur, vel illum qui dolorem eum fugiat quo voluptas nulla
pariatur?"
1914 translation by H. Rackham
"But I must explain to you how all this mistaken idea of denouncing
pleasure and praising pain was born and I will give you a c
...
o avoids a pain that produces no resultant pleasure?"
Section 1.10.33 of "de Finibus Bonorum et Malorum", written by Cicero
in 45 BC
"At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis
praesentium voluptatum deleniti atque corrupti quos
...
delectus, ut aut reiciendis voluptatibus maiores alias
consequatur aut perferendis doloribus asperiores repellat."
1914 translation by H. Rackham
"On the other hand, we denounce with righteous indignation and dislike men
who are so beguiled and demoralized by the charms of
...
secure other greater pleasures, or else he endures pains to avoid worse
pains."



The URL used is a name that uniquely identifies the
registered XML schema within the database:
http://xmlns.oracle.com/xdb/documentation/purchase
Order.xsd. This need not point to a location where the XML
schema document is located. The target namespace of the XML
schema is another URL, different from the XML schema location
URL, which specifies an abstract namespace within which elements
and types get declared.

Note:

An XML schema can optionally specify the target namespace URL.
If this attribute is omitted, the XML schema has no target
namespace. The target namespace is commonly the same as the
URL of the XML schema.
An XML instance document must specify the namespace of the root
element (same as the target namespace of the XML schema) and the
location (URL) of the XML schema that defines this root element.
The location is specified with attribute xsi:schemaLocation.
When the XML schema has no target namespace, use attribute
xsi:noNamespaceSchemaLocation to specify the schema URL.

7-4 Oracle XML DB Developer's Guide

Using Oracle XML DB with XML Schema

Using Oracle XML DB with XML Schema
Oracle XML DB exploits the strong typing and other powerful properties of XML
Schema to process XML database data safely and efficiently.
With XML data that is stored using binary XML storage, you
can use a DTD to obtain the XML entities defined there. However, the
structural and type information in the DTD is not used by Oracle
XML DB. The entities are the only information used.

Note:

Oracle XML DB uses annotated XML schemas as metadata. The standard XML Schema
definitions are used, along with several Oracle namespace attributes. These attributes
determine how XML instance documents get mapped to the database. Because these
attributes are in a different namespace from the XML Schema namespace, such
annotated XML schemas are legal XML Schema documents.
See Also:

http://www.w3.org/2001/XMLSchema

When using Oracle XML DB with XML Schema, you must first register the XML
schema. You can then use the XML schema URLs while creating XMLType tables,
columns, and views. The XML schema URL identifies the XML schema in the
database. It is associated with parameter SCHEMAURL of PL/SQL procedure DBMS_
XMLSCHEMA.registerSchema.
Oracle XML DB provides XML Schema support for the following tasks:
■

Registering W3C-compliant XML schemas, both local and global.

■

Validating your XML documents against registered XML schema definitions.

■

Generating XML schemas from SQL object types.

■

Referencing an XML schema owned by another user.

■

■

■

Explicitly referencing a global XML schema when a local XML schema exists with
the same name.
Generating a database mapping from your XML schemas during XML schema
registration. This includes generating SQL object types, collection types, and
default tables, and capturing the mapping information using XML schema
attributes.
Specifying a particular SQL data type mapping when there are multiple allowed
mappings.

■

Creating XMLType tables, views, and columns based on registered XML schemas.

■

Manipulating and querying XML schema-based XMLType tables.

■

Automatically inserting data into default tables when XML schema-based
documents are inserted into Oracle XML DB Repository using protocols (FTP,
HTTP(S)/WebDAV) and languages besides SQL.
See Also:

Chapter 3, "Using Oracle XML DB"

Why XML Schema?
XMLType is an abstract data type that facilitates storing XML data in database columns
and tables. XML Schema offers you additional storage and access options for XML

XML Schema Storage and Query: Basic 7-5

Managing XML Schemas with DBMS_XMLSCHEMA

data. You can use XML schemas to define which XML elements and attributes, which
kinds of element nesting, and which data types can be used.
XML Schema lets you verify that your XML data conforms to its intended definition:
the data is validated against the XML schemas that define its proper structure. This
definition includes data types, numbers of allowed item occurrences, and allowed
lengths of items. When storing XML Schema-based documents in Oracle XML DB
using protocols such as FTP or HTTP(S), the XML schema information can improve
the efficiency of document insertion. When XML instances must be handled without
any prior information about them, XML schemas can be useful in predicting optimum
storage, fidelity, and access.
You can take advantage of XML Schema, including its strong typing, for XML data
that is unstructured, semi-structured, or structured by storing it as binary XML.
If your XML data is highly structured, then consider storing it object-relationally. In
that case, XML Schema is used to efficiently map XML (Schema) data types to SQL
data types and object-relational tables and columns.

DTD Support in Oracle XML DB
A DTD is a set of rules that define the allowable structure of an XML document. DTDs
are text files that derive their format from SGML and can be associated with an XML
document either by using the DOCTYPE element or by using an external file through a
DOCTYPE reference. In addition to supporting XML Schema, which provides a
structured mapping to object-relational storage or binary XML storage, Oracle
XML DB also supports DTD specifications in XML instance documents. Though DTDs
are not used to derive the mapping, XML processors can still access and interpret the
DTDs.

Inline DTD Definitions
When an XML instance document has an inline DTD definition, it is used during
document parsing. Any DTD validations and entity declaration handling is done at
this point. However, once parsed, the entity references are replaced with actual values
and the original entity reference is lost.

External DTD Definitions
Oracle XML DB also supports external DTD definitions if they are stored in Oracle
XML DB Repository. Applications needing to process an XML document containing an
external DTD definition such as /public/flights.dtd must first ensure that the
DTD document is stored in Oracle XML DB at path /public/flights.dtd.
See Also: Chapter 21, "Accessing Oracle XML DB Repository
Data"

Managing XML Schemas with DBMS_XMLSCHEMA
Before an XML schema can be used by Oracle XML DB, it must be registered with
Oracle Database. You register an XML schema using the PL/SQL package DBMS_
XMLSCHEMA.
See Also:

Oracle Database PL/SQL Packages and Types Reference

Some of the main DBMS_XMLSCHEMA procedures are these:
■

registerSchema – Register an XML schema with Oracle Database

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Managing XML Schemas with DBMS_XMLSCHEMA

■
■

deleteSchema – Delete a previously registered XML schema.
copyEvolve – Update a registered XML schema. See Chapter 10, "XML Schema
Evolution".

Registering an XML Schema with Oracle XML DB
The main parameters to procedure DBMS_XMLSCHEMA.registerSchema are these:
■

SCHEMAURL – the XML schema URL. This is a unique identifier for the XML
schema within Oracle XML DB. It is conventionally in the form of a URL, but this
is not a requirement. The XML schema URL is used with Oracle XML DB to
identify instance documents, by making the schema location hint identical to the
XML schema URL. Oracle XML DB never tries to access a Web server identified by
the specified URL.

You cannot register an XML schema using the same
SCHEMAURL as any system-defined XML schema.

Note:

■

■

■

SCHEMADOC – The XML schema source document. This is a VARCHAR, CLOB, BLOB,
BFILE, XMLType, or URIType value.
CSID – The character-set ID of the source-document encoding, when schemaDoc
is a BFILE or BLOB value.
OPTIONS – Options that specify how the XML schema should be registered. The
most important option is REGISTER_BINARYXML, which indicates that the XML
schema is used for binary XML storage. Another option is REGISTER_NT_AS_
IOT, which forces OCTs to be stored as index-organized tables (IOTs).

If you specify option REGISTER_BINARYXML, then you must
also set parameter GENTYPES to FALSE.

Note:

See Also:

Oracle Database PL/SQL Packages and Types Reference

The code in Example 7–3 registers the XML schema at URL
http://xmlns.oracle.com/xdb/documentation/purchaseOrder.xsd. This
example shows how to register an XML schema using the BFILE mechanism to read
the source document from a file on the local file system of the database server.
Example 7–3 Registering an XML Schema using DBMS_
XMLSCHEMA.REGISTERSCHEMA
BEGIN
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'http://xmlns.oracle.com/xdb/documentation/purchaseOrder.xsd',
SCHEMADOC => bfilename('XMLDIR','purchaseOrder.xsd'),
CSID
=> nls_charset_id('AL32UTF8'));
END;
/

XML Schema Storage and Query: Basic 7-7

Managing XML Schemas with DBMS_XMLSCHEMA

Delete and Reload Documents Before Registering Their XML Schema
When you register an XML schema, keep in mind that the act of registering a schema
has no effect on the status of any instance documents already loaded into Oracle
XML DB Repository that reference the XML schema. Because the XML schema was not
yet registered, such instance documents were non-schema-based when they were
loaded. They remain non-schema-based after the schema is registered.
You must delete such instance documents, and reload them after registering the schema,
in order to obtain schema-based documents.

Storage and Access Infrastructure
As part of registering an XML schema, Oracle XML DB also performs several tasks
that facilitate storing, accessing, and manipulating XML instances that conform to the
XML schema. These steps include:
■

■

Mapping XML Schema data types to Oracle XML DB storage. When XML
schema-based data is stored, its storage data types are derived from the XML
Schema data types using a default mapping and, optionally, using mapping
information that you specify using XML schema annotations. For binary XML
storage, XML Schema types are mapped to binary XML encoding types. For
object-relational storage, XML schema registration creates the appropriate SQL
object types for the structured storage of conforming documents.
Creating default tables. XML schema registration generates default XMLType
tables for all global elements. You can use XML-schema annotations to control the
names of the tables, and to provide column-level and table-level storage clauses
and constraints for use during table creation.
See Also:
■

■

■

"Mapping XML Schema Data Types to Oracle XML DB Storage"
on page 7-44
"Default Tables Created During XML Schema Registration" on
page 7-10
"Oracle XML Schema Annotations" on page 7-34

After XML schema registration, documents that reference the XML schema using the
XML Schema instance mechanism can be processed automatically by Oracle XML DB.
For XML data that is stored object-relationally, XMLType tables and columns can be
created that are constrained to the global elements defined by the XML schema.
See Also:

Chapter 3, "Using Oracle XML DB"

Atomic Nature of XML Schema Registration
Like all DDL operations, XML schema registration is non-transactional. However,
registration is atomic, in this sense:
■
■

If registration succeeds, then the operation is auto-committed.
If registration fails, then the database is rolled back to the state before registration
began.

Because XML schema registration potentially involves creating object types and tables,
error recovery involves dropping any types and tables thus created. The entire XML
schema registration process is guaranteed to be atomic: either it succeeds or the
database is restored to its state before the start of registration.
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Managing XML Schemas with DBMS_XMLSCHEMA

Managing and Storing XML Schemas
XML schema documents are themselves stored in Oracle XML DB as XMLType
instances. XML schema-related XMLType types and tables are created as part of the
Oracle XML DB installation script, catxdbs.sql.
The XML schema for Oracle XML DB XML schemas is called the root XML Schema,
XDBSchema.xsd. The root XML schema describes any valid XML schema that can be
registered with Oracle XML DB. You can access XDBSchema.xsd at Oracle XML DB
Repository location
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/XDBSchema.xsd.
See Also:

Chapter 34, "Administering Oracle XML DB"

Debugging XML Schema Registration for XML Data Stored Object-Relationally
For XML data stored object-relationally, you can monitor the object types and tables
created during XML schema registration by setting the following event before
invoking PL/SQL procedure DBMS_XMLSCHEMA.registerSchema:
ALTER SESSION SET EVENTS = '31098 TRACE NAME CONTEXT FOREVER'

Setting this event causes the generation of a log of all of the CREATE TYPE and
CREATE TABLE statements. This log is written to the user session trace file, typically
found in ORACLE_BASE/diag/rdbms/ORACLE_SID/ORACLE_SID/udump. This
script can be a useful aid in diagnosing problems during XML schema registration.
See Also:

"Using XML Schema with Oracle XML DB" on

page 3-18

SQL Object Types Created During XML Schema Registration, for Structured Storage
If parameter GENTYPES is TRUE when an XML schema is registered for use with XML
data stored object-relationally, then Oracle XML DB creates the appropriate SQL object
types that enable structured storage of conforming XML documents. By default, all
SQL object types are created in the database schema of the user who registers the XML
schema. If annotation xdb:defaultSchema is used, then Oracle XML DB attempts to
create the object type using the specified database schema. The current user must have
the necessary privileges to create these object types.
Example 7–4 shows the SQL object types that are created automatically when XML
schema purchaseOrder.xsd is registered with Oracle XML DB.
Example 7–4 Creating SQL Object Types to Store XMLType Tables
DESCRIBE "PurchaseOrderType1668_T"
"PurchaseOrderType1668_T" is NOT FINAL
Name
Null? Type
-------------------- ------ ------------------------------SYS_XDBPD$
XDB.XDB$RAW_LIST_T
Reference
VARCHAR2(30 CHAR)
Actions
ActionsType1661_T
Reject
RejectionType1660_T
Requestor
VARCHAR2(128 CHAR)
User
VARCHAR2(10 CHAR)
CostCenter
VARCHAR2(4 CHAR)
ShippingInstructions
ShippingInstructionsTyp1659_T
SpecialInstructions
VARCHAR2(2048 CHAR)
LineItems
LineItemsType1666_T

XML Schema Storage and Query: Basic 7-9

Managing XML Schemas with DBMS_XMLSCHEMA

Notes

VARCHAR2(4000 CHAR)

DESCRIBE "LineItemsType1666_T"
"LineItemsType1666_T" is NOT FINAL
Name
Null? Type
-------------------- ----- ------------------------------SYS_XDBPD$
XDB.XDB$RAW_LIST_T
LineItem
LineItem1667_COLL
DESCRIBE "LineItem1667_COLL"
"LineItem1667_COLL" VARRAY(2147483647) OF LineItemType1665_T
"LineItemType1665_T" is NOT FINAL
Name
Null? Type
------------------- ----- -------------------------------SYS_XDBPD$
XDB.XDB$RAW_LIST_T
ItemNumber
NUMBER(38)
Description
VARCHAR2(256 CHAR)
Part
PartType1664_T

By default, the names of the SQL object types and attributes
are system-generated. This is the case in Example 7–4. If the XML
schema does not contain attribute SQLName, then the SQL name is
derived from the XML name. You can use XML schema annotations
to provide user-defined names (see "Oracle XML Schema
Annotations" for details).

Note:

Default Tables Created During XML Schema Registration
As part of XML schema registration for XML data, you can create default tables.
Default tables are most useful when documents conforming to the XML schema are
inserted through APIs and protocols such as FTP and HTTP(S) that do not provide any
table specification. In such cases, the XML instance is inserted into the default table.
Example 7–5 Default Table for Global Element PurchaseOrder
DESCRIBE "purchaseorder1669_tab"
Name
Null? Type
--------------------------- ----- ----------------------TABLE of
SYS.XMLTYPE(
XMLSchema "http://xmlns.oracle.com/xdb/documentation/purchaseOrder.xsd"
Element "PurchaseOrder")
STORAGE OBJECT-RELATIONAL TYPE "PurchaseOrderType1668_T"

If you provide a value for attribute xdb:defaultTable, then the XMLType table is
created with that name. Otherwise it is created with an internally generated name.
Any text specified using attributes xdb:tableProps and xdb:columnProps is
appended to the generated CREATE TABLE statement.

Do Not Use Internal Constructs Generated during XML Schema Registration
In general, the SQL constructs generated during XML schema registration are internal
to Oracle XML DB. Oracle recommends that you do not use them in your code.
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Managing XML Schemas with DBMS_XMLSCHEMA

More precisely, generated SQL data types, nested tables, and tables associated with
out-of-line storage are all internal. They are based on specific XML schema-to-object
type mappings that are subject to change and redefinition by Oracle at any time.
In general:
■

Do not use any generated SQL data types.

■

Do not access or modify any generated nested tables or out-of-line tables.

You can, however, modify the storage options, such as partitioning, of generated
tables, and you can create indexes and constraints on generated tables. You can also
freely use any XML schema annotations provided by Oracle XML DB, including to
name generated constructs for your convenience.

Generated Names are Case Sensitive
The names of any SQL tables, object, and attributes generated by XML schema
registration are case sensitive. For instance, in Example 7–3 on page 7-7, a table named
PurchaseOrder1669_TAB is created automatically during registration of the XML
schema. Because this table name was derived from the element name,
PurchaseOrder, the table name is also mixed case. You must therefore refer to this
table in SQL code by using a quoted identifier: "PurchaseOrder1669_TAB". Failure
to do so results in an object-not-found error, such as ORA-00942: table or view
does not exist.

Database Objects That Depend on Registered XML Schemas
The following database objects are dependent on registered XML schemas:
■

■

■

Tables or views that have an XMLType column that conforms to an element in an
XML schema.
Other XML schemas that include or import a given XML schema as part of their
definition.
Cursors that reference an XML schema. This includes references within functions
of package DBMS_XMLGEN. Such cursors are purely transient objects.

Listing All Registered XML Schemas
Example 7–6 shows how to use PL/SQL procedure DBMS_
XMLSCHEMA.registerSchema to obtain a list of all XML schemas registered with
Oracle XML DB. You can also examine views USER_XML_SCHEMAS, ALL_XML_
SCHEMAS, USER_XML_TABLES, and ALL_XML_TABLES.
Example 7–6 Data Dictionary Table for Registered Schemas
DESCRIBE DBA_XML_SCHEMAS
Name
Null? Type
------------ ----- ----------------------OWNER
VARCHAR2(30)
SCHEMA_URL
VARCHAR2(700)
LOCAL
VARCHAR2(3)
SCHEMA
XMLTYPE(XMLSchema "http://xmlns.oracle.com/xdb/XDBSchema.xsd"
Element "schema")
INT_OBJNAME
VARCHAR2(4000)
QUAL_SCHEMA_URL
VARCHAR2(767)
HIER_TYPE
VARCHAR2(11)

XML Schema Storage and Query: Basic

7-11

Managing XML Schemas with DBMS_XMLSCHEMA

BINARY
SCHEMA_ID
HIDDEN

VARCHAR2(3)
RAW(16)
VARCHAR2(3)

SELECT OWNER, LOCAL, SCHEMA_URL FROM DBA_XML_SCHEMAS;
OWNER
----XDB
XDB
XDB
XDB
XDB
XDB
XDB
XDB
XDB
XDB
XDB
XDB
SCOTT

LOC
--NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
YES

SCHEMA_URL
---------------------http://xmlns.oracle.com/xdb/XDBSchema.xsd
http://xmlns.oracle.com/xdb/XDBResource.xsd
http://xmlns.oracle.com/xdb/acl.xsd
http://xmlns.oracle.com/xdb/dav.xsd
http://xmlns.oracle.com/xdb/XDBStandard.xsd
http://xmlns.oracle.com/xdb/log/xdblog.xsd
http://xmlns.oracle.com/xdb/log/ftplog.xsd
http://xmlns.oracle.com/xdb/log/httplog.xsd
http://www.w3.org/2001/xml.xsd
http://xmlns.oracle.com/xdb/XDBFolderListing.xsd
http://xmlns.oracle.com/xdb/stats.xsd
http://xmlns.oracle.com/xdb/xdbconfig.xsd
http://xmlns.oracle.com/xdb/documentation/purchaseOrder.xsd

13 rows selected.
DESCRIBE DBA_XML_TABLES
Name
Null? Type
------------ ----- ----------------------OWNER
VARCHAR2(30)
TABLE_NAME
VARCHAR2(30)
XMLSCHEMA
VARCHAR2(700)
SCHEMA_OWNER
VARCHAR2(30)
ELEMENT_NAME
VARCHAR2(2000)
STORAGE_TYPE
VARCHAR2(17)
ANYSCHEMA
VARCHAR2(3)
NONSCHEMA
VARCHAR2(3)
SELECT TABLE_NAME FROM DBA_XML_TABLES
WHERE XMLSCHEMA = 'http://xmlns.oracle.com/xdb/documentation/purchaseOrder.xsd';
TABLE_NAME
--------------------PurchaseOrder1669_TAB
1 row selected.

Deleting an XML Schema
You can delete a registered XML schema by using procedure DBMS_
XMLSCHEMA.deleteSchema. This does the following, by default:
1.

Checks that the current user has the appropriate privileges to delete the resource
corresponding to the XML schema within Oracle XML DB Repository. You can
control which users can delete which XML schemas, by setting the appropriate
ACLs on the XML schema resources.

2.

Checks whether there are any tables dependent on the XML schema that is to be
deleted. If so, raises an error and cancels the deletion. This check is not performed
if option delete_invalidate or delete_cascade_force is used. In that
case, no error is raised.

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Managing XML Schemas with DBMS_XMLSCHEMA

3.

Removes the XML schema document from the Oracle XML DB Repository (folder
/sys/schemas).

4.

Removes the XML schema document from DBA_XML_SCHEMAS, unless it was
registered for use with binary XML instances and neither delete_invalidate
nor delete_cascade_force is used.

5.

Drops the default table, if either delete_cascade or delete_cascade_force
is used. Raises an error if delete_cascade_force is specified and there are
instances in other tables that are also dependent on the XML schema.

DBMS_XMLSCHEMA.DELETESCHEMA Options
The following values are available for option DELETE_OPTION of procedure DBMS_
XMLSCHEMA.deleteSchema:
■

■

■

■

DELETE_RESTRICT – Raise an error and cancel deletion if dependencies are
detected. This is the default behavior.
DELETE_INVALIDATE – Do not raise an error if dependencies are detected.
Instead, mark each of the dependencies as being invalid.
DELETE_CASCADE – Drop all types and default tables that were generated during
XML schema registration. Raise an error if there are instances that depend upon
the XML schema that are stored in tables other than the default table. However, do
not raise an error for any such instances that are stored in XMLType columns that
were created using ANY_SCHEMA. If the XML schema was registered for use with
binary XML, do not remove it from DBA_XML_SCHEMAS.
DELETE_CASCADE_FORCE – Drop all types and default tables that were generated
during XML schema registration. Do not raise an error if there are instances that
depend upon the XML schema that are stored in tables other than the default
table. Instead, mark each of the dependencies as being invalid. Remove the XML
schema from DBA_XML_SCHEMAS.
See Also:

Oracle Database PL/SQL Packages and Types Reference

Example 7–7 illustrates the use of DELETE_CASCADE_FORCE.
Example 7–7 Deleting an XML Schema with DBMS_XMLSCHEMA.DELETESCHEMA
BEGIN
DBMS_XMLSCHEMA.deleteSchema(
SCHEMAURL => 'http://xmlns.oracle.com/xdb/documentation/purchaseOrder.xsd',
DELETE_OPTION => DBMS_XMLSCHEMA.DELETE_CASCADE_FORCE);
END;
/

If an XML schema was registered for use with binary XML, it is not removed from
DBA_XML_SCHEMAS when you delete it using option DELETE_RESTRICT (the default
value) or DELETE_CASCADE. As a consequence, although you can no longer use the
XML schema to encode new XML instance documents, any existing documents in
Oracle XML DB that reference the XML schema can still be decoded using it.
This remains the case, until you remove the XML schema from DBA_XML_SCHEMAS
using DBMS_XMLSCHEMA.purgeSchema. Oracle recommends that, in general, you
use delete_restrict or delete_cascade. Instead of using DELETE_CASCADE_
FORCE, call DBMS_XMLSCHEMA.purgeSchema when you are sure you no longer need
the XML schema.

XML Schema Storage and Query: Basic

7-13

XMLType Methods Related to XML Schema

Procedure purgeSchema removes the XML schema completely from Oracle XML DB.
In particular, it removes it from DBA_XML_SCHEMAS. Before you use DBMS_
XMLSCHEMA.purgeSchema, be sure that you have transformed all existing XML
documents that reference the XML schema to be purged, so they reference a different
XML schema or no XML schema. Otherwise, it will be impossible to decode them after
the purge.

XMLType Methods Related to XML Schema
Table 7–1 lists some of the XMLType methods that are useful for working with XML
schemas.
Table 7–1

XMLType Methods Related to XML Schema

XMLType Method

Description

isSchemaBased()

Returns TRUE if the XMLType instance is based on an XML schema, FALSE
otherwise.

getSchemaURL()

The XML schema URL for an XMLType instance.

schemaValidate()
isSchemaValid()
isSchemaValidated()
setSchemaValidated()

Validate an XMLType instance against a registered XML schema.
See Chapter 11, "Transforming and Validating XMLType Data".

Local and Global XML Schemas
XML schemas can be registered as local or global:
■

A local xml schema is, by default, visible only to its owner.

■

A global xml schema is, by default, visible and usable by all database users.

When you register an XML schema, PL/SQL package DBMS_XMLSCHEMA adds a
corresponding resource to Oracle XML DB Repository. The XML schema URL
determines the path name of the XML schema resource in the repository (and it is
associated with parameter SCHEMAURL of PL/SQL procedure DBMS_
XMLSCHEMA.registerSchema).
In Oracle Enterprise Manager, local and global registered XML
schemas are referred to as private and public, respectively.

Note:

Local XML Schema
By default, an XML schema belongs to you after you register it with Oracle XML DB.
A reference to the XML schema document is stored in Oracle XML DB Repository.
Such XML schemas are referred to as local. By default, they are usable only by you, the
owner. In Oracle XML DB, local XML schema resources are created under folder
/sys/schemas/username. The rest of the repository path name is derived from the
schema URL.
Example 7–8 Registering a Local XML Schema
BEGIN
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'http://xmlns.oracle.com/xdb/documentation/purchaseOrder.xsd',
SCHEMADOC => bfilename('XMLDIR','purchaseOrder.xsd'),
LOCAL
=> TRUE,

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Local and Global XML Schemas

GENTYPES => TRUE,
GENTABLES => FALSE,
CSID
=> nls_charset_id('AL32UTF8'));
END;
/

If this local XML schema is registered by user QUINE, it is given this path name:
/sys/schemas/QUINE/xmlns.oracle.com/xdb/documentation/purchaseOrder.xsd

Database users need appropriate permissions and Access Control Lists (ACLs) to
create a resource with this path name, in order to register the XML schema as a local
XML schema.
See Also:

Chapter 27, "Repository Access Control"

Typically, only the owner of the XML schema can use it to
define XMLType tables, columns, or views, validate documents, and
so on. However, Oracle XML DB supports fully qualified XML
schema URLs. For example:
http://xmlns.oracle.com/xdb/schemas/QUINE/xmlns.or
acle.com/xdb/documentation/purchaseOrder.xsd.
Privileged users can use such an extended URL to specify XML
schemas belonging to other users.

Note:

Global XML Schema
In contrast to local schemas, a privileged user can register an XML schema as global by
specifying an argument in the DBMS_XMLSCHEMA registration function. Global XML
schemas are visible to all users. They are stored under folder
/sys/schemas/PUBLIC/ in Oracle XML DB Repository.
Access to folder /sys/schemas/PUBLIC is controlled by
access control lists (ACLs). By default, this folder is writable only
by a database administrator. You need write privileges on this
folder to register global XML schemas. Role XDBADMIN provides
write access to this folder, assuming that it is protected by the
default ACLs. See Chapter 27, "Repository Access Control".

Note:

You can register a local schema with the same URL as an existing global schema. A
local schema always shadows (hides) any global schema with the same name (URL).
Example 7–9 illustrates registration of a global schema.
Example 7–9 Registering a Global XML Schema
GRANT XDBADMIN TO QUINE;
Grant succeeded.
CONNECT quine
Enter password: password
Connected.
BEGIN

XML Schema Storage and Query: Basic

7-15

DOM Fidelity

DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'http://xmlns.oracle.com/xdb/documentation/purchaseOrder.xsd',
SCHEMADOC => bfilename('XMLDIR','purchaseOrder.xsd'),
LOCAL
=> FALSE,
GENTYPES => TRUE,
GENTABLES => FALSE,
CSID
=> nls_charset_id('AL32UTF8'));
END;
/

If this global XML schema is registered by user QUINE, it is given this path name:
/sys/schemas/PUBLIC/xmlns.oracle.com/xdb/documentation/purchaseOrder.xsd

Database users need appropriate permissions (ACL access) to create this resource in
order to register the XML schema as global.

DOM Fidelity
Document Object Model (DOM) fidelity is the concept of retaining the structure of a
retrieved XML document, compared to the original XML document, for DOM
traversals. DOM fidelity is needed to ensure the accuracy and integrity of XML
documents stored in Oracle XML DB.
See Also:
■

■

"Overriding the SQLType Value in an XML Schema When
Declaring Attributes" on page 7-47
"Overriding the SQLType Value in an XML Schema when
Declaring Elements" on page 7-48

What is DOM Fidelity?
DOM fidelity means that all information in an XML document is preserved, except
whitespace that is insignificant. With DOM fidelity, XML data retrieved from the
database has the same information as before it was inserted into the database, with the
single exception of insignificant whitespace. The term "DOM fidelity" is used because
this kind of fidelity is particularly important for DOM traversals.
With binary XML storage of XML data, all of the significant information is encoded in
the binary XML format, ensuring DOM fidelity. With structured storage of XML data,
the elements and attributes declared in an XML schema are mapped to separate
attributes in the corresponding SQL object types. However, the following information
in XML instance documents is not stored in these object attributes:
■

Namespace declarations

■

Comments

■

Prefix information

Instead, Oracle XML DB uses a separate mechanism to keep track of this information:
it is recorded as instance-level metadata.

SYS_XDBPD$ and DOM Fidelity for Structured Storage
In order to provide DOM fidelity for XML data stored object-relationally, Oracle
XML DB maintains instance-level metadata. This metadata is tracked at the type level
using the system-defined binary object attribute SYS_XDBPD$. This object attribute is

7-16 Oracle XML DB Developer's Guide

XML Translations

referred to as the positional descriptor, or PD for short. The PD is intended for Oracle
XML DB internal use only. You should never directly access or manipulate column PD.
The positional descriptor stores all information that cannot be stored in any of the
other object attributes. PD information is used to ensure the DOM fidelity of all XML
documents stored in Oracle XML DB. Examples of PD information include: ordering
information, comments, processing instructions, and namespace prefixes.
If DOM fidelity is not required, you can suppress the use of SYS_XDBPD$ by setting
attribute xdb:maintainDOM to false in the XML schema, at the type level.
Note: For clarity, object attribute SYS_XDBPD$ is omitted in many
examples in this book. However, it is always present as a positional
descriptor (PD) column in all SQL object types that are generated
by the XML schema registration process.

In general, Oracle recommends that you do not suppress the PD
attribute, because the extra information, such as comments and
processing instructions, could be lost if there is no PD column.

XML Translations
You can store XML documents in Oracle XML DB Repository as XMLType instances.
You can use any storage model for these instances: structured (object-relational
storage), unstructured (CLOB), or binary XML. These documents sometimes contain
strings that must be translated into various (natural) languages. You typically store
both the original strings and their translations in the repository. You can retrieve and
operate on these strings, depending on your language settings.
Note:

XML schemas stored object-relationally are not translatable.

Changing an XML Schema and XML Instance Documents for Translation
This section describes the changes that are required to be made to an XML schema and
an associated XML instance document to make the document translatable.

Indicating Translatable Elements in an XML Schema
Attribute xdb:translate must be specified in the XML schema for each element
that is to be translated. The following restrictions apply to attribute xdb:translate.
1.

Attribute xdb:translate can be specified only on complexType elements that
have simpleContent. Here, simpleContent must be an extension or a
restriction of type string. However, if a complexType element has the
xdb:translate flag set, then none of its descendants can have this flag set.

2.

Attribute xdb:translate can be set only on a single-valued element, which has
exactly one translation. For such an element, the value of maxoccurs must be 0 or
1. If you want to set this attribute on a multiple-valued element, the element must
have an ID attribute, which uniquely identifies the element.

During XML schema registration, PL/SQL procedure DBMS_
XMLSCHEMA.registerSchema checks whether the XML schema satisfies these
restrictions.

XML Schema Storage and Query: Basic

7-17

XML Translations

Indicating Translation Language Attributes in an XML Instance Document
The following translation language attributes are supported:
■

■

xml:lang: For an instance document associated with an XML schema that
supports translations, you must specify the translation language. You can do this
by annotating each translation with attribute xml:lang. The allowed values of
the xml:lang attribute are the language identifiers identified by IETF RFC 3066.
xdb:srclang: For multiple-valued elements, that is, elements that can have
multiple translations, only one translation can be used as the source language
translation. That translation is specified by attribute xdb:srclang. This is the
default translation, which is returned when the session language is not specified.

Making XML Documents Translatable
This section uses the translation-specifying XML schema attributes to make elements
in a sample document translatable. Example 7–10 shows an XML schema that defines
documents that contain a title string that needs to be translatable.
Example 7–10

XML Schema Defining Documents with a Title To Be Translated




This XML schema describes the structure of Security Class documents.






























7-18 Oracle XML DB Developer's Guide

XML Translations


































Example 7–11 shows a document that is associated with the XML schema of
Example 7–10.
Example 7–11

Untranslated Instance Document



securityClassExample


is:iStorePurchaseOrder








XML Schema Storage and Query: Basic

7-19

XML Translations










To make the top-level title translatable, set xdb:translate to true. This is a
single-valued element (xdb:maxOccurs is 1). Example 7–12 shows the new XML
schema, where attribute xdb:translate is true.
Example 7–12

XML Schema with Attribute xdb:translate for a Single-Valued Element






This XML schema describes the structure of Security Class documents.






























7-20 Oracle XML DB Developer's Guide

XML Translations













































Example 7–13 shows an instance document after translation of the title text.
Example 7–13

Translated Document



securityClassExample




is:iStorePurchaseOrder
















To make the title translatable in the case of a multi-valued element, you would set
xdb:maxOccurs to unbounded. However, xdb:translate cannot be set to true
for a multiple-valued element, unless there is an identifier attribute that uniquely
identifies each element. Example 7–14 shows an XML schema that uses an identifier
attribute id for the title element.
Example 7–14

XML Schema with Attribute xdb:translate for a Multi-Valued Element






This XML schema describes the structure of Security Class documents.















7-22 Oracle XML DB Developer's Guide

XML Translations

























































XML Schema Storage and Query: Basic

7-23

XML Translations






Example 7–15 shows a document associated with the XML schema in Example 7–14.
Example 7–15

Translated Document for an XML Schema with Multiple-Valued Elements



securityClassExample


is:iStorePurchaseOrder


















Operations on Translated Documents
You can perform the following operations on translated documents:
■

Insert: You can insert a document into Oracle XML DB, if it conforms to an XML
schema that supports translations. For the document that contains translations,
you can either provide the language information or use the session language
translation.
–

When the document does not contain the language information and the
xml:lang attribute is not set, the session language is used for translation.
Example 7–16 describes a document with a session language of Japanese.
Attribute xml:lang is set to session language, and attribute
xdb:srclang is set to true.

7-24 Oracle XML DB Developer's Guide

XML Translations

Example 7–16

Inserting a Document with No Language Information



securityClassExample


is:iStorePurchaseOrder


Example 7–17 shows the document after it is inserted into Oracle XML DB
Repository.
Example 7–17

Document After Insertion into the Repository



securityClassExample


is:iStorePurchaseOrder


–

When you provide the language information, you set attribute xml:lang by
either explicitly marking a translation as xdb:srclang=true or using the
session language translation in attribute xdb:srclang. If you do neither,
then an arbitrary translation is picked, for which xdb:srclang is set to true.
Example 7–18 describes a document with a session language of Japanese.

Example 7–18

Inserting a Document with Language Information



securityClassExample



is:iStorePurchaseOrder


XML Schema Storage and Query: Basic

7-25

XML Translations

Example 7–19 shows the document after it is inserted into Oracle XML DB
Repository.
Example 7–19

Document After Insertion



securityClassExample



is:iStorePurchaseOrder

■

Query: If you query nodes that involve translated elements, the query displays the
translation's default behavior. In order to specify that the translation's default
behavior should be applied to the query result, you need to use the Oracle XPath
function ora:translate. This is the syntax of the function:
Nodeset ora:translate(Nodeset parent, String childname, String childnsp)

Parameter parent is the parent node under which you want to search for the
translated nodes; childname is the name of the child node; and childnsp is the
namespace URL of the child node.
Function ora:translate returns a positive integer when the name of the parent
node matches the name of the specified child node, and the xml:lang value is
same as the session language or the language for which xdb:srclang is true.
When SQL functions such as XMLQuery are applied to translated documents, they
return the session language translation, if present, or the source language
translation, otherwise. For example, this query returns the session language
translation:
SELECT XMLQuery('$x/ora:translate(securityClass, "title")'
PASSING x.OBJECT_VALUE AS "x" RETURNING CONTENT)
FROM some_table x;

This is the output of that query:


To obtain the result in a particular language, specify it in the XPath expression.
SELECT XMLQuery('$x/securityClass/title[@xml:lang="en"]'
PASSING x.OBJECT_VALUE AS "x" RETURNING CONTENT)
FROM some_table x;

This is the output of that query:


7-26 Oracle XML DB Developer's Guide

Creating XMLType Tables and Columns Based on XML Schemas

Because you can store translated documents only as text (CLOB) or binary XML,
only functional evaluation and queries with a function-based index, an XMLIndex
index, or a CONTEXT index are possible. For XMLIndex index and CONTEXT index
queries, if the document has a session language translation, then that is returned,
otherwise the source language translation is returned. However, for queries with a
function-based index, you need to create an index with an explicit xml:lang
predicate for every language for which you want to use the index.
When you retrieve the complete document using SQL functions such as
XMLSerialize and XDBURIType, only the translations that match the session
language translations are returned. For protocols, you can set your language
preferences, and the document is returned in that language only.
The following PL/SQL procedures and functions support XML translations:
■

DBMS_XMLTRANSLATIONS.translateXML: Translate a document to the
specified language. If the specified language translation is present, it is
returned, otherwise, the source language translation is returned.
For example, if you write translateXML(doc, 'fr') to specify French as
the translation language for the Example 7–19, it returns the following code
and ignores all other translations:
securityClass xmlns="http://xmlns.oracle.com/xdb/security.xsd"
xmlns:is="xmlns.oracle.com/iStore"
xmlns:oa="xmlns.oracle.com/OracleApps"
targetNamespace="xmlns.oracle.com/example">

securityClassExample


is:iStorePurchaseOrder


■

■

■

DBMS_XMLTRANSLATIONS.enableTranslation, DBMS_
XMLTRANSLATIONS.disableTranslation: Enable or disable translations
at the session level. Queries work on the base document if the translation is
disabled and on the translated document if it is enabled.
DBMS_XMLTRANSLATIONS.getBaseDocument: Returns the entire
document, with all of the translations.

Update: You can use Oracle SQL function updateXML to update the translated
nodes. However, an error is raised if you try to update a translated node without
specifying the translation language. The following PL/SQL procedures support
update operations on translated documents:
■

■

DBMS_XMLTRANSLATIONS.updateTranslation: This function updates the
translation at a specified xpath in a particular language. If the translation in a
particular language is not present, then it is inserted.
DBMS_XMLTRANSLATIONS.setSourceLang: This procedure sets the source
language at a specified xpath to the specified language.

Creating XMLType Tables and Columns Based on XML Schemas
Using Oracle XML DB, you can create XMLType tables and columns that are
constrained to a global element defined by a registered XML schema. After an
XML Schema Storage and Query: Basic

7-27

Creating XMLType Tables and Columns Based on XML Schemas

XMLType column has been constrained to a particular element and a particular XML
schema, it can only contain documents that are compliant with the schema definition
of that element. You constrain an XMLType table column to a particular element and
XML schema by adding appropriate XMLSCHEMA and ELEMENT clauses to the CREATE
TABLE operation.
Figure 7–1 through Figure 7–4 show the syntax for creating an XMLType table.
See Also: Oracle Database SQL Language Reference for the complete
description of CREATE TABLE, including syntax elements such as
object_properties.

To create an XMLType table in a different database schema
from your own, you must have not only privilege CREATE ANY
TABLE but also privilege CREATE ANY INDEX. This is because a
unique index is created on column OBJECT_ID when you create the
table. Column OBJECT_ID stores a system-generated object identifier.

Note:

Figure 7–1 Creating an XMLType Table – CREATE TABLE
GLOBAL

relational_table

TEMPORARY

CREATE

TABLE

schema

.

table

object_table
XMLType_table

Figure 7–2 Creating an XMLType Table – XMLType_table
(
OF

oject_properties

)

XMLTYPE

XMLType_storage

XMLSchema_spec

XMLTYPE

DELETE
ON

COMMIT

ROWS

XMLType_virtual_columns

OID_clause

PRESERVE

OID_index_clause

physical_properties

table_properties

Figure 7–3 Creating an XMLType Table – table_properties
CACHE
column_properties

table_partitioning_clauses

NOCACHE

DEFAULT
RESULT_CACHE

(

MODE

ROWDEPENDENCIES
)

FORCE

enable_disable_clause

row_movement_clause

7-28 Oracle XML DB Developer's Guide

parallel_clause

flashback_archive_clause

NOROWDEPENDENCIES

AS

subquery

Creating XMLType Tables and Columns Based on XML Schemas

Figure 7–4 Creating an XMLType Table – XMLType_virtual_columns
,
VIRTUAL

COLUMNS

(

column

AS

(

expr

)

)

For XML data, virtual columns are used primarily for
partitioning or defining SQL constraints. If your need is to project out
specific XML data in order to access it relationally, then consider using
SQL/XML function XMLTable or XMLIndex with a structured
component. See also:

Note:

■

"Partitioning or Constraining Binary XML Data using Virtual
Columns" on page 3-3

■

"XMLTABLE SQL/XML Function in Oracle XML DB" on page 5-7

■

"XMLIndex Structured Component" on page 6-10

A subset of the XPointer notation can also be used to provide a single URL that
contains the XML schema location and element name. See also Chapter 4, "XMLType
Operations".
Example 7–20 shows two CREATE TABLE statements. The first creates XMLType table
purchaseorder_as_table. The second creates relational table purchaseorder_
as_column, which has XMLType column xml_document. In each table, the XMLType
instance is constrained to the PurchaseOrder element that is defined by the XML
schema registered with URL
http://xmlns.oracle.com/xdb/documentation/purchaseOrder.xsd.
Example 7–20

Creating XML Schema-Based XMLType Tables and Columns

CREATE TABLE purchaseorder_as_table OF XMLType
XMLSCHEMA "http://xmlns.oracle.com/xdb/documentation/purchaseOrder.xsd"
ELEMENT "PurchaseOrder";
CREATE TABLE purchaseorder_as_column (id NUMBER, xml_document XMLType)
XMLTYPE COLUMN xml_document
ELEMENT
"http://xmlns.oracle.com/xdb/documentation/purchaseOrder.xsd#PurchaseOrder";

There are two ways to specify XMLSchema and Element:
■

as separate clauses, XMLSchema and Element

■

using only the Element clause with an XPointer notation

The data associated with an XMLType table or column that is constrained to an XML
schema can be stored in different ways:
■

Decomposed and stored object-relationally (structured storage)

■

Stored as text, using a single CLOB column (unstructured storage)

■

Stored as binary XML, using a single binary-XML column (binary XML storage)

Specifying XMLType Storage Options for XML Schema-Based Data
You can specify storage options to use when you manually create a table that stores
XML instance documents that reference an XML schema. To specify a particular

XML Schema Storage and Query: Basic

7-29

Creating XMLType Tables and Columns Based on XML Schemas

XMLType storage model, use a STORE AS clause in the CREATE TABLE statement.
Otherwise, the storage model specified during registration of the XML schema is used.
If no storage model was specified during registration, then object-relational storage is
used.
This section describes what you need to know about specifying storage options for
XML schema-based data. You can also specify storage options for tables that are
created automatically, by using XML schema annotations.
See Also:

"Oracle XML Schema Annotations" on page 7-34

Binary XML Storage of XML Schema-Based Data
If you specify STORE AS BINARY_XML, then binary XML storage is used. If you
specify an XML schema that the XML documents must conform to, then you can use
that XML schema only to create XMLType tables and columns that are stored as binary
XML. You cannot use the same XML schema to create XMLType tables and columns
that are stored object-relationally or as CLOB instances.
The converse is also true: If you use a storage model other than binary XML for the
registered XML schema, then you can use only that XML schema to create XMLType
tables and columns that are not stored object-relationally or as CLOB instances.
Binary XML storage offers a great deal of flexibility for XML data, especially
concerning the use of XML schemas. Binary XML encodes XML data differently,
depending upon whether or not an XML schema is used for the encoding, and it can
encode the same data differently using different XML schemas.
When an XML schema is taken into account for encoding binary XML data, the XML
Schema data types are mapped to encoded types for storage. Alternatively, you can
encode XML data as non-schema-based binary XML, whether or not the data
references an XML schema. In that case, any referenced XML schema is ignored, and
there is no encoding of XML Schema data types.
When you create an XMLType table or column and you use binary XML storage, you
can specify how to encode the column or table to make use of XML schemas. Choose
from among these possibilities:
■

Encode the column or table data as non-schema-based binary XML. The XML data
stored in the column can nevertheless conform to an XML schema, but it need not.
Any referenced XML schema is ignored for encoding purposes, and documents
are not automatically validated when they are inserted or updated.
You can nevertheless explicitly validate an XML schema-based document that is
encoded as non-schema-based binary XML. This represents an important use case:
situations where you do not want to tie documents too closely to a particular XML
schema, because you might change it or delete it.

■

■

Encode the column or table data to conform to a single XML schema. All rows
(documents) must conform to the same XML schema. You can nevertheless
specify, as an option, that non-schema-based documents can also be stored in the
same column.
Encode the column or table data to conform to whatever XML schema it references
Each row (document) can reference any XML schema, and that XML schema is used
to encode that particular XML document. In this case also, you can specify, as an
option, that non-schema-based documents can also be stored in the same column.
You can use multiple versions of the same XML schema in this way. Store
documents that conform to different versions. Each is encoded according to the
XML schema that it references.

7-30 Oracle XML DB Developer's Guide

Creating XMLType Tables and Columns Based on XML Schemas

You can specify that any XML schema can be used for encoding by using option
ALLOW ANYSCHEMA when you create the table.
Note:
■

■

If you use option ALLOW ANYSCHEMA, then any XML schema
referenced by your instance documents is used only for validation.
It is not used at query time. Queries of your data treat it as if it
were non XML schema-based data.
Oracle recommends that you do not use option ALLOW
ANYSCHEMA if you anticipate using copy-based XML schema
evolution (see "Using Copy-Based Schema Evolution" on
page 10-2). If you use this option, it is impossible to determine
which rows (documents) might conform to the XML schema that
is evolved. Conforming rows are not transformed during
copy-based evolution, and afterward they are not decodable.

You can specify, for tables and columns that use XML schema-based encodings, that
they can accept also non-schema-based documents by using option ALLOW
NONSCHEMA. In the absence of keyword XMLSCHEMA, encoding is for
non-schema-based documents. In the absence of the keywords ALLOW NONSCHEMA
but the presence of keyword XMLSCHEMA, encoding is for the single XML schema
specified. In the absence of the keywords ALLOW NONSCHEMA but the presence of the
keywords ALLOW ANYSCHEMA, encoding is for any XML schema that is referenced.
An error is raised if you try to insert an XML document into an XMLType table or
column that does not correspond to the document.
The various possibilities are summarized in Table 7–2.
Table 7–2

CREATE TABLE Encoding Options for Binary XML

Storage Options

Encoding Effect

STORE AS BINARY XML Encodes all documents using the non-schema-based encoding.
STORE AS BINARY XML Encodes all documents using an encoding based on the referenced
XML schema.
XMLSCHEMA ...
Trying to insert or update a document that does not conform to the
XML schema raises an error.
STORE AS BINARY XML Encodes all XML schema-based documents using an encoding based
on the referenced XML schema. Encodes all non-schema-based
XMLSCHEMA ...
documents using the non-schema-based encoding.
ALLOW NONSCHEMA
Trying to insert or update an XML schema-based document that does
not conform to the referenced XML schema raises an error.
STORE AS BINARY XML Encodes all XML schema-based documents using an encoding based
on the XML schema referenced by the document.
ALLOW ANYSCHEMA
Trying to insert or update a document that does not reference a
registered XML schema or that does not conform to the XML schema it
references raises an error.
STORE AS BINARY XML Encodes all XML schema-based documents using an encoding based
on the XML schema referenced by the document. Encodes all
ALLOW ANYSCHEMA
non-schema-based documents using the non-schema-based encoding.
ALLOW NONSCHEMA
Trying to insert or update an XML schema-based document that does
not conform to the registered XML schema it references raises an error.

XML Schema Storage and Query: Basic

7-31

Creating XMLType Tables and Columns Based on XML Schemas

If you use CREATE TABLE with ALLOW NONSCHEMA but not
ALLOW ANYSCHEMA, then all documents, even XML schema-based
documents, are encoded using the non-schema-based encoding. If you
later use ALTER TABLE with ALLOW ANYSCHEMA on the same table,
this has no effect on the encoding of documents that were stored prior
to the ALTER TABLE operation—all such documents continue to be
encoded using the non-schema-based encoding, regardless of whether
they reference an XML schema. Only XML schema-based documents
that you insert in the table after the ALTER TABLE operation are
encoded using XML schema-based encodings.

Note:

Unstructured Storage of XML Schema-Based Data
You use STORE AS CLOB during table creation to specify unstructured storage. In this
case, an entire XML document is stored in a single CLOB column.
Example 7–21 shows how to create an XMLType table and a table with an XMLType
column, where the contents of the XMLType are constrained to a global element
defined by a registered XML schema, and the contents of the XMLType are stored
using a single CLOB column.
Example 7–21
Columns

Specifying CLOB Storage for Schema-Based XMLType Tables and

CREATE TABLE purchaseorder_as_table OF XMLType
XMLTYPE STORE AS CLOB
XMLSCHEMA "http://xmlns.oracle.com/xdb/documentation/purchaseOrder.xsd"
ELEMENT "PurchaseOrder";
CREATE TABLE purchaseorder_as_column (id NUMBER, xml_document XMLType)
XMLTYPE COLUMN xml_document
STORE AS CLOB
XMLSCHEMA "http://xmlns.oracle.com/xdb/documentation/purchaseOrder.xsd"
ELEMENT "PurchaseOrder";

You can add LOB storage parameters to the STORE AS CLOB clause.

Structured Storage of XML Schema-Based Data
With structured storage, collections are mapped into SQL varray values. An XML
collection is any element that has maxOccurs > 1, allowing it to appear multiple
times. By default, the entire contents of such a varray is stored as a set of rows in an
ordered collection table (OCT).
Example 7–22 illustrates specifying additional storage options. The LineItem
collection varray is stored as a LOB, not as a table. USERS is the tablespace used for
storing element Notes. The table is compressed for online transaction processing
(OLTP).
Example 7–22

Specifying Structured Storage Options for XMLType Tables and Columns

CREATE TABLE purchaseorder_as_table
OF XMLType (UNIQUE ("XMLDATA"."Reference"),
FOREIGN KEY ("XMLDATA"."User") REFERENCES hr.employees (email))
ELEMENT
"http://xmlns.oracle.com/xdb/documentation/purchaseOrder.xsd#PurchaseOrder"
VARRAY "XMLDATA"."LineItems"."LineItem" STORE AS LOB lineitem_lob
LOB ("XMLDATA"."Notes")

7-32 Oracle XML DB Developer's Guide

Creating XMLType Tables and Columns Based on XML Schemas

STORE AS (TABLESPACE USERS ENABLE STORAGE IN ROW
STORAGE(INITIAL 4K NEXT 32K))
COMPRESS FOR OLTP;
CREATE TABLE purchaseorder_as_column (
id NUMBER,
xml_document XMLType,
UNIQUE (xml_document."XMLDATA"."Reference"),
FOREIGN KEY (xml_document."XMLDATA"."User") REFERENCES hr.employees (email))
XMLTYPE COLUMN xml_document
XMLSCHEMA "http://xmlns.oracle.com/xdb/documentation/purchaseOrder.xsd"
ELEMENT "PurchaseOrder"
VARRAY xml_document."XMLDATA"."LineItems"."LineItem" STORE AS LOB lineitem_lob
LOB (xml_document."XMLDATA"."Notes")
STORE AS (TABLESPACE USERS ENABLE STORAGE IN ROW
STORAGE(INITIAL 4K NEXT 32K))
COMPRESS FOR OLTP;

Note: In releases prior to Oracle Database 11gR2, the default
behavior for CREATE TABLE was to store a collection using a varray
stored as a LOB, not a varray stored as a table.

Note: When compression is specified for a parent XMLType table or
column, all descendant XMLType ordered collection tables (OCTs) are
similarly compressed.

See Also:
■

■

"Oracle XML Schema Annotations" on page 7-34 for information
about specifying storage options by using XML schema
annotations
Oracle Database SQL Language Reference for information about
compression for OLTP

As a convenience, if you need to specify that all varrays in an XMLType table or
column are to be stored as LOBs, or all are to be stored as tables, then you can use the
syntax clause STORE ALL VARRAYS AS, followed by LOBS or TABLES, respectively.
This is a convenient alternative to using multiple VARRAY...STORE AS clauses, one for
each collection. Example 7–23 illustrates this.
Example 7–23

Using STORE ALL VARRAYS AS

CREATE TABLE purchaseorder_as_table OF XMLType (UNIQUE ("XMLDATA"."Reference"),
FOREIGN KEY ("XMLDATA"."User") REFERENCES hr.employees (email))
ELEMENT
"http://xmlns.oracle.com/xdb/documentation/purchaseOrder.xsd#PurchaseOrder"
STORE ALL VARRAYS AS LOBS;

The storage method specified using STORE ALL VARRAYS AS overrides any storage
method specified using xdb:storeVarrayAsTable in the corresponding XML
schema.

XML Schema Storage and Query: Basic

7-33

Oracle XML Schema Annotations

See Also:
■

■

"Controlling How Collections Are Stored for Object-Relational
XMLType Storage" on page 3-19 for information about collection
storage using default tables
Oracle Database SQL Language Reference for information about
using STORE ALL VARRAYS AS LOBS

Specifying Relational Constraints on XMLType Tables and Columns
When you store XML data using structured storage, typical relational constraints can
be specified for elements and attributes that occur only once in an XML document.
Example 7–22 shows how to use object-relational notation to define a unique
constraint and a foreign key constraint when creating the table.
It is not possible to define constraints for XMLType tables and columns that make use
of unstructured storage.
See Also:
■

■

"Partitioning or Constraining Binary XML Data using Virtual
Columns" on page 3-3 for how to define constraints on XML data
stored as binary XML
"Adding Unique Constraints to the Parent Element of an
Attribute" on page 9-3

Oracle XML Schema Annotations
You can annotate XML schemas to influence the objects and tables that are generated
by the XML schema registration process. You do this by adding Oracle-specific
attributes to complexType, element, and attribute definitions that are declared
by the XML schema.
Most XML attributes used by Oracle XML DB belong to the namespace
http://xmlns.oracle.com/xdb. XML attributes used for encoding XML data as
binary XML belong to the namespace http://xmlns.oracle.com/2004/CSX. To
simplify the process of annotating an XML schema, Oracle recommends that you
declare namespace prefixes in the root element of the XML schema.

Common Uses of XML Schema Annotations
Common reasons for wanting to annotate an XML schema include the following:
■

■

■

■

To ensure that the names of the tables, objects, and object attributes created by
PL/SQL procedure DBMS_XMLSCHEMA.registerSchema for structured storage
of XML data are easy to recognize and compliant with any application-naming
standards. Set parameter GENTYPES or GENTABLES to TRUE for this.
To map between the XML schema and existing objects and tables within the
database. Set parameter GENTYPES or GENTABLES to FALSE for this.
To prevent the generation of mixed-case names that require the use of quoted
identifiers when working directly with SQL.
To allow XPath rewrite for structured storage in the case of document-correlated
recursive XPath queries. This applies to certain applications of SQL/XML access
and query functions whose XQuery-expression argument targets recursive XML
data.

7-34 Oracle XML DB Developer's Guide

Oracle XML Schema Annotations

The most commonly used XML schema annotations are the following:
■

■

■

■

■

■

xdb:defaultTable – Name of the default table generated for each global
element when parameter GENTABLES is TRUE. Setting this to the empty string, "",
prevents a default table from being generated for the element in question.
xdb:SQLName – Name of the SQL object attribute that corresponds to each
element or attribute defined in the XML schema.
xdb:SQLType – For complexType definitions, the corresponding object type. For
simpleType definitions, SQLType is used to override the default mapping
between XML schema data types and SQL data types. A common use of SQLType
is to define when unbounded strings should be stored as CLOB values, rather than
as VARCHAR(4000) CHAR values (the default). Note: You cannot use data type
NCHAR, NVARCHAR, or NCLOB as the value of a SQLType annotation.
xdb:SQLCollType – Used to specify the varray type that manages a collection of
elements.
xdb:maintainDOM – Used to determine whether or not DOM fidelity should be
maintained for a given complexType definition
xdb:storeVarrayAsTable – Specified in the root element of the XML schema.
Used to force all collections to be stored as ordered collection tables (OCTs). An
OCT is created for each element that is specified with maxOccurs > 1. The OCTs
are created with system-generated names. The default value of
storeVarrayAsTable is true.

You need not specify values for any of these attributes. Oracle XML DB provides
appropriate values by default during the XML schema registration process. However,
if you are using structured storage, then Oracle recommends that you specify the
names of at least the top-level SQL types, so that you can reference them later.

XML Schema Annotation Example
Example 7–24 shows a partial listing of the XML schema in Example 7–1, modified to
include some of the most important Oracle XML DB annotations.
Example 7–24

Using Common Schema Annotations











































The schema element includes the declaration of the xdb namespace. It also includes
the annotation xdb:storeVarrayAsTable = "true" (which is the default value).
This causes all collections within the XML schema to be managed using ordered
collection tables (OCTs).
The definition of global element PurchaseOrder includes a defaultTable
annotation that specifies that the name of the default table associated with this element
is purchaseorder.
The definition of global complex type PurchaseOrderType includes a SQLType
annotation that specifies that the generated SQL object type is named
purchaseorder_t. Within the definition of this type, the following annotations are
used:
■

■

■

The definition of element Reference includes a SQLName annotation that
specifies that the SQL attribute corresponding to XML element Reference is
named reference.
The definition of element Actions includes a SQLName annotation that specifies
that the SQL attribute corresponding to XML element Actions is named
action_collection.
The definition of element USER includes a SQLName annotation that specifies that
the SQL attribute corresponding to XML element User is named email.

7-36 Oracle XML DB Developer's Guide

Oracle XML Schema Annotations

■

■

The definition of element LineItems includes a SQLName annotation that
specifies that the SQL attribute corresponding to XML element LineItems is
named lineitem_collection.
The definition of element Notes includes a SQLType annotation that specifies that
the data type of the SQL attribute corresponding to XML element Notes is CLOB.

The definition of global complex type LineItemsType includes a SQLType
annotation that specifies that the generated SQL object type is named lineitems_t.
Within the definition of this type, the following annotations are used:
■

The definition of element LineItem includes a SQLName annotation that specifies
that the data type of the SQL attribute corresponding to XML element LineItems
is named lineitem_varray, and a SQLCollName annotation that specifies that
the SQL object type that manages the collection is named lineitem_v.

The definition of global complex type LineItemType includes a SQLType annotation
that specifies that generated SQL object type is named lineitem_t.
The definition of complex type PartType includes a SQLType annotation that
specifies that the SQL object type is named part_t. It also includes the annotation
xdb:maintainDOM = "false", specifying that there is no need for Oracle XML DB
to maintain DOM fidelity for elements based on this data type.
Example 7–25 shows some of the tables and objects that are created when the
annotated XML schema is registered.
Example 7–25

Registering an Annotated XML Schema

BEGIN
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'http://xmlns.oracle.com/xdb/documentation/purchaseOrder.xsd',
SCHEMADOC => bfilename('XMLDIR', 'purchaseOrder.Annotated.xsd'),
LOCAL
=> TRUE,
GENTYPES => TRUE,
GENTABLES => TRUE,
CSID
=> nls_charset_id('AL32UTF8'));
END;
/
SELECT table_name, xmlschema, element_name FROM USER_XML_TABLES;
TABLE_NAME
------------PURCHASEORDER

XMLSCHEMA
----------------------------------http://xmlns.oracle.com/xdb/documen
tation/purchaseOrder.xsd

ELEMENT_NAME
------------PurchaseOrder

1 row selected.
DESCRIBE purchaseorder
Name
Null? Type
------------------------------ ----- ----------------TABLE of SYS.XMLTYPE(XMLSchema
"http://xmlns.oracle.com/xdb/documentation/purchaseOrder.xsd"
ELEMENT "PurchaseOrder") STORAGE Object-relational TYPE "PURCHASEORDER_T"
DESCRIBE purchaseorder_t
PURCHASEORDER_T is NOT FINAL
Name
Null? Type

XML Schema Storage and Query: Basic

7-37

Oracle XML Schema Annotations

-------------------- ----- -------------------------SYS_XDBPD$
XDB.XDB$RAW_LIST_T
REFERENCE
VARCHAR2(30 CHAR)
ACTION_COLLECTION
ACTIONS_T
REJECT
REJECTION_T
REQUESTOR
VARCHAR2(128 CHAR)
EMAIL
VARCHAR2(10 CHAR)
COSTCENTER
VARCHAR2(4 CHAR)
SHIPPINGINSTRUCTIONS
SHIPPING_INSTRUCTIONS_T
SPECIALINSTRUCTIONS
VARCHAR2(2048 CHAR)
LINEITEM_COLLECTION
LINEITEMS_T
Notes
CLOB
DESCRIBE lineitems_t
LINEITEMS_T is NOT FINAL
Name
Null?
-------------------- ----SYS_XDBPD$
LINEITEM_VARRAY

Type
-------------------------XDB.XDB$RAW_LIST_T
LINEITEM_V

DESCRIBE lineitem_v
LINEITEM_V VARRAY(2147483647) OF LINEITEM_T
LINEITEM_T is NOT FINAL
Name
Null? Type
-------------------- ----- -------------------------SYS_XDBPD$
XDB.XDB$RAW_LIST_T
ITEMNUMBER
NUMBER(38)
DESCRIPTION
VARCHAR2(256 CHAR)
PART
PART_T
DESCRIBE part_t
PART_T is NOT FINAL
Name
Null? Type
-------------------- ----- -------------------------ID
VARCHAR2(14 CHAR)
QUANTITY
NUMBER(12,2)
UNITPRICE
NUMBER(8,4)
SELECT table_name, parent_table_column FROM USER_NESTED_TABLES
WHERE parent_table_name = 'purchaseorder';
TABLE_NAME
---------SYS_NTNOHV+tfSTRaDTA9FETvBJw==
SYS_NTV4bNVqQ1S4WdCIvBK5qjZA==

PARENT_TABLE_COLUMN
----------------------"XMLDATA"."LINEITEM_COLLECTION"."LINEITEM_VARRAY"
"XMLDATA"."ACTION_COLLECTION"."ACTION_VARRAY"

2 rows selected.

The following are results of this XML schema registration:
■
■

A table called purchaseorder was created.
Types called purchaseorder_t, lineitems_t, lineitem_v, lineitem_t,
and part_t were created. The attributes defined by these types are named
according to supplied the SQLName annotations.

■

The Notes attribute defined by purchaseorder_t is of data type CLOB.

■

Type part_t does not include a positional descriptor (PD) attribute.

7-38 Oracle XML DB Developer's Guide

Oracle XML Schema Annotations

■

Ordered collection tables (OCTs) were created to manage the collections of
LineItem and Action elements.

Available Oracle XML DB XML Schema Annotations
Table 7–3, Table 7–4, and Table 7–5 list Oracle XML DB annotations that you can
specify in element and attribute declarations. All annotations except those that have
the prefix csx are applicable to XML schemas registered for structured storage. This
includes the portions of hybrid storage that are stored object-relationally.
The following annotations apply to XML schemas that are registered for unstructured
storage:
■

xdb:defaultTable

■

xdb:defaultTableSchema

The following annotations apply to XML schemas that are registered for binary XML
storage:

Table 7–3

■

xdb:defaultTable

■

xdb:defaultTableSchema

■

xdb:tableProps

Annotations in Elements

Attribute

Values

Default

Description

xdb:columnProps

Any
column
storage
clause

NULL

Specifies the COLUMN storage clause that is inserted
into the default CREATE TABLE statement. It is
useful mainly for elements that get mapped to SQL
tables, namely top-level element declarations and
out-of-line element declarations.

xdb:defaultTable

Any table
name

Based on
element
name

Specifies the name of the SQL table into which XML
instances of this XML schema are stored. This is
most useful in cases where the XML data is inserted
from APIs and protocols, such as FTP and HTTP(S),
where the table name is not specified. Applicable to
structured storage and binary XML storage.

User
registering
XML schema

Name of the database user (database schema) who
owns the type specified by xdb:defaultTable.
Applicable to structured storage and binary XML
storage.

true

If true, then instances of this element are stored so
that they retain DOM fidelity on output. This
implies that all comments, processing instructions,
namespace declarations, and so on are retained, in
addition to the ordering of elements.

xdb:defaultTableSchema Any SQL
user name

xdb:maintainDOM

true |
false

If false, then the output is not guaranteed to have
the same DOM action as the input.

xdb:maintainOrder

true |
false

true

If true (generally recommended, and the default
value), then the collection is mapped to a varray
(stored in a LOB or an ordered collection table).
If false, then the collection is mapped to an
unordered table, and document order is not
preserved.

xdb:maxOccurs

Any
positive
integer

1

Specifies the maximum number of times an element
can appear. If the value is unbounded, then there is
no limit to the maximum number of occurrences.

XML Schema Storage and Query: Basic

7-39

Oracle XML Schema Annotations

Table 7–3 (Cont.) Annotations in Elements
Attribute

Values

Default

Description

xdb:SQLCollSchema

Any SQL
user name

User
registering
XML schema

Name of the database user (database schema) who
owns the type specified by xdb:SQLCollType.

xdb:SQLCollType

Any SQL
collection
type

Name
Name of the SQL collection type that corresponds
generated
to this XML element. The XML element must be
from element specified with maxOccurs > 1.
name

xdb:SQLInline

true |
false

true

If true, then this element is stored inline as an
embedded object attribute (or as a collection, if
maxOccurs > 1).
If false, then a REF value is stored (or a collection
of REF values, if maxOccurs > 1). This attribute is
forced to false in certain situations, such as cyclic
references, where SQL does not support inlining.

xdb:SQLName

Any SQL
identifier

Element
name

Name of the attribute within the SQL object that
maps to this XML element.

xdb:SQLSchema

Any SQL
user name

User
registering
XML schema

Name of the database user (database schema) who
owns the type specified by SQLType.

xdb:SQLType

Any SQL
data type1,
except
NCHAR,
NVARCHAR
, and
NCLOB

Name
Name of the SQL type corresponding to this XML
generated
element declaration.
from element
name

xdb:srclang

true |
false

true

If true, then the given language translation is used
as the default translation.

xdb:tableProps

Any table
storage
clause

NULL

Specifies the TABLE storage clause that is appended
to the default CREATE TABLE statement. This is
meaningful mainly for global and out-of-line
elements. Applicable to structured storage and
binary XML storage.

xdb:translate

true |
false

true

If true, then instances of this element are
translated. The maxOccurs attribute must be <=1
for this element to be set to true.

1

See "Mapping XML Schema Data Types to SQL Data Types" on page 7-45.

See Also: "Structured Storage of XML Schema-Based Data" on
page 7-32 for information about specifying storage options when
manually creating XMLType tables for object-relational storage

7-40 Oracle XML DB Developer's Guide

Oracle XML Schema Annotations

Table 7–4

Annotations in Elements Declaring Global complexType Elements

Attribute

Values

xdb:maintainDOM true | false

Default

Description

true

If true, then instances of this element are
stored so that they retain DOM fidelity on
output. This implies that all comments,
processing instructions, namespace
declarations, and so on are retained, in
addition to the ordering of elements.
If false, then the output is not
guaranteed to have the same DOM action
as the input.

xdb:SQLSchema

Any SQL user name

User registering XML
schema

xdb:SQLType

Any SQL data type1
except NCHAR,
NVARCHAR, and
NCLOB

Name generated from Name of the SQL type that corresponds to
element name
this XML element declaration.

1

Name of the database user (database
schema) who owns the type specified by
SQLType.

See "Mapping XML Schema Data Types to SQL Data Types" on page 7-45.

Table 7–5

Annotations in XML Schema Declarations

Attribute

Values

Default

xdb:mapUnboundedStringToLob true | false false

Description
If true, then unbounded strings are mapped
to CLOB instances by default. Similarly,
unbounded binary data gets mapped to a
BLOB value, by default.
If false, then unbounded strings are
mapped to VARCHAR2(4000) values, and
unbounded binary components are mapped
to RAW(2000) values.

true | false true

xdb:storeVarrayAsTable

If true, then the varray is stored as a table
(OCT).
If false, then the varray is stored in a LOB.

See Also: "Changing an XML Schema and XML Instance Documents
for Translation" on page 17 for more information on xdb:maxOccurs,
xdb:translate, and xdb:srclang.

XML Schema Annotation Guidelines for Structured Storage
For XMLType data stored object-relationally (structured storage), careful planning is
called for, to optimize performance. Similar considerations are in order as for ordinary
relational data: the entity-relationship model, indexing, data types, table partitions,
and so on.
To enable XPath rewrite and achieve optimal performance, you implement many such
design choices using XML schema annotations. This section provides annotation
guidelines to optimize the use of XMLType data stored object-relationally.
See Also:
■

Table 7–3, " Annotations in Elements" on page 7-39

■

Chapter 8, "XPath Rewrite for Structured Storage"

XML Schema Storage and Query: Basic

7-41

Oracle XML Schema Annotations

Avoid Creation of Unnecessary Tables for Unused Top-Level Elements
By default, XML schema registration creates a top-level table for each top-level
element defined in the XML schema. Some such elements are used as top-level
elements in XML instances that conform to the XML schema. Others might not. It is
common, for example, for elements in an XML schema to be top-level in order to be
used as a REF target.
Whenever a top-level element in an XML schema is never used at the top level in any
corresponding XML instance, you can avoid the creation of the associated unnecessary
tables by adding annotation xdb:defaultTable = "" to the element in the XML
schema. An empty value for this attribute prevents default-table creation.

Provide Your Own Names for Default Tables
For tuning purposes, you examine execution plan output for queries you are interested
in. This output refers to the tables that underlie XMLType data stored
object-relationally. By default, these tables have system-generated names. Oracle
recommends that you provide your own table names, especially for tables that you are
sure to be interested in. You do that using annotation xdb:defaultTable.
See Also: "Default Tables Created During XML Schema
Registration" on page 7-10

Turn Off DOM Fidelity If Not Needed
By default, XML schema registration generates tables that store XML data in such a
way that DOM fidelity is maintained. It is often the case that for data-centric XML data
DOM fidelity is not needed. You can improve the performance of storage, queries, and
data modification by instead using object-relational tables that do not maintain DOM
fidelity. You use the annotation xdb:maintainDOM = "false" to do that.
See Also:

"DOM Fidelity" on page 7-16

Use Unordered Collection Elements When Order Doesn't Matter
If the order among collection elements is not important, then use annotation
xdb:maintainOrder = "false". This can allow more optimization in XPath
rewrite and can generally lead to more efficient query execution.

Annotate Time-Related Elements with a Timestamp Data Type
If your application needs to work with time-zone indicators, then annotate any XML
schema elements of type xs:time and xs:dateTime with xdb:SQLType =
"TIMESTAMP WITH TIME ZONE". This ensures that values containing time-zone
indicators can be stored, retrieved, and compared.

Add Table and Column Properties
If a table or column underlying XML data needs additional properties, such as
partition, tablespace, or compression clauses, then use annotation xdb:tableProps
or xdb:columnProps to provide them. This lets users add primary keys or
constraints. For example, to achieve table compression for online transaction
processing (OLTP), you would add COMPRESS FOR OLTP using a tableProps
attribute.
See Also: Example 7–22 on page 7-32 for an example of specifying
OLTP compression when creating XMLType tables and columns
manually

7-42 Oracle XML DB Developer's Guide

Querying a Registered XML Schema to Obtain Annotations

Store Large Collections Out of Line
When the total number of elements and attributes defined by a complexType reaches
1000, it is not possible to create a single table that can manage the SQL objects that are
generated when an instance of that type is stored in the database. If you have large
collections, then you might run up against this limit of 1000 columns for a table.
You can use annotations xdb:defaultTable and xdb:SQLInline to specify that
such collection elements be stored out of line. That means that their data is stored in a
separate table—only a reference to a row in that table is stored in the main collection
table. Use xdb:defaultTable to name the out-of -line table. Annotate each element
of a potentially large collection with xdb:SQLInline = "false", to store it out of
line.
See Also:
■
■

"Working with Large XML Schemas" on page 3-26
"Setting Annotation Attribute SQLInline to false for Out-Of-Line
Storage" on page 9-4

Querying a Registered XML Schema to Obtain Annotations
The registered version of an XML schema contains a full set of Oracle XML DB
annotations. As shown in Example 7–8 and Example 7–9, the location of the registered
XML schema depends on whether it is local or global.
A registered XML schema can be queried for the annotations that were supplied by the
user or added by the schema registration process. Example 7–26 shows the set of
global complexType definitions declared by an XML schema for structured storage of
XML data, and the corresponding SQL object types and DOM fidelity values.
Example 7–26

Querying Metadata from a Registered XML Schema

SELECT ct.xmlschema_type_name, ct.sql_type_name, ct.dom_fidelity
FROM RESOURCE_VIEW,
XMLTable(
XMLNAMESPACES (
'http://xmlns.oracle.com/xdb/XDBResource.xsd' AS "r",
'http://xmlns.oracle.com/xdb/documentation/purchaseOrder' AS "po",
'http://www.w3.org/2001/XMLSchema' AS "xs",
'http://xmlns.oracle.com/xdb' AS "xdb"),
'/r:Resource/r:Contents/xs:schema/xs:complexType' PASSING RES
COLUMNS
xmlschema_type_name VARCHAR2(30) PATH '@name',
sql_type_name
VARCHAR2(30) PATH '@xdb:SQLType',
dom_fidelity
VARCHAR2(6) PATH '@xdb:maintainDOM') ct
WHERE
equals_path(
RES,
'/sys/schemas/SCOTT/xmlns.oracle.com/xdb/documentation/purchaseOrder.xsd')
=1;
XMLSCHEMA_TYPE_NAME
------------------------PurchaseOrderType
LineItemsType
LineItemType
PartType
ActionsType
RejectionType

SQL_TYPE_NAME
----------------------PURCHASEORDER_T
LINEITEMS_T
LINEITEM_T
PART_T
ACTIONS_T
REJECTION_T

DOM_FIDELITY
-----------true
true
true
true
true
true

XML Schema Storage and Query: Basic

7-43

Mapping XML Schema Data Types to Oracle XML DB Storage

ShippingInstructionsType

SHIPPING_INSTRUCTIONS_T

true

7 rows selected.

Mapping XML Schema Data Types to Oracle XML DB Storage
XML data that conforms to an XML schema is typed using XML Schema data types.
When this XML data is stored in Oracle XML DB, its storage data types are derived
from the XML Schema data types using a default mapping and, optionally, using
mapping information that you specify using XML schema annotations.
Whenever you do not specify a data type to use for storage, Oracle XML DB uses the
default mapping to annotate the XML schema appropriately, during registration. In
this way, the registered XML schema has a complete set of data-type annotations.
■

■
■

For unstructured storage, the data-type mapping is trivial: all of the XML data is
stored together as a single CLOB.
For structured storage, XML Schema data types are mapped to SQL data types.
For binary XML storage, XML Schema data types are mapped to Oracle XML DB
binary XML encoding types.
See Also: "Mapping XML Schema Data Types to SQL Data Types"
on page 7-45

Figure 7–5 shows how Oracle XML DB creates XML schema-based XMLType tables
using an XML document and a mapping specified in an XML schema. Depending on
the storage method specified in the XML schema, an XML instance document is stored
either as a binary XML or CLOB value in a single XMLType column, or using multiple
object-relational columns.

7-44 Oracle XML DB Developer's Guide

Mapping XML Schema Data Types to SQL Data Types

Figure 7–5 How Oracle XML DB Maps XML Schema-Based XMLType Tables
XML instance document: employees.xml
...

Shelli
Baida
sbaida
...
24-DEC-97
...
30

...

Create
XMLType
Table

XML schema: employees.xsd
...




...

...


...
Binary XML Storage

Unstructured Storage

employees Tables

Structured
Storage

employees Tables

employees Tables

...

XMLType
Column

...

...

...

XMLType
Column

...

...

first_name last_name email

...
...
...
...
...

Binary XML
Binary XML
Binary XML
Binary XML
Binary XML

...
...
...
...
...

...
...
...
...
...

...
...
...
...
...

CLOB
CLOB
CLOB
CLOB
CLOB

...
...
...
...
...

...
...
...
...
...

shelli

XML data stored as
binary XML

XML data stored as
CLOB instances

baida

sbaida

dept_id
30

XML data stored in
object-relational columns and tables

Mapping XML Schema Data Types to SQL Data Types
This section describes how to use PL/SQL package DBMS_XMLSCHEMA to map data
types for XML Schema attributes and elements to SQL data types.
Note: Do not directly access the SQL data types that are mapped
from XML Schema data types during XML schema registration. These
SQL types are part of the implementation of Oracle XML DB. They are
not exposed for your use.

Oracle reserves the right to change the implementation at any time,
including in a product patch. Such a change by Oracle will have no
effect on applications that abide by the XML abstraction, but it might
impact applications that directly access these data types.

Example of Mapping XML Schema Data Types to SQL
Example 7–27 shows a simple example of mapping XML Schema data types to SQL
data types. It uses attribute SQLType to specify the data-type mapping. It also uses

XML Schema Storage and Query: Basic

7-45

Mapping XML Schema Data Types to SQL Data Types

attribute SQLName to specify the object attributes to use for various XML elements and
attributes.
Example 7–27

Mapping XML Schema Data Types to SQL Data Types using Attribute SQLType









































...











7-46 Oracle XML DB Developer's Guide

Mapping XML Schema Data Types to SQL Data Types

















...


Mapping XML Schema Attribute Data Types to SQL
An attribute declaration can specify its XML Schema data type in terms of one of the
following:
■
■

■

■

Primitive type
Global simpleType, declared within this XML schema or in an external XML
schema
Reference to global attribute (ref=".."), declared within this XML schema or in
an external XML schema
Local simpleType

In all cases, the SQL data type, its associated information (length, precision), and the
memory mapping information are derived from the simpleType on which the
attribute is based.

Overriding the SQLType Value in an XML Schema When Declaring Attributes
You can explicitly specify a SQLType value in the input XML schema document. In
this case, the data type you specify is used for schema validation. This allows for the
following specific forms of overrides:
■

■

If the default SQL data type is STRING, you can override it with CHAR, VARCHAR,
or CLOB.
If the default SQL data type is RAW, you can override it with RAW or BLOB.

Mapping XML Schema Element Data Types to SQL
An element declaration can specify its XML Schema data type in terms of one of the
following:
■

■

■

■

Any of the ways for specifying type for an attribute declaration. See "Mapping
XML Schema Attribute Data Types to SQL" on page 7-47.
Global complexType, specified within this XML schema document or in an
external XML schema.
Reference to a global element (ref="..."), which could itself be within this XML
schema document or in an external XML schema.
Local complexType.

XML Schema Storage and Query: Basic

7-47

Mapping XML Schema Data Types to SQL Data Types

Overriding the SQLType Value in an XML Schema when Declaring Elements
An element based on a complexType is, by default, mapped to a SQL object type that
contains object attributes corresponding to each of the sub-elements and attributes.
You can override this mapping by explicitly specifying a value for attribute SQLType
in the input XML schema. The following values for SQLType are permitted here:
■

VARCHAR2

■

RAW

■

CLOB

■

BLOB

These represent storage of the XML data in a text form in the database.
For example, to override the SQLType from VARCHAR2 to CLOB, declare the xdb
namespace using xmlns:xdb="http://xmlns.oracle.com/xdb", and then use
xdb:SQLType = "CLOB".
The following special cases are handled:
■

■

■

If a cycle is detected when processing the complexType values that are used to
declare elements and the elements declared within the complexType, the
SQLInline attribute is forced to be false, and the correct SQL mapping is set to
REF XMLType.
If maxOccurs > 1, a varray type might be created.
–

If SQLInline = "true", then a varray type is created whose element type is
the SQL data type previously determined. Cardinality of the varray is based
on the value of attribute maxOccurs. Either you specify the name of the
varray type using attribute SQLCollType, or it is derived from the element
name.

–

If SQLInline = "false", then the SQL data type is set to
XDB.XDB$XMLTYPE_REF_LIST_T. This is a predefined data type that
represents an array of REF values pointing to XMLType instances.

If the element is a global element, or if SQLInline = "false", then the system
creates a default table. Either you specify the name of the default table, or it is
derived from the element name.
See Also: Chapter 9, "XML Schema Storage and Query:
Advanced" for more information about mapping simpleType
values and complexType values to SQL.

Mapping simpleType to SQL
This section describes how XML schema definitions map XML Schema simpleType
to SQL object types. Figure 7–6 shows an example of this.

7-48 Oracle XML DB Developer's Guide

Mapping XML Schema Data Types to SQL Data Types

Figure 7–6 Mapping simpleType: XML Strings to SQL VARCHAR2 or CLOB
.
.
.

.
.
.

Employee_tab of type OBJ_T
...
...
Resume . . .
...

...

CLOB

...

Entire resume
value is stored
in the CLOB

Table 7–6 through Table 7–9 present the default mapping of XML Schema
simpleType to SQL, as specified in the XML Schema definition. For example:
■

■

■

Table 7–6

A XML Schema primitive type is mapped to the closest SQL data type. For
example, DECIMAL, POSITIVEINTEGER, and FLOAT are all mapped to SQL
NUMBER.
An XML Schema enumeration type is mapped to a SQL object type with a single
RAW(n) object attribute. The value of n is determined by the number of possible
values in the enumeration declaration.
An XML Schema list or a union type is mapped to a SQL string (VARCHAR2 or
CLOB) data type.

Mapping XML Schema String Data Types to SQL

XML Schema
String Type

Length or
MaxLength
Facet
Default SQL Data Type

Compatible SQL Data
Type

string

n

VARCHAR2(n) if n < 4000, else VARCHAR2(4000)

CHAR, CLOB

string

-

VARCHAR2(4000) if mapUnboundedStringToLob =
"false", CLOB

CHAR, CLOB

Table 7–7

Mapping XML Schema Binary Data Types (hexBinary/base64Binary) to SQL

XML Schema Binary Type

Compatible
SQL Data
Type

Length or
MaxLength
Facet
Default SQL Data Type

hexBinary, base64Binary n

RAW(n) if n < 2000, else RAW(2000)

RAW, BLOB

hexBinary, base64Binary -

RAW(2000) if mapUnboundedStringToLob =
"false", BLOB

RAW, BLOB

Table 7–8

Default Mapping of Numeric XML Schema Primitive Types to SQL

XML Schema Simple
Type

Default SQL
Data Type

totalDigits (m),
fractionDigits(n) Specified Compatible SQL Data Types

float

NUMBER

NUMBER(m+n,n)

FLOAT, DOUBLE, BINARY_FLOAT

double

NUMBER

NUMBER(m+n,n)

FLOAT, DOUBLE, BINARY_DOUBLE

decimal

NUMBER

NUMBER(m+n,n)

FLOAT, DOUBLE

XML Schema Storage and Query: Basic

7-49

Mapping XML Schema Data Types to SQL Data Types

Table 7–8 (Cont.) Default Mapping of Numeric XML Schema Primitive Types to SQL
XML Schema Simple
Type

Default SQL
Data Type

totalDigits (m),
fractionDigits(n) Specified Compatible SQL Data Types

integer

NUMBER

NUMBER(m+n,n)

NUMBER

nonNegativeInteger NUMBER

NUMBER(m+n,n)

NUMBER

positiveInteger

NUMBER

NUMBER(m+n,n)

NUMBER

nonPositiveInteger NUMBER

NUMBER(m+n,n)

NUMBER

negativeInteger

NUMBER

NUMBER(m+n,n)

NUMBER

long

NUMBER(20)

NUMBER(m+n,n)

NUMBER

unsignedLong

NUMBER(20)

NUMBER(m+n,n)

NUMBER

int

NUMBER(10)

NUMBER(m+n,n)

NUMBER

unsignedInt

NUMBER(10)

NUMBER(m+n,n)

NUMBER

short

NUMBER(5)

NUMBER(m+n,n)

NUMBER

unsignedShort

NUMBER(5)

NUMBER(m+n,n)

NUMBER

byte

NUMBER(3)

NUMBER(m+n,n)

NUMBER

unsignedByte

NUMBER(3)

NUMBER(m+n,n)

NUMBER

Table 7–9

Mapping XML Schema Date and Time Data Types to SQL

XML Schema Date or Time Type

Default SQL Data Type

Compatible SQL Data Types

dateTime

TIMESTAMP

TIMESTAMP WITH TIME ZONE, DATE

time

TIMESTAMP

TIMESTAMP WITH TIME ZONE, DATE

date

DATE

TIMESTAMP WITH TIME ZONE

gDay

DATE

TIMESTAMP WITH TIME ZONE

gMonth

DATE

TIMESTAMP WITH TIME ZONE

gYear

DATE

TIMESTAMP WITH TIME ZONE

gYearMonth

DATE

TIMESTAMP WITH TIME ZONE

gMonthDay

DATE

TIMESTAMP WITH TIME ZONE

duration

VARCHAR2(4000)

none

Table 7–10

Default Mapping of Other XML Schema Primitive and Derived Data Types to SQL

XML Schema Primitive or Derived
Type
Default SQL Data Type

Compatible SQL Data
Types

boolean

RAW(1)

VARCHAR2

language(string)

VARCHAR2(4000)

CLOB, CHAR

NMTOKEN(string)

VARCHAR2(4000)

CLOB, CHAR

NMTOKENS(string)

VARCHAR2(4000)

CLOB, CHAR

Name(string)

VARCHAR2(4000)

CLOB, CHAR

NCName(string)

VARCHAR2(4000)

CLOB, CHAR

ID

VARCHAR2(4000)

CLOB, CHAR

IDREF

VARCHAR2(4000)

CLOB, CHAR

7-50 Oracle XML DB Developer's Guide

Mapping XML Schema Data Types to SQL Data Types

Table 7–10 (Cont.) Default Mapping of Other XML Schema Primitive and Derived Data Types to SQL
XML Schema Primitive or Derived
Type
Default SQL Data Type

Compatible SQL Data
Types

IDREFS

VARCHAR2(4000)

CLOB, CHAR

ENTITY

VARCHAR2(4000)

CLOB, CHAR

ENTITIES

VARCHAR2(4000)

CLOB, CHAR

NOTATION

VARCHAR2(4000)

CLOB, CHAR

anyURI

VARCHAR2(4000)

CLOB, CHAR

anyType

VARCHAR2(4000)

CLOB, CHAR

anySimpleType

VARCHAR2(4000)

CLOB, CHAR

QName

XDB.XDB$QNAME

none

normalizedString

VARCHAR2(4000)

none

token

VARCHAR2(4000)

none

NCHAR, NVARCHAR, and NCLOB SQLType Values are Not Supported
Oracle XML DB does not support NCHAR, NVARCHAR, and NCLOB as values for
attribute SQLType: you cannot specify that an XML element or attribute is to be of
type NCHAR, NVARCHAR, or NCLOB. Also, if you provide your own data type, do not
use any of these data types.
See Also:

Appendix B, "Oracle XML DB Restrictions"

simpleType: Mapping XML Strings to SQL VARCHAR2 Versus CLOB
If an XML schema specifies an XML Schema data type to be a string with a
maxLength less than 4000, then it is mapped to a VARCHAR2 object attribute of the
specified length. However, if maxLength is not specified in the XML schema, then it
can only be mapped to a LOB. This is sub-optimal when most of the string values are
small and only a small fraction of them are large enough to need a LOB.
See Also: Table 7–6, " Mapping XML Schema String Data Types to
SQL"

Working with Time Zones
The following XML Schema data types allow for an optional time-zone indicator as
part of their literal values.
■

xsd:dateTime

■

xsd:time

■

xsd:date

■

xsd:gYear

■

xsd:gMonth

■

xsd:gDay

■

xsd:gYearMonth

■

xsd:gMonthDay

XML Schema Storage and Query: Basic

7-51

Mapping XML Schema Data Types to SQL Data Types

By default, XML schema registration maps xsd:dateTime and xsd:time to SQL
data type TIMESTAMP and all the other data types to SQL data type DATE. SQL data
types TIMESTAMP and DATE do not permit a time-zone indicator.
If your application needs to work with time-zone indicators, then use attribute
SQLType to specify the SQL data type as TIMESTAMP WITH TIME ZONE. This
ensures that values containing time-zone indicators can be stored and retrieved
correctly. For example:



Using Trailing Z to Indicate UTC Time Zone XML Schema lets the time-zone component be
specified as Z, to indicate UTC time zone. When a value with a trailing Z is stored in a
SQL TIMESTAMP WITH TIME ZONE column, the time zone is actually stored as
+00:00. Thus, the retrieved value contains the trailing +00:00, not the original Z. For
example, if the value in the input XML document is 1973-02-12T13:44:32Z, the
output is 1973-02-12T13:44:32.000000+00:00.

Mapping complexType to SQL
Using XML Schema, a complexType is mapped to a SQL object type as follows:
■

■

XML attributes declared within the complexType are mapped to SQL object
attributes. The simpleType defining an XML attribute determines the SQL data
type of the corresponding object attribute.
XML elements declared within the complexType are also mapped to SQL object
attributes. The simpleType or complexType defining an XML element
determines the SQL data type of the corresponding object attribute.

If the XML element is declared with attribute maxOccurs > 1, then it is mapped to a
SQL collection (object) attribute. The collection could be a varray value (the default,
recommended) or an unordered table (if you set attribute xdb:maintainOrder to
false). The default storage of a varray value is an ordered collections table (OCT).
You can choose LOB storage instead, by setting attribute xdb:storeVarrayAsTable
to false.

Specifying Attributes in a complexType XML Schema Declaration
When you have an element based on a global complexType, both the SQLType and
SQLSchema attributes must be specified for the complexType declaration. In
addition you can optionally include the same SQLType and SQLSchema attributes
within the element declaration.
If you do not specify attribute SQLType for the global complexType, Oracle XML DB
creates a SQLType attribute with an internally generated name. The elements that
reference this global type cannot then have a different value for SQLType. The
following code is acceptable:








7-52 Oracle XML DB Developer's Guide

Mapping XML Schema Data Types to SQL Data Types



















XML Schema Storage and Query: Basic

7-53

Mapping XML Schema Data Types to SQL Data Types

7-54 Oracle XML DB Developer's Guide

8
XPath Rewrite for Structured Storage
This chapter explains the fundamentals of XPath rewrite for structured
(object-relational) storage in Oracle XML DB. It details the rewriting of
XPath-expression arguments to various SQL functions.
This chapter contains these topics:
■

Overview of XPath Rewrite for Structured Storage

■

Sample of XPath Expressions that Are Rewritten

■

Analyzing and Optimizing XPath Queries using Execution Plans
See Also:

"Performance Tuning for XQuery" on page 5-29

Overview of XPath Rewrite for Structured Storage
Oracle XML DB can often optimize queries that use XPath expressions—for example,
queries involving SQL functions such as XMLQuery, XMLTable, XMLExists, and
updateXML, which take XPath (XQuery) expressions as arguments. The XPath
expression is, in effect, evaluated against the XML document without ever
constructing the XML document in memory.
This optimization is called XPath rewrite. It is a proper subset of XML query
optimization, which also involves optimization of XQuery expressions, such as
FLWOR expressions, that are not XPath expressions. XPath rewrite also enables
indexes, if present on the column, to be used in query evaluation by the Optimizer.
The XPath expressions that can be rewritten by Oracle XML DB are a proper subset of
those that are supported by Oracle XML DB. Whenever you can do so without losing
functionality, use XPath expressions that can be rewritten.
XPath rewrite can occur in these contexts (or combinations thereof):
■

■
■

When XMLType data is stored in an object-relational column or table (structured
storage) or when an XMLType view is built on relational data.
When you use an XMLIndex index. See "XMLIndex" on page 6-7.
When XMLType data is stored as binary XML. See "How Oracle XML DB Processes
XMLType Methods and SQL Functions" on page 3-58 for information about
streaming evaluation.

This chapter covers the first case: rewriting queries that use structured XML data or
XMLType views. The XMLType views can be XML schema-based or not. Structured
storage of XMLType data is always XML schema-based. Examples in this chapter are
related to XML schema-based tables.

XPath Rewrite for Structured Storage 8-1

Sample of XPath Expressions that Are Rewritten

Example 8–1 illustrates XPath rewrite for a simple query that uses an XPath
expression.
Example 8–1 XPath Rewrite
SELECT po.OBJECT_VALUE FROM purchaseorder po
WHERE XMLCast(XMLQuery('$p/PurchaseOrder/Requestor'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(128))
= 'Sarah J. Bell';

The XMLCast(XMLQuery...)) expression here is rewritten to the underlying
relational column that stores the requestor information for the purchase order. The
query is rewritten to something like the following:1
SELECT OBJECT_VALUE FROM purchaseorder p
WHERE CAST (p."XMLDATA"."REQUESTOR" AS VARCHAR2(128)) = 'Sarah J. Bell';

Sample of XPath Expressions that Are Rewritten
Table 8–1 describes some XPath expressions that are rewritten during XPath rewrite.
Table 8–1

Sample of XPath Expressions that Are Rewritten to Underlying SQL Constructs

XPath Expression for Translation

Description

Simple XPath expressions (expressions with child and
attribute axes only):

Involves traversals over object type attributes only,
where the attributes are simple scalar or object types
themselves.

/PurchaseOrder/@Reference
/PurchaseOrder/Requestor
Collection traversal expressions:
/PurchaseOrder/LineItems/LineItem/Part/@Id

Predicates:
[Requestor = "Sarah J. Bell"]
List index (positional predicate):
LineItem[1]
Wildcard traversals:
/PurchaseOrder/*/Part/@Id

1

Involves traversal of collection expressions. The only
axes supported are child and attribute axes.
Collection traversal is not supported if the SQL
function is used during a CREATE INDEX operation.
Predicates in the XPath are rewritten into SQL
predicates.
Indexes are rewritten to access the nth item in a
collection.
If the wildcard can be translated to one or more
simple XPath expressions, then it is rewritten.

This example uses sample database schema OE and its table purchaseorder. The XML
schema for this table is annotated with attribute SQLName to specify SQL object attribute
names such as REQUESTOR—see Example 3–10 on page 3-20. Without such annotations, this
example would use p."XMLDATA"."Requestor", not p."XMLDATA".".REQUESTOR".

8-2 Oracle XML DB Developer's Guide

Analyzing and Optimizing XPath Queries using Execution Plans

Table 8–1 (Cont.) Sample of XPath Expressions that Are Rewritten to Underlying SQL Constructs
XPath Expression for Translation

Description

Descendant axis (XML schema-based data only), without
recursion:
/PurchaseOrder//Part/@Id

Similar to a wildcard expression. The descendant
axis is rewritten if it can be mapped to one or more
simple XPath expressions.

Descendant axis (XML schema-based data only), with
recursion:

The descendant axis is rewritten if both of these
conditions holds:

/PurchaseOrder//Part/@Id

■

■

XPath functions

All simple XPath expressions to which this
XPath expression expands map to the same
out-of-line table.
Any simple XPath expression to which this
XPath expression does not expand does not map
to that out-of-line table.

Some XPath functions are rewritten. These functions
include not, floor, ceiling, substring, and
string-length.

See Also: "Performance Tuning for XQuery" on page 5-29 for
information about rewrite of XQuery expressions

Analyzing and Optimizing XPath Queries using Execution Plans
This section presents some guidelines for using execution plans to do the following,
for queries that use XPath expressions:
■

Analyze query execution, to determine whether XPath rewrite occurs.

■

Optimize query execution, by using secondary indexes.

Use these guidelines together, taking all that apply into consideration.
As is true also for the rest of this chapter, this section is applicable only to XMLType
data that is stored object-relationally (structured storage).
XPath rewrite for object-relational storage means that a query that selects XML
fragments defined by an XPath expression is rewritten to a SQL SELECT statement on
the underlying object-relational tables and columns. These underlying tables can
include out-of-line tables.
See Also:

"XPath Rewrite for Out-Of-Line Tables" on page 9-7

Guideline: Look for underlying tables versus XML functions in execution plans
The execution plan of a query that has been rewritten refers to the object-relational
tables and columns that underlie the queried XMLType data.
The names of the underlying tables can be meaningful to you, if they are derived from
XML element or attribute names or if the governing XML schema explicitly names
them by using annotation xdb:defaultTable. Otherwise, these names are
system-generated and have no obvious meaning. In particular, they do not reflect the
corresponding XML element or attribute names. Also, some system-generated
columns are hidden. You do not see them if you use the SQL describe command.
They nevertheless show up in execution plans.
The plan of a query that has not been rewritten shows only the base table names, and
it typically refers to user-level XML functions, such as XMLExists. Look for this
difference to determine whether a query has been optimized. The XML function name

XPath Rewrite for Structured Storage 8-3

Analyzing and Optimizing XPath Queries using Execution Plans

shown in an execution plan is actually the internal name (for example, XMLEXISTS2),
which is sometimes slightly different from the user-level name.
Example 8–2 shows the kind of execution plan output that is generated when Oracle
XML DB cannot perform XPath rewrite. The plan here is for a query that uses
SQL/XML function XMLExists. The corresponding internal function XMLExists2
appears in the plan output, indicating that the query is not rewritten.
Example 8–2 Execution Plan Generated When XPath Rewrite Does Not Occur
Predicate Information (identified by operation id):
--------------------------------------------------1 - filter(XMLEXISTS2('$p/PurchaseOrder[User="SBELL"]' PASSING BY VALUE
SYS_MAKEXML('61687B202644E297E040578C8A175C1D',4215,"PO"."XMLEXTRA","PO"."X
MLDATA") AS "p")=1)

In this situation, Oracle XML DB constructs a pre-filtered result set based on any other
conditions specified in the query WHERE clause. It then filters the rows in this potential
result set to determine which rows belong in the result set. The filtering is performed
by constructing a DOM on each document and performing a functional evaluation (using
the methods defined by the DOM API) to determine whether or not each document is
a member of the result set.

Guideline: Name the default tables, so you recognize them in execution plans
When designing an XML schema, use annotation xdb:defaultTable to name the
underlying tables that correspond to elements that you select in queries where
performance is important. This lets you easily recognize them in an execution plan,
indicating by their presence or absence whether the query has been rewritten.

Guideline: Create an index on a column targeted by a predicate
A query resulting from XPath rewrite sometimes includes a SQL predicate (WHERE
clause). This can happen even if the original query does not use an XPath predicate,
and it can happen even if the original query does not have a SQL WHERE clause.
When this happens, you can sometimes improve performance by creating an index on
the column that is targeted by the SQL predicate, or by creating an index on a function
application to that column. Example 8–1 illustrates XPath rewrite for a query that
includes a WHERE clause. Example 8–3 shows the predicate information from an
execution plan for this query.
Example 8–3 Analyzing an Execution Plan to Determine a Column to Index
Predicate Information (identified by operation id):
--------------------------------------------------1 - filter(CAST("PURCHASEORDER"."SYS_NC00021$" AS VARCHAR2(128))='Sarah
J. Bell' AND SYS_CHECKACL("ACLOID","OWNERID",xmltype(''))=1)

The predicate information indicates that the expression XMLCast(XMLQuery...)) is
rewritten to an application of SQL function cast to the underlying relational column
that stores the requestor information for the purchase order, SYS_NC0021$. This
8-4 Oracle XML DB Developer's Guide

Analyzing and Optimizing XPath Queries using Execution Plans

column name is system-generated. The execution plan refers to this system-generated
name, in spite of the fact that the governing XML schema uses annotation SQLName to
name this column REQUESTOR.
Because these two names (user-defined and system-generated) refer to the same
column, you can create a B-tree index on this column using either name. Alternatively,
you can use the extractValue shortcut to create the index, by specifying an XPath
expression that targets the purchase-order requestor data. Example 8–4 shows these
three equivalent ways to create the B-tree index on the predicate-targeted column.
Example 8–4 Creating an Index on a Column Targeted by a Predicate
CREATE INDEX requestor_index ON purchaseorder ("SYS_NC00021$");
CREATE INDEX requestor_index ON purchaseorder ("XMLDATA"."REQUESTOR");
CREATE INDEX requestor_index ON purchaseorder
(extractvalue(OBJECT_VALUE, '/PurchaseOrder/Requestor'));

However, for this particular query it makes sense to create a function-based index,
using a functional expression that matches the one in the rewritten query. Example 8–5
illustrates this.
Example 8–5 Creating a Function-Based Index for a Column Targeted by a Predicate
CREATE INDEX requestor_index ON purchaseorder
(cast("XMLDATA"."REQUESTOR" AS VARCHAR2(128)));

Example 8–6 shows an execution plan that indicates that the index is picked up.
Example 8–6 Execution Plan Showing that Index Is Picked Up
----------------------------------------------------------------------------------------------| Id | Operation
| Name
| Rows | Bytes | Cost (%CPU)| Time
|
----------------------------------------------------------------------------------------------|
0 | SELECT STATEMENT
|
|
1 |
524 |
2
(0)| 00:00:01 |
|* 1 | TABLE ACCESS BY INDEX ROWID| PURCHASEORDER
|
1 |
524 |
2
(0)| 00:00:01 |
|* 2 |
INDEX RANGE SCAN
| REQUESTOR_INDEX |
1 |
|
1
(0)| 00:00:01 |
----------------------------------------------------------------------------------------------Predicate Information (identified by operation id):
--------------------------------------------------1 - filter(SYS_CHECKACL("ACLOID","OWNERID",xmltype('
'))=1)
2 - access(CAST("SYS_NC00021$" AS VARCHAR2(128))='Sarah J. Bell')

In the particular case of this query, the original functional expression applies XMLCast
to XMLQuery to target a singleton element, Requestor. This is a special case, where
you can as a shortcut use such a functional expression directly in the CREATE INDEX
statement. That statement is rewritten to create an index on the underlying scalar data.
Example 8–7, which targets an XPath expression, thus has the same effect as
Example 8–5, which targets the corresponding object-relational column.

XPath Rewrite for Structured Storage 8-5

Analyzing and Optimizing XPath Queries using Execution Plans

Example 8–7 Creating a Function-Based Index for a Column Targeted by a Predicate
CREATE INDEX requestor_index
ON purchaseorder po
(XMLCast(XMLQuery('$p/PurchaseOrder/Requestor' PASSING po.OBJECT_VALUE AS "p"
RETURNING CONTENT)
AS VARCHAR2(128)));

See Also: "Indexing Non-Repeating text() Nodes or Attribute
Values" on page 6-6 for information about using the shortcut of
XMLCast applied to XMLQuery and the extractValue shortcut to
index singleton data

Guideline: Create indexes on ordered collection tables
If a collection is stored as an ordered collection table or an XMLType instance, then you
can directly access members of the collection. Each member of the collection becomes a
row in a table, so you can access it directly with SQL.
You can often improve performance by indexing such collection members. You do this
by creating a composite index on (a) the object attribute that corresponds to the
collection XML element or its attribute and (b) pseudocolumn NESTED_TABLE_ID.
Example 8–8 shows the execution plan for a query to find the Reference elements in
documents that contain an order for part number 717951002372 (Part element with an
Id attribute of value 717951002372). The collection of LineItem elements is stored
as rows in the ordered collection table lineitem_table.
Note: Example 8–8 does not use the purchaseorder table from
sample database schema OE. It uses the purchaseorder table
defined in Example 3–13 on page 3-28. This table uses an ordered
collection table (OCT) named lineitem_table for the collection
element LineItem.
Example 8–8 Execution Plan for a Selection of Collection Elements
SELECT XMLCast(XMLQuery('$p/PurchaseOrder/Reference'
PASSING OBJECT_VALUE AS "p" RETURNING CONTENT)
AS VARCHAR2(4000)) "Reference"
FROM purchaseorder
WHERE XMLExists('$p/PurchaseOrder/LineItems/LineItem/Part[@Id="717951002372"]'
PASSING OBJECT_VALUE AS "p");
------------------------------------------------------------------------------------------------------| Id | Operation
| Name
| Rows | Bytes | Cost (%CPU)| Time
|
------------------------------------------------------------------------------------------------------|
0 | SELECT STATEMENT
|
|
1 |
122 |
16 (13)| 00:00:01 |
|
1 | NESTED LOOPS
|
|
|
|
|
|
|
2 |
NESTED LOOPS
|
|
1 |
122 |
16 (13)| 00:00:01 |
|
3 |
SORT UNIQUE
|
|
1 |
50 |
14
(8)| 00:00:01 |
|* 4 |
TABLE ACCESS FULL
| LINEITEM_TABLE
|
1 |
50 |
14
(8)| 00:00:01 |
|* 5 |
INDEX UNIQUE SCAN
| LINEITEM_TABLE_MEMBERS |
1 |
|
0
(0)| 00:00:01 |
|
6 |
TABLE ACCESS BY INDEX ROWID| PURCHASEORDER
|
1 |
72 |
1
(0)| 00:00:01 |
------------------------------------------------------------------------------------------------------Predicate Information (identified by operation id):
--------------------------------------------------4 - filter("SYS_NC00009$" IS NOT NULL AND "SYS_NC00011$"='717951002372')
5 - access("NESTED_TABLE_ID"="PURCHASEORDER"."SYS_NC0003400035$")

8-6 Oracle XML DB Developer's Guide

Analyzing and Optimizing XPath Queries using Execution Plans

The execution plan shows a full scan of ordered collection table lineitem_table.
This could be acceptable if there were only a few hundred documents in the
purchaseorder table, but it would be unacceptable if there were thousands or
millions of documents in the table.
To improve the performance of such a query, you can create an index that provides
direct access to pseudocolumn NESTED_TABLE_ID, given the value of attribute Id.
Unfortunately, Oracle XML DB does not allow indexes on collections to be created
using XPath expressions directly. To create the index, you must understand the
structure of the SQL object that is used to manage the LineItem elements. Given this
information, you can create the required index using conventional object-relational
SQL.
In this case, element LineItem is stored as an instance of object type lineitem_t.
Element Part is stored as an instance of SQL data type part_t. XML attribute Id is
mapped to object attribute part_number. Given this information, you can create a
composite index on attribute part_number and pseudocolumn NESTED_TABLE_ID, as
shown in Example 8–9. This index provides direct access to those purchase-order
documents that have LineItem elements that reference the required part.
Example 8–9 Creating an Index for Direct Access to an Ordered Collection Table
CREATE INDEX lineitem_part_index ON lineitem_table l (l.part.part_number, l.NESTED_TABLE_ID);

Guideline: Use XMLOptimizationCheck to determine why a query is not rewritten
If a query has not been optimized, you can use system variable
XMLOptimizationCheck to try to determine why.

See Also: "Diagnosing XQuery Optimization:
XMLOptimizationCheck" on page 5-35

XPath Rewrite for Structured Storage 8-7

Analyzing and Optimizing XPath Queries using Execution Plans

8-8 Oracle XML DB Developer's Guide

9
XML Schema Storage and Query: Advanced
This chapter describes advanced techniques for storing structured XML schema-based
XMLType objects.
See Also:
■

■

■

■

Chapter 7, "XML Schema Storage and Query: Basic" for basic
information about using XML Schema with Oracle XML DB
Chapter 8, "XPath Rewrite for Structured Storage" for
information about the optimization of XPath expressions in
Oracle XML DB
Chapter 10, "XML Schema Evolution" for information about
updating an XML schema after you have registered it with
Oracle XML DB
http://www.w3.org/TR/xmlschema-0/ for an
introduction to XML Schema

This chapter contains these topics:
■

Generating XML Schemas with DBMS_XMLSCHEMA.GENERATESCHEMA

■

Adding Unique Constraints to the Parent Element of an Attribute

■

Setting Annotation Attribute SQLInline to false for Out-Of-Line Storage

■

Storing Collections in Out-Of-Line Tables

■

Partitioning XMLType Tables and Columns Stored Object-Relationally

■

Fully Qualified XML Schema URLs

■

Mapping XML Fragments to Large Objects (LOBs)

■

complexType Extensions and Restrictions in Oracle XML DB

■

XML Schema: Working with Circular and Cyclical Dependencies

■

Support for Recursive Schemas

■

Loading and Retrieving Large Documents with Collections

Generating XML Schemas with DBMS_XMLSCHEMA.GENERATESCHEMA
An XML schema can be generated from an object-relational type automatically using a
default mapping. PL/SQL functions generateSchema and generateSchemas in
package DBMS_XMLSCHEMA take in a string that has the object type name and another
that has the Oracle XML DB XML schema.
XML Schema Storage and Query: Advanced

9-1

Generating XML Schemas with DBMS_XMLSCHEMA.GENERATESCHEMA

■

■

Function generateSchema returns an XMLType containing an XML schema. It
can optionally generate an XML schema for all types referenced by the given
object type or restricted only to the top-level types.
Function generateSchemas is similar, except that it returns an
XMLSequenceType value. This is a varray of XMLType instances, each of which is
an XML schema that corresponds to a different namespace. It also takes an
additional optional argument that specifies the root URL of the preferred XML
schema location:
http://xmlns.oracle.com/xdb/schemas/.xsd

Both generateSchema and generateSchemas return XML schemas that have
Oracle XML DB annotations.
Example 9–1 shows the definition of an object type, employee_t, and an invocation
of generateSchema that generates an XML schema for that object type.
Example 9–1 Generating an XML Schema with Function GENERATESCHEMA
CREATE TYPE employee_t AS OBJECT(empno NUMBER(10),
ename VARCHAR2(200),
salary NUMBER(10,2));
SELECT DBMS_XMLSCHEMA.generateSchema('T1', 'EMPLOYEE_T') FROM DUAL;
DBMS_XMLSCHEMA.GENERATESCHEMA('T1', 'EMPLOYEE_T')
-----------------------------------------------------------------------










The generated XML schema declares element EMPLOYEE_T and complex type
EMPLOYEE_TType. It uses annotations from namespace
http://xmlns.oracle.com/xdb.
See Also: "Creating XMLType Tables and Columns Based on XML
Schemas" on page 7-27

9-2 Oracle XML DB Developer's Guide

Adding Unique Constraints to the Parent Element of an Attribute

Adding Unique Constraints to the Parent Element of an Attribute
After creating an XMLType table based on an XML schema, how can you add a unique
constraint to the parent element of an attribute? You might, for example, want to create
a unique key based on an attribute of an element that repeats itself (a collection).
To create constraints on elements that can occur more than once, store the varray as an
ordered collection table (OCT). You can then create constraints on the OCT.
Example 9–2 shows an XML schema that lets attribute No of element 
appear more than once. The example shows how you can add a unique constraint to
ensure that the same phone number cannot be repeated within a given instance
document.
Example 9–2 Adding a Unique Constraint to the Parent Element of an Attribute
BEGIN DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'emp.xsd',
SCHEMADOC => '












',
LOCAL
=> FALSE,
GENTYPES => FALSE);
END;
/
PL/SQL procedure successfully completed.
CREATE TABLE emp_tab OF XMLType
XMLSCHEMA "emp.xsd" ELEMENT "Employee"
VARRAY XMLDATA."PhoneNumber" STORE AS TABLE phone_tab;
Table created.
ALTER TABLE phone_tab ADD UNIQUE (NESTED_TABLE_ID, "No");
Table altered.
INSERT INTO emp_tab
VALUES(XMLType('
1234


').createSchemaBasedXML('emp.xsd'));
1 row created.
INSERT INTO emp_tab
VALUES(XMLType('
XML Schema Storage and Query: Advanced

9-3

Setting Annotation Attribute SQLInline to false for Out-Of-Line Storage

3456


').createSchemaBasedXML('emp.xsd'));

This returns the expected result:
*
ERROR at line 1:
ORA-00001: unique constraint (SCOTT.SYS_C002136) violated

The constraint in this example applies to each collection, and not across all instances.
This is achieved by creating a concatenated index with the collection id column. To
apply the constraint across all collections of all instance documents, omit the collection
id column.
You can create only a functional constraint as a unique or
foreign key constraint on XMLType data stored as binary XML.

Note:

Setting Annotation Attribute SQLInline to false for Out-Of-Line Storage
By default, a child XML element is mapped to an embedded SQL object attribute,
when XMLType data is stored object-relationally. However, there are scenarios where
out-of-line storage offers better performance. In such cases, set XML schema
annotation (attribute) xdb:SQLInline to false, so Oracle XML DB generates a SQL
object type with an embedded REF attribute. The REF points to another XMLType
instance that is stored out of line and that corresponds to the XML fragment. Default
XMLType tables are also created, to store the out-of-line fragments.
Figure 9–1 illustrates the mapping of complexType to SQL for out-of-line storage.
Figure 9–1 Mapping complexType to SQL for Out-Of-Line Storage
.
.
.

.
.
.

Employee_tab of type OBJ_T2
Name Age Addr REF XMLType

This XML fragment is
stored out-of-line

Addr_tab of type OBJ_T1
Street City

REF points
to another
XMLType
instance

XMLType table

Starting with Oracle Database 11g Release 2 (11.2.0.2), you can
create only one XMLType table that uses an XML schema that results in
an out-of-line table. An error is raised if you try to create a
second table that uses the same XML schema.

Note:

9-4 Oracle XML DB Developer's Guide

Setting Annotation Attribute SQLInline to false for Out-Of-Line Storage

Example 9–3 Setting SQLInline to False for Out-Of-Line Storage
DECLARE
doc VARCHAR2(3000) :=
'















';
BEGIN
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL
=> 'emp.xsd',
SCHEMADOC
=> doc,
ENABLE_HIERARCHY => DBMS_XMLSCHEMA.ENABLE_HIERARCHY_NONE);
END;
/

In Example 9–3, attribute xdb:SQLInline of element Addr has value false. The
resulting SQL object type, obj_t2, has an XMLType column with an embedded REF
object attribute. The REF attribute points to an XMLType instance of SQL object type
obj_t1 in table addr_tab. Table addr_tab is stored out of line. It has columns
street and city.
When registering this XML schema, Oracle XML DB generates the XMLType tables and
types shown in Example 9–4.
Example 9–4 Generated XMLType Tables and Types
DESCRIBE emp_tab
Name
Null?
Type
----------------------------- ----------------------------------------------------------------TABLE of SYS.XMLTYPE(XMLSchema "emp.xsd" Element "Employee") STORAGE
Object-relational TYPE "EMP_T"
DESCRIBE addr_tab
Name
Null?
Type
----------------------------- --------------------------------------------------------------TABLE of SYS.XMLTYPE(XMLSchema "emp.xsd" Element "Addr") STORAGE Object-relational
TYPE "ADDR_T"
DESCRIBE emp_t

XML Schema Storage and Query: Advanced

9-5

Setting Annotation Attribute SQLInline to false for Out-Of-Line Storage

emp_t is NOT FINAL
Name
Null?
----------------------------- -------SYS_XDBPD$
Name
Age
Addr

Type
-------------------XDB.XDB$RAW_LIST_T
VARCHAR2(4000 CHAR)
NUMBER
REF OF XMLTYPE

DESCRIBE addr_t
Name
Null?
----------------------------- -------SYS_XDBPD$
Street
City

Type
-------------------XDB.XDB$RAW_LIST_T
VARCHAR2(4000 CHAR)
VARCHAR2(4000 CHAR)

Table emp_tab holds all of the employee information, and it contains an object
reference that points to the address information that is stored out of line, in table
addr_tab.
An advantage of this model is that it lets you query the out-of-line table (addr_tab)
directly, to look up address information. Example 9–5 illustrates querying table addr_
tab directly to obtain the distinct city information for all employees.
Example 9–5 Querying an Out-Of-Line Table
INSERT INTO emp_tab
VALUES
(XMLType('
Abe Bee
22

A Street
San Francisco

'));
INSERT INTO emp_tab
VALUES
(XMLType('
Cecilia Dee
23

C Street
Redwood City

'));
. . .
SELECT DISTINCT XMLCast(XMLQuery('/Addr/City' PASSING OBJECT_VALUE AS "."
RETURNING CONTENT)
AS VARCHAR2(20))
FROM addr_tab;
CITY

9-6 Oracle XML DB Developer's Guide

Setting Annotation Attribute SQLInline to false for Out-Of-Line Storage

------------Redwood City
San Francisco

The disadvantage of this storage model is that, in order to obtain the entire Employee
element, you must access an additional table for the address.

XPath Rewrite for Out-Of-Line Tables
XPath expressions that involve elements stored out of line can be rewritten. The
rewritten query involves a join with the out-of-line table. Example 9–6 shows such a
query.
Example 9–6 XPath Rewrite for an Out-Of-Line Table
SELECT XMLCast(XMLQuery('declare namespace x = "http://www.oracle.com/emp.xsd"; (: :)
/x:Employee/Name' PASSING OBJECT_VALUE RETURNING CONTENT)
AS VARCHAR2(20))
FROM emp_tab
WHERE XMLExists('declare namespace x = "http://www.oracle.com/emp.xsd"; (: :)
/x:Employee/Addr[City="San Francisco"]' PASSING OBJECT_VALUE);
XMLCAST(XMLQUERY(...
-------------------Abe Bee
Eve Fong
George Hu
Iris Jones
Karl Luomo
Marina Namur
Omar Pinano
Quincy Roberts
8 rows selected.

The XQuery expression here is rewritten to a SQL EXISTS subquery that queries table
addr_tab, joining it with table emp_tab using the object identifier column in addr_
tab. The optimizer uses full table scans of tables emp_tab and addr_tab. If there are
many entries in the addr_tab, then you can try to make this query more efficient by
creating an index on the city, as shown in Example 9–7. An explain-plan fragment for
the same query as in Example 9–6 shows that the city index is picked up.
Example 9–7 Using an Index with an Out-Of-Line Table
CREATE INDEX addr_city_idx
ON addr_tab (extractValue(OBJECT_VALUE, '/Addr/City'));
|
|*
|

2 |
3 |
4 |

TABLE ACCESS BY INDEX ROWID| ADDR_TAB
|
INDEX RANGE SCAN
| ADDR_CITY_IDX |
TABLE ACCESS FULL
| EMP_TAB
|

1 | 2012 |
1 |
|
16 | 32464 |

1
1
2

(0)| 00:00:01 |
(0)| 00:00:01 |
(0)| 00:00:01 |

XML Schema Storage and Query: Advanced

9-7

Storing Collections in Out-Of-Line Tables

When gathering statistics for the optimizer on an XMLType
table that is stored object-relationally, Oracle recommends that you
gather statistics on all of the tables defined by the XML schema, that is,
all of the tables in USER_XML_TABLES. You can use procedure DBMS_
STATS.gather_schema_stats to do this, or use DBMS_
STATS.gather_table_stats on each such table. This informs the
optimizer about all of the dependent tables that are used to store the
XMLType data.

Note:

See Also:

Chapter 8, "XPath Rewrite for Structured Storage"

Storing Collections in Out-Of-Line Tables
You can also map collection items to be stored out of line. In this case, instead of a
single REF column, the parent element contains a varray of REF values that point to
the collection members. For example, suppose that there is a list of addresses for each
employee and that list is mapped to out-of-line storage, as shown in Example 9–8.
Example 9–8 Storing a Collection Out of Line
DECLARE
doc VARCHAR2(3000) :=
'















';
BEGIN
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL
=> 'emp.xsd',
SCHEMADOC
=> doc,
ENABLE_HIERARCHY => DBMS_XMLSCHEMA.ENABLE_HIERARCHY_NONE);
END;
/

During registration of this XML schema, Oracle XML DB generates tables emp_tab
and addr_tab and types emp_t and addr_t, just as in Example 9–3. However, this
time, type emp_t contains a varray of REF values that point to addresses, instead of a
single REF attribute, as shown in Example 9–9.

9-8 Oracle XML DB Developer's Guide

Storing Collections in Out-Of-Line Tables

Example 9–9 Generated Out-Of-Line Collection Type
DESCRIBE emp_t
emp_t is NOT FINAL
Name
Null?
-------------------------------------- -------SYS_XDBPD$
Name
Age
Addr

Type
-------------------------XDB.XDB$RAW_LIST_T
VARCHAR2(4000 CHAR)
NUMBER
XDB.XDB$XMLTYPE_REF_LIST_T

By default, XML schema attribute storeVarrayAsTable has value true, which
means that the varray of REF values is stored out of line, in an intermediate table.
That is, in addition to creating the tables and types just mentioned, XML schema
registration also creates the intermediate table that stores the list of REF values. This
table has a system-generated name, but you can rename it. That can be useful, for
example, in order to create an index on it.
Example 9–10

Renaming an Intermediate Table of REF Values

DECLARE
gen_name VARCHAR2 (4000);
BEGIN
SELECT TABLE_NAME INTO gen_name FROM USER_NESTED_TABLES
WHERE PARENT_TABLE_NAME = 'EMP_TAB';
EXECUTE IMMEDIATE 'RENAME "' || gen_name || '"TO emp_tab_reflist';
END;
/
DESCRIBE emp_tab_reflist
Name
Null?
Type
----------------------- -------- ---------------COLUMN_VALUE
REF OF XMLTYPE

Example 9–11 shows a query that selects the names of all San Francisco-based
employees and the streets in which they live. The example queries the address table on
element City, and joins back with the employee table. The explain-plan fragment
shown indicates a join between tables emp_tab_reflist and emp_tab.
Example 9–11

XPath Rewrite for an Out-Of-Line Collection

SELECT em.name, ad.street
FROM emp_tab,
XMLTable(XMLNAMESPACES ('http://www.oracle.com/emp.xsd' AS "x"),
'/x:Employee' PASSING OBJECT_VALUE
COLUMNS name
VARCHAR2(20) PATH 'Name') em,
XMLTable(XMLNAMESPACES ('http://www.oracle.com/emp.xsd' AS "x"),
'/x:Employee/Addr' PASSING OBJECT_VALUE
COLUMNS street VARCHAR2(20) PATH 'Street',
city
VARCHAR2(20) PATH 'City') ad
WHERE ad.city = 'San Francisco';
NAME
-------------------Abe Bee
Eve Fong
George Hu
Iris Jones
Karl Luomo
Marina Namur

STREET
-------------------A Street
E Street
G Street
I Street
K Street
M Street

XML Schema Storage and Query: Advanced

9-9

Partitioning XMLType Tables and Columns Stored Object-Relationally

Omar Pinano
Quincy Roberts

O Street
Q Street

8 rows selected.
|
|
|*

4 |
5 |
6 |

TABLE ACCESS FULL
| EMP_TAB_REFLIST |
TABLE ACCESS BY INDEX ROWID| EMP_TAB
|
INDEX UNIQUE SCAN
| SYS_C005567
|

32 |
1 |
1 |

640 |
29 |
|

2
1
0

(0)| 00:00:01 |
(0)| 00:00:01 |
(0)| 00:00:01 |

To improve performance you can create an index on the REF values in the
intermediate table, emp_tab_reflist. This lets Oracle XML DB query the address
table, obtain an object reference (REF) to the relevant row, join it with the intermediate
table storing the list of REF values, and join that table back with the employee table.
You can create an index on REF values only if the REF is scoped or has a referential
constraint. A scoped REF column stores pointers only to objects in a particular table.
The REF values in table emp_tab_reflist point only to objects in table addr_tab,
so you can create a scope constraint and an index on the REF column, as shown in
Example 9–12.
Example 9–12

XPath Rewrite for an Out-Of-Line Collection, with Index on REFs

ALTER TABLE emp_tab_reflist ADD SCOPE FOR (COLUMN_VALUE) IS addr_tab;
CREATE INDEX reflist_idx ON emp_tab_reflist (COLUMN_VALUE);

The explain-plan fragment for the same query as in Example 9–11 shows that index
reflist_idx is picked up.
|
|*
|
|*

4
5
6
7

|
|
|
|

TABLE ACCESS BY INDEX ROWID|
INDEX RANGE SCAN
|
TABLE ACCESS BY INDEX ROWID |
INDEX UNIQUE SCAN
|

EMP_TAB_REFLIST
REFLIST_IDX
EMP_TAB
SYS_C005567

|
|
|
|

1 |
1 |
|
1 |

20 |
|
|
|

1
0
0

(0)| 00:00:01 |
(0)| 00:00:01 |
|
|
(0)| 00:00:01 |

In cases where the more selective predicates in the query are on the employee table,
you might want to set XML schema attribute storeVarrayAsTable to false, in
order to store the varray of REF values in line in table emp_tab. Storing the varray in
line effectively forces any query involving the two tables emp_tab and addr_tab to
always be driven from emp_tab. There is then no way to efficiently join back from the
address table. This approach is inappropriate when the number of employees is large,
because it involves a full table scan of table emp_tab, which can be expensive.

Partitioning XMLType Tables and Columns Stored Object-Relationally
This section is about XML data that is stored using structured storage, that is,
object-relationally.
When you partition an XMLType table or a table with an XMLType column using list,
range, or hash partitioning, any ordered collection tables (OCTs) or out-of-line tables
within the data are automatically partitioned accordingly, by default.
This equipartitioning means that the partitioning of an OCT or an out-of-line table
follows the partitioning scheme of its parent (base) table. There is a corresponding
child-table partition for each partition of the base table. A child element is stored in the
child-table partition that corresponds to the base-table partition of its parent element.
Storage attributes for a base table partition are, by default, also used for the
corresponding child-table partitions. You can override these storage attributes for a
given child-table partition.

9-10 Oracle XML DB Developer's Guide

Partitioning XMLType Tables and Columns Stored Object-Relationally

Similarly, by default, the name of an OCT partition is the same as its base (parent)
table, but you can override this behavior by specifying the name to use. The name of
an out-of-line table partition is always the same as the partition of its parent-table
(which could be a base table or an OCT).
Note:
■

■

Equipartitioning of XMLType data stored object-relationally is not
available in releases prior to Oracle Database 11g Release 1 (11.1).
Equipartitioning of XMLType data that is stored out of line is not
available in releases prior to Oracle Database 11g Release 2
(11.2.0.2). Starting with that release, out-of-line tables are not
shared: You cannot create two top-level tables that are based on
the same XML schema, if that schema specifies an out-of-line
table.

You can prevent partitioning of OCTs by specifying the keyword
GLOBAL in a CREATE TABLE statement. (Starting with Oracle
Database 11g Release 1 (11.1), the default behavior uses keyword
LOCAL). For information about converting a non-partitioned collection
table to a partitioned collection table, see Oracle Database VLDB and
Partitioning Guide.
You can prevent partitioning of out-of-line tables, and thus allow
out-of-line sharing, by turning on event 31178 with level 0x200:
ALTER SESSION SET EVENTS '31178 TRACE NAME CONTEXT FOREVER, LEVEL
0x200'

See Also:
■

■

"Controlling How Collections Are Stored for Object-Relational
XMLType Storage" on page 3-19 for information about OCTs
Oracle Database SQL Language Reference for information about
creating tables with partitions using keywords GLOBAL and
LOCAL

Examples of Partitioning XMLType Data
You can specify partitioning information for an XMLType base table in two ways:
■

■

During XML schema registration, using XML Schema annotation
xdb:tableProps
During table creation using CREATE TABLE

Example 9–13 and Example 9–14 illustrate this. These two examples have exactly the
same effect. They partition the base purchaseorder table using the Reference
element to specify ranges. They equipartition the child table of line items with respect
to the base table.
Example 9–13 shows element PurchaseOrder from the purchase-order XML schema,
annotated to partition the base table and its child table of line items.
Example 9–13

Specifying Partitioning Information During XML Schema Registration



Example 9–14 specifies the same partitioning as in Example 9–13, but it does so during
the creation of the base table purchaseorder.
Example 9–14

Specifying Partitioning Information During Table Creation

CREATE TABLE purchaseorder OF XMLType
XMLSCHEMA "http://localhost:8080/source/schemas/poSource/xsd/purchaseOrder.xsd"
ELEMENT "PurchaseOrder"
VARRAY "XMLDATA"."LINEITEMS"."LINEITEM" STORE AS TABLE lineitem_table
((PRIMARY KEY (NESTED_TABLE_ID, SYS_NC_ARRAY_INDEX$)))
PARTITION BY RANGE (XMLDATA.Reference)
(PARTITION p1 VALUES LESS THAN (1000)
VARRAY "XMLDATA"."LINEITEMS"."LINEITEM" STORE AS TABLE lineitem_p1
(STORAGE (MINEXTENTS 13)),
PARTITION p2 VALUES LESS THAN (2000)
VARRAY "XMLDATA"."LINEITEMS"."LINEITEM" STORE AS TABLE lineitem_p2
(STORAGE (MINEXTENTS 13)));

Example 9–13 and Example 9–14 also show how you can specify object storage options
for the individual child-table partitions. In this case, the STORAGE clauses specify that
extents of size 14M are to be allocated initially for each of the child-table partitions.
See Also:
■

■

■

■

"Annotated Purchase-Order XML Schema, purchaseOrder.xsd" on
page A-30
Example 3–13, "Creating an XMLType Table that Conforms to an
XML Schema" on page 3-28
Oracle Database Object-Relational Developer's Guide for more
information about partitioning object-relational data
Oracle Database VLDB and Partitioning Guide for more information
about partitioning

Partition Maintenance
You need not define or maintain child-table partitions manually. When you perform
partition maintenance on the base (parent) table, corresponding maintenance is
automatically performed on the child tables as well.
There are a few exceptions to the general rule that you perform partition maintenance
only on the base table. In the following cases you perform maintenance on a child
table:
■

Modify the default physical storage attributes of a collection partition

■

Modify the physical storage attributes of a collection partition

9-12 Oracle XML DB Developer's Guide

Fully Qualified XML Schema URLs

■

■

Move a collection partition to a different segment, possibly in a different
tablespace
Rename a collection partition

For example, if you change the tablespace of a base table, that change is not cascaded
to its child-table partitions. You must manually use ALTER TABLE MODIFY
PARTITION on the child-table partitions to change their tablespace.
Other than those exceptional operations, you perform all partition maintenance on the
base table only. This includes operations such as adding, dropping, and splitting a
partition.
Online partition redefinition is also supported for child tables. You can copy
unpartitioned child tables to partitioned child tables during online redefinition of a
base table. You typically specify parameter values copy_indexes => 0 and copy_
constraints => false for PL/SQL procedure DBMS_REDEFINITION.copy_
table_dependents, to protect the indexes and constraints of the newly defined
child tables.
See Also:
■

■

Oracle Database SQL Language Reference for information about SQL
statement ALTER TABLE
Oracle Database PL/SQL Packages and Types Reference for
information about online partition redefinition using PL/SQL
package DBMS_REDEFINITION

Fully Qualified XML Schema URLs
By default, XML schema URLs are referenced within the scope of the current database
user. XML schema URLs are first resolved as the names of local XML schemas owned
by the current user.
■

■

If there are no such XML schemas, then they are resolved as names of global XML
schemas.
If there are no global XML schemas either, then Oracle XML DB raises an error.

To permit explicit reference to particular XML schemas, Oracle XML DB supports the
notion of fully qualified XML schema URLs. The name of the database user owning the
XML schema is specified as part of the XML schema URL. Fully qualified XML schema
URLs belong to the Oracle XML DB namespace:
http://xmlns.oracle.com/xdb/schemas//

For example, suppose there is a registered global XML schema with the URL
http://www.example.com/po.xsd, and user QUINE has a local registered XML
schema with the same URL. Another user can reference the schema owned by QUINE
as follows using this fully qualified XML Schema URL:
http://xmlns.oracle.com/xdb/schemas/QUINE/www.example.com/po.xsd

The fully qualified URL for the global XML schema is:
http://xmlns.oracle.com/xdb/schemas/PUBLIC/www.example.com/po.xsd

See Also:

"Local and Global XML Schemas" on page 7-14

XML Schema Storage and Query: Advanced

9-13

Mapping XML Fragments to Large Objects (LOBs)

Mapping XML Fragments to Large Objects (LOBs)
You can specify the SQL data type to use for a complex element as being CLOB or
BLOB. In Figure 9–2, for example, an entire XML fragment is stored in a LOB attribute.
This is useful when parts of an XML document are typically retrieved and stored as
whole, and are seldom queried. By storing XML fragments as LOBs, you can save on
parsing, decomposition, and recomposition overheads.
In Example 9–15, the XML schema defines element Addr using the annotation
SQLType = "CLOB":
Example 9–15
LOBs

Oracle XML DB XML Schema: Mapping complexType XML Fragments to

DECLARE
doc VARCHAR2(3000) :=
'














';
BEGIN
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'http://www.oracle.com/PO.xsd',
SCHEMADOC => doc);
END;

When registering this XML schema, Oracle XML DB generates the following types and
XMLType tables:
CREATE TYPE obj_t AS OBJECT(SYS_XDBPD$ XDB.XDB$RAW_LIST_T,
Name VARCHAR2(4000),
Age NUMBER,
Addr CLOB);

9-14 Oracle XML DB Developer's Guide

complexType Extensions and Restrictions in Oracle XML DB

Figure 9–2 Mapping complexType XML Fragments to Character Large Objects (CLOB)
.
.
.

.
.
.

Employee_tab of type OBJ_T
Name Age Addr
CLOB

Street and
city are stored
in the CLOB

complexType Extensions and Restrictions in Oracle XML DB
In XML Schema, complexType values are declared based on complexContent and
simpleContent.
■

simpleContent is declared as an extension of simpleType.

■

complexContent is declared as one of the following:
■

Base type

■

complexType extension

■

complexType restriction

This section describes the Oracle XML DB extensions and restrictions to
complexType.

complexType Declarations in XML Schema: Handling Inheritance
For complexType, Oracle XML DB handles inheritance in the XML schema as
follows:
■

■

For complex types declared to extend other complex types, the SQL type
corresponding to the base type is specified as the supertype for the current SQL
type. Only the additional attributes and elements declared in the sub-complextype
are added as attributes to the sub-object-type.
For complex types declared to restrict other complex types, the SQL type for the
sub-complex type is set to be the same as the SQL type for its base type. This is
because SQL does not support restriction of object types through the inheritance
mechanism. Any constraints are imposed by the restriction in XML schema.

Example 9–16 shows the registration of an XML schema that defines a base
complexType Address and two extensions USAddress and IntlAddress.
Example 9–16 XML Schema Inheritance: complexContent as an Extension of
complexTypes
DECLARE
doc VARCHAR2(3000) :=
'


XML Schema Storage and Query: Advanced

9-15

complexType Extensions and Restrictions in Oracle XML DB
























';
BEGIN
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'http://www.oracle.com/PO.xsd',
SCHAMEDOC => doc);
END;

Type intladdr_t is created as a final type because the
corresponding complexType specifies the "final" attribute. By
default, all complexTypes can be extended and restricted by other
types, so all SQL object types are created as types that are not final.
Note:

CREATE TYPE addr_t AS OBJECT(SYS_XDBPD$ XDB.XDB$RAW_LIST_T,
"street" VARCHAR2(4000),
"city" VARCHAR2(4000)) NOT FINAL;
CREATE TYPE usaddr_t UNDER addr_t ("zip" VARCHAR2(4000)) NOT FINAL;
CREATE TYPE intladdr_t UNDER addr_t ("country" VARCHAR2(4000)) FINAL;

Example 9–17 shows the registration of an XML schema that defines a base
complexType Address and a restricted type LocalAddress that prohibits the
specification of country attribute.
Example 9–17

Inheritance in XML Schema: Restrictions in complexTypes

DECLARE
doc varchar2(3000) :=
'







9-16 Oracle XML DB Developer's Guide

complexType Extensions and Restrictions in Oracle XML DB















';
BEGIN
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'http://www.oracle.com/PO.xsd',
SCHEMADOC => doc);
END;

Because SQL inheritance does not support a notion of restriction, the SQL data type
corresponding to a restricted complexType is a empty subtype of the parent object
type. For the XML schema of Example 9–17, Oracle XML DB generates the following
SQL types:
CREATE TYPE addr_t AS OBJECT (SYS_XDBPD$
"street"
"city"
"zip"
"country"
CREATE TYPE usaddr_t UNDER addr_t;

XDB.XDB$RAW_LIST_T,
VARCHAR2(4000),
VARCHAR2(4000),
VARCHAR2(4000),
VARCHAR2(4000)) NOT FINAL;

Mapping complexType: simpleContent to Object Types
A complex type based on a simpleContent declaration is mapped to an object type
with attributes corresponding to the XML attributes and an extra SYS_XDBBODY$
attribute corresponding to the body value. The data type of the body attribute is based
on simpleType which defines the body type.
Example 9–18

XML Schema complexType: Mapping complexType to simpleContent

DECLARE
doc VARCHAR2(3000) :=
'






';
BEGIN
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'http://www.oracle.com/emp.xsd',
SCHEMADOC => doc);

XML Schema Storage and Query: Advanced

9-17

XML Schema: Working with Circular and Cyclical Dependencies

END;

For the XML schema of Example 9–18, Oracle XML DB generates the following type:
CREATE TYPE obj_t AS OBJECT(SYS_XDBPD$ XDB.XDB$RAW_LIST_T,
SYS_XDBBODY$ VARCHAR2(4000));

Mapping complexType: any and anyAttribute
Oracle XML DB maps the element declaration, any, and the attribute declaration,
anyAttribute, to VARCHAR2 attributes (or optionally to Large Objects (LOBs)) in the
created object type. The object attribute stores the text of the XML fragment that
matches the any declaration.
■

■

The namespace attribute can be used to restrict the contents so that they belong to
a specified namespace.
The processContents attribute within the any element declaration, indicates
the level of validation required for the contents matching the any declaration.

The code in Example 9–19 declares an any element and maps it to the column SYS_
XDBANY$, in object type obj_t. It also declares that attribute processContents
does not validate contents that match the any declaration.
Example 9–19

XML Schema: Mapping complexType to any/anyAttribute

DECLARE
doc VARCHAR2(3000) :=
'







';
BEGIN
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'http://www.oracle.com/emp.xsd',
SCHEMADOC => doc);
END;

For the XML schema of Example 9–19, Oracle XML DB generates the following type:
CREATE TYPE obj_t AS OBJECT(SYS_XDBPD$ XDB.XDB$RAW_LIST_T,
Name VARCHAR2(4000),
Age NUMBER,
SYS_XDBANY$ VARCHAR2(4000));

XML Schema: Working with Circular and Cyclical Dependencies
The W3C XML Schema Recommendation lets complexTypes and global elements
contain recursive references. For example, a complexType definition can contain an
element based on that same complexType, or a global element can contain a reference
to itself. In both cases the reference can be direct or indirect. This kind of structure

9-18 Oracle XML DB Developer's Guide

XML Schema: Working with Circular and Cyclical Dependencies

allows for instance documents where the element in question can appear an infinite
number of times in a recursive hierarchy.
Example 9–20

An XML Schema with Circular Dependency


















The XML schema in Example 9–20 includes a circular dependency. The complexType
personType consists of a personName attribute and a collection of descendant
elements. The descendant element is defined as being of type personType.

For Circular XML Schema Dependencies Set Parameter GENTABLES to TRUE
Oracle XML DB supports XML schemas that define this kind of structure. It does this
by detecting the cycles, breaking them, and storing the recursive elements as rows in a
separate XMLType table that is created during XML schema registration.
Consequently, it is important to ensure that parameter GENTABLES is set to TRUE
when registering an XML schema that defines this kind of structure. The name of the
table used to store the recursive elements can be specified by adding an
xdb:defaultTable annotation to the XML schema.

complexType Declarations XML Schema: Handling Cycles
SQL object types do not allow cycles. Cycles in an XML schema are broken while
generating the object types, by introducing a REF attribute at the point where the cycle
would be completed. Thus, part of the data is stored out of line, but it is still retrieved
as part of the parent XML document.
Starting with Oracle Database 11g Release 2 (11.2.0.2), you can
create only one XMLType table that uses an XML schema that results in
an out-of-line table. An error is raised if you try to create a
second table that uses the same XML schema.

Note:

XML schemas permit cycling between definitions of complex types. Figure 9–3 shows
this, where the definition of complex type CT1 can reference another complex type
CT2, whereas the definition of CT2 references the first type CT1.

XML Schema Storage and Query: Advanced

9-19

XML Schema: Working with Circular and Cyclical Dependencies

XML schemas permit cycles among definitions of complex types. Example 9–21 creates
a cycle of length two:
Example 9–21

XML Schema: Cycling Between complexTypes

DECLARE
doc VARCHAR2(3000) :=
'












';
BEGIN
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'http://www.oracle.com/emp.xsd',
SCHEMADOC => doc);
END;

SQL types do not allow cycles in type definitions. However, they do support weak
cycles, that is, cycles involving REF (reference) object attributes. Cyclic XML schema
definitions are mapped to SQL object types in such a way that cycles are avoided by
forcing SQLInline = "false" at the appropriate points. This creates a weak SQL
cycle.
For the XML schema of Example 9–21, Oracle XML DB generates the following types:
CREATE TYPE ct1 AS OBJECT (SYS_XDBPD$
"e1"
"e2"
CREATE TYPE ct2 AS OBJECT (SYS_XDBPD$
"e1"
"e2"

XDB.XDB$RAW_LIST_T,
VARCHAR2(4000),
REF XMLType) NOT FINAL;
XDB.XDB$RAW_LIST_T,
VARCHAR2(4000),
CT1) NOT FINAL;

Figure 9–3 Cross Referencing Between Different complexTypes in the Same XML
Schema
XML schema, emp. xsd

.
.
.

.
.
.


.
.
.

.
.
.

Another example of a cyclic complex type involves the declaration of the complex type
that refers to itself. In Example 9–22, type SectionT does this.

9-20 Oracle XML DB Developer's Guide

XML Schema: Working with Circular and Cyclical Dependencies

Example 9–22

XML Schema: Cycling Between complexTypes, Self-Reference

DECLARE
doc VARCHAR2(3000) :=
'









';
BEGIN
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'http://www.oracle.com/section.xsd',
SCHEMADOC => doc);
END;

For the XML schema of Example 9–22, Oracle XML DB generates the following types:
CREATE TYPE body_coll AS VARRAY(32767) OF VARCHAR2(4000);
CREATE TYPE section_t AS OBJECT (SYS_XDBPD$ XDB.XDB$RAW_LIST_T,
"title"
VARCHAR2(4000),
"body"
BODY_COLL,
"section"
XDB.XDB$REF_LIST_T) NOT FINAL;

In Example 9–22, object attribute section is declared as a
varray of REF references to XMLType instances. Because there can
be more than one occurrence of embedded sections, the attribute is
a varray. It is a varray of REF references to XMLType instances, to
avoid forming a cycle of SQL objects.
Note:

How a complexType Can Reference Itself
Assume that your XML schema, identified by "http://www.oracle.com/PO.xsd",
has been registered. An XMLType table, purchaseorder, can then be created to store
instances conforming to element PurchaseOrder of this XML schema, in an
object-relational format:
CREATE TABLE purchaseorder OF XMLType
ELEMENT "http://www.oracle.com/PO.xsd#PurchaseOrder";

Figure 9–4 illustrates schematically how a complexType can reference itself.

XML Schema Storage and Query: Advanced

9-21

XML Schema: Working with Circular and Cyclical Dependencies

Figure 9–4 Self-Referencing Complex Type within an XML Schema
XML schema, emp. xsd

.
.
.

.
.
.

See Also: "Cyclical References Among XML Schemas" on
page 9-22

Hidden columns are created that correspond to the object type to which the
PurchaseOrder element has been mapped. In addition, an XMLEXTRA object column
is created, to store top-level instance data such as namespace declarations. XMLEXTRA
is reserved for internal use.

Cyclical References Among XML Schemas
XML schemas can depend on each other in such a way that they cannot be registered
one after the other in the usual manner. Illustrations of such XML schemas follow in
Figure 9–5.
In the top half of the illustration, an example of indirect cyclical references between
three XML schemas is shown.
In the bottom half of the illustration, an example of cyclical dependencies between two
XML schemas is shown. The details of this simpler example are presented first.
Figure 9–5 Cyclical References Between XML Schemas
XML schema 1, S1

XML schema 2, S2
References

S3

S1

References

XML schema 3, S3
References
S2

OR

XML schema 1, xm40

References

XML schema 2, xm40a

References
xm40a

9-22 Oracle XML DB Developer's Guide

xm40

XML Schema: Working with Circular and Cyclical Dependencies

An XML schema that includes another XML schema cannot be created if the included
XML schema does not exist. The registration of XML schema xm40.xsd in
Example 9–23 fails, if xm40a.xsd does not exist.
Example 9–23

An XML Schema that Includes a Non-Existent XML Schema

BEGIN DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'xm40.xsd',
SCHEMADOC => '










',
LOCAL
=> TRUE,
GENTYPES => TRUE,
GENTABLES => TRUE);
END;
/

XML schema xm40.xsd can, however, be created if you specify option FORCE =>
TRUE, as in Example 9–24:
Example 9–24

Using the FORCE Option to Register XML Schema xm40.xsd

BEGIN DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'xm40.xsd',
SCHEMADOC => '










',
LOCAL
=> TRUE,
GENTYPES => TRUE,
GENTABLES => TRUE,
FORCE
=> TRUE);
END;
/

However, an attempt to use XML schema xm40.xsd, as in Example 9–25, fails.

XML Schema Storage and Query: Advanced

9-23

Support for Recursive Schemas

Example 9–25

Trying to Create a Table Using a Cyclic XML Schema

CREATE TABLE foo OF XMLType XMLSCHEMA "xm40.xsd" ELEMENT "Emp";

If you register xm40a.xsd using the FORCE option, as in Example 9–26, then both
XML schemas can be used, as shown by the CREATE TABLE statements.
Example 9–26

Using the FORCE Option to Register XML Schema xm40a.xsd

BEGIN DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'xm40a.xsd',
SCHEMADOC => '











',
LOCAL
=> TRUE,
GENTYPES => TRUE,
GENTABLES => TRUE,
FORCE
=> TRUE);
END;
/
CREATE TABLE foo OF XMLType XMLSCHEMA "xm40.xsd" ELEMENT "Emp";
CREATE TABLE foo2 OF XMLType XMLSCHEMA "xm40a.xsd" ELEMENT "Comp";

Thus, to register these XML schemas, which depend on each other, you must use the
FORCE parameter in DBMS_XMLSCHEMA.registerSchema for each schema, as
follows:
1.

Register xm40.xsd with FORCE mode set to TRUE:
DBMS_XMLSCHEMA.registerSchema("xm40.xsd", " TRUE)

At this point, xm40.xsd cannot be used.
2.

Register xm40a.xsd in FORCE mode set to TRUE:
DBMS_XMLSCHEMA.registerSchema("xm40a.xsd", " TRUE)

The second operation automatically compiles xm40.xsd and makes both XML
schemas usable.

Support for Recursive Schemas
Storing a REF to a recursive structure that is in an out-of-line table has the
disadvantage that XPath queries against such documents cannot easily be rewritten,
because it is not known at compile time how deep the structure might be. To enable
rewrite of such XPath queries, a DOCID column is used to store a pointer back to the
root document in any recursive structure, enabling some queries to use the out-of-line
tables directly and join back using this column.
9-24 Oracle XML DB Developer's Guide

Support for Recursive Schemas

Example 9–27 shows a recursive XML schema.
Example 9–27

Recursive XML Schema




















A document-correlated recursive query is a query using a SQL function that accepts
an XPath or XQuery expression and an XMLType instance, where that XPath or
XQuery expression contains '//'. A document-correlated recursive query can be
rewritten if it can be determined at query compilation time that both of the following
conditions are met:
■

■

All fragments of the XMLType instance that are targeted by the XPath or XQuery
expression reside in a single out-of-line table.
No other fragments of the XMLType instance reside in the same out-of-line table.

The rewritten query is a join with the out-of-line table, based on the DOCID column.
Other queries with '//' can also be rewritten. For example, if there are several
address elements, all of the same type, in different sections of a schema, and you
often query all address elements with '//', not caring about their specific location in
the document, rewrite can occur.
During schema registration, an additional DOCID column is generated for out-of-line
XMLType tables This column stores the OID (Object Identifier Values) of the document,
that is, the root element. This column is automatically populated when data is inserted
in the tables. You can export tables containing DOCID columns and import them later.

Sharing defaultTable Among Common Out-Of-Line Elements
The out-of-line elements of the same qualified name (namespace and local name) and
same type are stored in the same default table. As a special case, you can store the root
element of a cyclic element structure out of line also, and in the same table as the
sub-elements (if the root element is stored out of line also).
Both of the elements sharing the default table must be out-of-line elements, that is, the
default table for an out-of-line element cannot be the same as the table for a top-level
element. To do this, specify xdb:SQLInline = "false" for both elements and
specify an explicit xdb:defaultTable attribute having the same value in both
elements.

XML Schema Storage and Query: Advanced

9-25

Support for Recursive Schemas

Example 9–28 shows an XML schema with an out-of-line table that is stored in
ABCSECTIONTAB.
Example 9–28

Out-of-line Table




















Both of the out-of-line AbcSection elements in Example 9–28 share the same default
table, ABCSECTIONTAB.
However, the Example 9–29 illustrates invalid default table sharing: recursive elements
(XyZSection) do not share the same out-of-line table.
Example 9–29

Invalid Default Table Sharing























9-26 Oracle XML DB Developer's Guide

Support for Recursive Schemas
















The following query cannot be rewritten.
SELECT XMLQuery('//XyzSection' PASSING OBJECT_VALUE RETURNING CONTENT)
FROM xyzcode;

Query Rewrite when DOCID is Present
Before processing // XPath expressions, check to find multiple occurrences of the
same element. If all occurrences under the // share the same defaultTable, then the
query can be rewritten to go against that table, using the DOCID. If there are other
occurrences of the same element under the root sharing that table, but not under //,
then the query cannot be rewritten. For example, consider this element structure:
 contains a  and a .  contains a .
Assume that both of the  elements are stored out of line and they share the
same default table. The query /Book//Chapter can be rewritten to go against the
default table for the  elements because all of the  elements
under  share the same default table. Thus, this XPath query is a
document-correlated recursive XPath query.
However, a query such as /Book/Part//Chapter cannot be rewritten, even though
all the  elements under  share the same table, because there is
another  element under , which is the document root that also
shares that table.
Consider the case where you are extracting //AbcSection with DOCID present, as in
the XML schema described in Example 9–28:
SELECT XMLQuery('//AbcSection' PASSING OBJECT_VALUE RETURNING CONTENT)
FROM abccodetab;

Both of the AbcSection elements are stored in the same table, abcsectiontab. The
extraction applies to the underlying table, abcsectiontab.
Consider this query when DOCID is present:
SELECT XMLQuery('/AbcCode/AbcSection//AbcSection'
PASSING OBJECT_VALUE RETURNING CONTENT)
FROM abccodetab;

In both this case and the previous case, all reachable AbcSection elements are stored
in the same out-of-line table. However, the first AbcSection element at
/AbcCode/AbcSection cannot be retrieved by this query. Since the join condition is

XML Schema Storage and Query: Advanced

9-27

Loading and Retrieving Large Documents with Collections

a DOCID, which cannot distinguish between different positions in the parent
document, the correct result cannot be achieved by a direct query on table
abcsectiontab. In this case, query rewrite does not occur since it is not a
document-correlated recursive XPath. If this top-level AbcSection were not stored
out of line with the rest, then the query could be rewritten.

Disabling DOCID Column Creation
You can disable the creation of column DOCID by specifying an OPTIONS parameter
when calling DBMS_XMLSCHEMA.registerSchema. This disables DOCID creation in
all XMLType tables generated during schema registration.
The OPTIONS parameter is an input parameter of data type PLS_INTEGER. Its default
value is 0, meaning no options are used. To inhibit generation of column DOCID, set
parameter OPTIONS to DBMS_XMLSCHEMA.REGISTER_NODOCID (which is 1).
See Also:

Oracle Database PL/SQL Packages and Types Reference

Loading and Retrieving Large Documents with Collections
Configuration file /xdbconfig.xml has parameters that control the amount of
memory used by the loading operation. These let you optimize the loading process,
provided the following conditions are met:
■

■

■

The document is loaded using one of the following:
–

Protocols (FTP, HTTP(S), or DAV)

–

PL/SQL function DBMS_XDB.createResource

–

A SQL INSERT statement into an XMLType table (but not an XMLType
column)

The document is XML schema-based and contains large collections (elements with
maxoccurs set to a large number).
Collections in the document are stored as OCTs. This is the default behavior.

In the following situations, these optimizations are sometimes suboptimal:
■

When there are triggers on the base table.

■

When the base table is partitioned.

■

When collections are stored out of line (applies only to SQL INSERT).

The basic idea behind this optimization is that it lets the collections be swapped into or
out of the memory in bounded sizes. As an illustration of this idea consider the
following example conforming to a purchase-order XML schema:


...

.
.

...



The purchase-order document here contains a collection of 10240 LineItem elements.
Creating the entire document in memory and then pushing it out to disk can lead to
9-28 Oracle XML DB Developer's Guide

Loading and Retrieving Large Documents with Collections

excessive memory usage and in some instances a load failure due to inadequate
system memory. To avoid that, you can create the documents in finite chunks of
memory called loadable units.
In the example case, assume that each line item needs 1 KB of memory and that you
want to use loadable units of 512 KB each. Each loadable unit then contains 512 line
items, and there are approximately 20 such units. If you want the entire memory
representation of the document to never exceed 2 MB, then you must ensure that at
any time no more than 4 loadable units are maintained in the memory. You can use an
LRU mechanism to swap out the loadable units.
By controlling the size of the loadable unit and the bound on the size of the document
you can tune the memory usage and performance of the load or retrieval. Typically a
larger loadable unit size translates into lesser number of disk accesses but takes up
more memory. This is controlled by the parameter xdbcore-loadableunit-size
whose default value is 16 KB. The user can indicate the amount of memory to be given
to the document by setting the xdbcore-xobmem-bound parameter which defaults
to 1 MB. The values to these parameters are specified in Kilobytes. So, the default
value of xdbcore-xobmem-bound is 1024 and that of
xdbcore-loadableunit-size is 16. These are soft limits that provide some
guidance to the system as to how to use the memory optimally.
When the document is loaded using FTP, the pattern in which the loadable units (LU)
are created and flushed to the disk is as follows:
No LUs
Create LU1[LineItems(LI):1-512]
LU1[LI:1-512], Create LU2[LI:513-1024]
.
.
LU1[LI:1-512],...,Create LU4[LI:1517:2028]













































. . .


















. . .

XML Schema Evolution

10-3

Using Copy-Based Schema Evolution














. . .
















































. . . -- A value for each US state abbreviation


10-4 Oracle XML DB Developer's Guide

Using Copy-Based Schema Evolution


















































copyEvolve Parameters and Errors
This is the signature of procedure DBMS_XMLSCHEMA.copyEvolve:
procedure copyEvolve(schemaURLs
newSchemas
transforms
preserveOldDocs
mapTabName
generateTables
force
schemaOwners
parallelDegree
options

IN
IN
IN
IN
IN
IN
IN
IN
IN
IN

XDB$STRING_LIST_T,
XMLSequenceType,
XMLSequenceType := NULL,
BOOLEAN := FALSE,
VARCHAR2 := NULL,
BOOLEAN := TRUE,
BOOLEAN := FALSE,
XDB$STRING_LIST_T := NULL
PLS_INTEGER := 0,
PLS_INTEGER := 0);

XML Schema Evolution

10-5

Using Copy-Based Schema Evolution

Table 10–1 describes the individual parameters. Table 10–2 describes the errors
associated with the procedure.
Table 10–1

Parameters of Procedure DBMS_XMLSCHEMA.COPYEVOLVE

Parameter

Description

schemaURLs

Varray of URLs of XML schemas to be evolved (varray of
VARCHAR2(4000). This should include the dependent
schemas as well. Unless the force parameter is TRUE, the URLs
should be in the dependency order, that is, if URL A comes
before URL B in the varray, then schema A should not be
dependent on schema B but schema B may be dependent on
schema A.

newSchemas

Varray of new XML schema documents (XMLType instances).
Specify this in exactly the same order as the corresponding
URLs. If no change is necessary in an XML schema, provide the
unchanged schema.

transforms

Varray of XSL documents (XMLType instances) that are applied
to XML schema based documents to make them conform to the
new schemas. Specify these in exactly the same order as the
corresponding URLs. If no transformations are required, this
parameter need not be specified.

preserveOldDocs

If this is TRUE, then the temporary tables holding old data are
not dropped at the end of schema evolution. See also
"Guidelines for Using Procedure COPYEVOLVE".

mapTabName

Specifies the name of table that maps old XMLType table or
column names to names of corresponding temporary tables.

generateTables

By default this parameter is TRUE. If FALSE then XMLType
tables or columns are not generated after registering new XML
schemas. If FALSE, preserveOldDocs must be TRUE and
mapTabName must not be NULL.

force

If this is TRUE, then errors during the registration of new
schemas are ignored. If there are circular dependencies among
the schemas, set this flag to TRUE to ensure that each schema is
stored even though there may be errors in registration.

schemaOwners

Varray of names of schema owners. Specify these in exactly the
same order as the corresponding URLs.

parallelDegree

Specifies the degree of parallelism to be used in a PARALLEL
hint during the data-copy stage. If this is 0 (default value), a
PARALLEL hint is absent from the data-copy statements.

options

Miscellaneous options. The only option is COPYEVOLVE_
BINARY_XML, which means to register the new XML schemas
for binary XML data and create the new tables or columns with
binary XML as the storage model.

Table 10–2

Errors Associated with Procedure DBMS_XMLSCHEMA.COPYEVOLVE

Error Number and
Message

Cause

Action

30942 XML Schema
Evolution error for
schema ''
table "."
column ''

The given XMLType table or
column that conforms to the
given XML schema had errors
during evolution. In the case of
a table, the column name is
empty. See also the more
specific error that follows this.

Based on the schema, table,
and column information in this
error and the more specific
error that follows, take
corrective action.

10-6 Oracle XML DB Developer's Guide

Using Copy-Based Schema Evolution

Table 10–2 (Cont.) Errors Associated with Procedure DBMS_
Error Number and
Message

Cause

Action

30943 XML Schema
'' is
dependent on XML
schema ''

Not all dependent XML
schemas were specified or the
schemas were not specified in
dependency order, that is, if
schema S1 is dependent on
schema S, S must appear before
S1.

Include the previously
unspecified schema in the list
of schemas or correct the order
in which the schemas are
specified. Then retry the
operation.

30944 Error during
rollback for XML schema
'' table
"." column
''

The given XMLType table or
column that conforms to the
given XML schema had errors
during a rollback of XML
schema evolution. For a table,
the column name is empty. See
also the more specific error that
follows this.

Based on the schema, table,
and column information in this
error and the more specific
error that follows, take
corrective action.

30945 Could not create
mapping table ''

A mapping table could not be
created during XML schema
evolution. See also the more
specific error that follows this.

Ensure that a table with the
given name does not exist and
retry the operation.

30946 XML Schema
Evolution warning:
temporary tables not
cleaned up

An error occurred after the
schema was evolved while
cleaning up temporary tables.
The schema evolution was
successful.

If you need to remove the
temporary tables, use the
mapping table to get the
temporary table names and
drop them.

Limitations of Procedure COPYEVOLVE
Keep in mind the following limitations when you use procedure DBMS_
XMLSCHEMA.copyEvolve:
■

■

■

Indexes, triggers, constraints, row-level security (RLS) policies, and other
metadata related to the XMLType tables that are dependent on the schemas are not
preserved. These must be re-created after evolution.
If top-level element names are changed, additional steps are required after
copyEvolve finishes executing. See "Top-Level Element Name Changes" on
page 10-8.
Copy-based evolution cannot be used if there is a table with an object-type column
that has an XMLType attribute that is dependent on any of the schemas to be
evolved. For example, consider this table:
CREATE TYPE t1 AS OBJECT (n NUMBER, x XMLType);
CREATE TABLE tab1 (e NUMBER, o t1) XMLType
COLUMN o.x XMLSchema "s1.xsd" ELEMENT "Employee";

This assumes that an XML schema with a top-level element Employee has been
registered under URL s1.xsd. It is not possible to evolve this XML schema,
because table tab1 with column o with XMLType attribute x is dependent on the
XML schema. Note that although copyEvolve does not handle XMLType object
attributes, it does raise an error in such cases.

XML Schema Evolution

10-7

Using Copy-Based Schema Evolution

Guidelines for Using Procedure COPYEVOLVE
The following general guideline applies to using procedure DBMS_
XMLSCHEMA.copyEvolve. The rest of this section describes specific guidelines that
can also be appropriate in particular contexts.
1.

Turn off the recycle bin, to prevent dropped tables from being copied to it:
ALTER SESSION SET RECYCLEBIN=off;

2.

Identify the XML schemas that are dependent on the XML schema that is to be
evolved. You can acquire the URLs of the dependent XML schemas using the
following query, where schema_to_be_evolved is the schema to be evolved,
and owner_of_schema_to_be_evolved is its owner (database user).
SELECT dxs.SCHEMA_URL, dxs.OWNER
FROM DBA_DEPENDENCIES dd, DBA_XML_SCHEMAS dxs
WHERE dd.REFERENCED_NAME = (SELECT INT_OBJNAME
FROM DBA_XML_SCHEMAS
WHERE SCHEMA_URL = schema_to_be_evolved
AND OWNER = owner_of_schema_to_be_evolved)
AND dxs.INT_OBJNAME = dd.NAME;

In many cases, no changes are needed in the dependent XML schemas. But if the
dependent XML schemas need to be changed, then you must also prepare new
versions of those XML schemas.
3.

If the existing instance documents do not conform to the new XML schema, then
you must provide an XSL style sheet that, when applied to an instance document,
transforms it to conform to the new schema. You must do this for each XML
schema identified in Step 2. The transformation must handle documents that
conform to all top-level elements in the new XML schema.

4.

Call procedure DBMS_XMLSCHEMA.copyEvolve, specifying the XML schema
URLs, new schemas, and transformation style sheet.

Top-Level Element Name Changes
Procedure DBMS_XMLSCHEMA.copyEvolve assumes that top-level elements have not
been dropped and that their names have not been changed in the new XML schemas.
If there are such changes in your new XML schemas, then you can call procedure
copyEvolve with parameter generateTables set to FALSE and parameter
preserveOldDocs set to TRUE. In this way, new tables are not generated, and the
temporary tables holding the old documents (backup copies) are not dropped at the
end of the procedure. You can then store the old documents in whatever form is
appropriate and drop the temporary tables. See "copyEvolve Parameters and Errors"
on page 10-5 for more details on using these parameters.

User-Created Virtual Columns of Tables Other Than Default Tables
For tables that are not default tables, any virtual columns that you create are not
re-created during copy-based evolution. If the columns are needed, then set parameter
preserveOldDocs to TRUE, create the tables, and copy the old documents after
procedure copyEvolve has finished.

Ensure that the XML Schema and Dependents Are Not Used by Concurrent
Sessions
Ensure that the XML schema and its dependents are not used by any concurrent
session during the XML schema evolution process. If other, concurrent sessions have

10-8 Oracle XML DB Developer's Guide

Using Copy-Based Schema Evolution

shared locks on this schema at the beginning of the evolution process, then procedure
DBMS_XMLSCHEMA.copyEvolve waits for these sessions to release the locks so that it
can acquire an exclusive lock. However, this lock is released immediately to allow the
rest of the process to continue.

Rollback When Procedure DBMS_XMLSCHEMA.COPYEVOLVE Raises an Error
Procedure DBMS_XMLSCHEMA.copyEvolve either completely succeeds or raises an
error, in which case it attempts to roll back as much of the operation as possible.
Evolving an XML schema involves many database DDL statements. When an error
occurs, compensating DDL statements are executed to undo the effect of all steps
executed to that point. If the old tables or schemas have been dropped, they are
re-created, but any table, column, and storage properties and any auxiliary structures
(such as indexes, triggers, constraints, and RLS policies) associated with the tables and
columns are lost.

Failed Rollback From Insufficient Privileges
In certain cases you cannot roll back the copy-based evolution operation. For example,
if table creation fails due to reasons not related to the new XML schema, then there is
no way to roll back. An example is failure due to insufficient privileges. The temporary
tables are not deleted even if preserveOldDocs is FALSE, so the data can be
recovered. If the mapTabName parameter is null, the mapping table name is
XDB$MAPTAB followed by a sequence number. The exact table name can be found
using a query such as the following:
SELECT TABLE_NAME FROM USER_TABLES WHERE TABLE_NAME LIKE 'XDB$MAPTAB%';

Privileges Needed for XML Schema Evolution
Copy-based XML schema evolution may involve dropping or creating data types.
Hence, you need type-related privileges such as DROP TYPE, CREATE TYPE, and
ALTER TYPE.
You need privileges to delete and register the XML schemas involved in the evolution.
You need all privileges on XMLType tables that conform to the schemas being evolved.
For XMLType columns, the ALTER TABLE privilege is needed on corresponding
tables. If there are schema-based XMLType tables or columns in other database
schemas, you need privileges such as the following:
■

CREATE ANY TABLE

■

CREATE ANY INDEX

■

SELECT ANY TABLE

■

UPDATE ANY TABLE

■

INSERT ANY TABLE

■

DELETE ANY TABLE

■

DROP ANY TABLE

■

ALTER ANY TABLE

■

DROP ANY INDEX

To avoid needing to grant all these privileges to the database- schema owner, Oracle
recommends that a database administrator perform the evolution if there are XML
schema-based XMLType table or columns belonging to other database schemas.

XML Schema Evolution

10-9

Using Copy-Based Schema Evolution

Updating Existing XML Instance Documents using a Style Sheet
After you modify a registered XML schema, you must update any existing XML
instance documents that use the XML schema. You do this by applying an XSLT style
sheet to each of the instance documents. The style sheet represents the difference
between the old and new XML schemas.
Example 10–2 is a style sheet, in file evolvePurchaseOrder.xsl, that transforms
existing purchase-order documents that use the old XML schema, so they use the new
XML schema instead.
Example 10–2

evolvePurchaseOrder.xsl: Style Sheet to Update Instance Documents







http://localhost:8080/source/schemas/poSource/xsd/purchaseOrder.xsd











































10-10 Oracle XML DB Developer's Guide

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XML Schema Evolution 10-11

Using Copy-Based Schema Evolution


























Examples of Using Procedure COPYEVOLVE
Example 10–3 loads a revised XML schema and evolution XSL style sheet into Oracle
XML DB Repository.
Example 10–3

Loading Revised XML Schema and XSL Style Sheet

DECLARE
res BOOLEAN;
BEGIN
res := DBMS_XDB.createResource(
-- Load revised XML schema
'/source/schemas/poSource/revisedPurchaseOrder.xsd',
bfilename('XMLDIR', 'revisedPurchaseOrder.xsd'),
nls_charset_id('AL32UTF8'));
res := DBMS_XDB.createResource(
-- Load revised XSL style sheet
'/source/schemas/poSource/evolvePurchaseOrder.xsl',
bfilename('XMLDIR', 'evolvePurchaseOrder.xsl'),
nls_charset_id('AL32UTF8'));
END;
/

Example 10–4 shows how to use procedure DBMS_XMLSCHEMA.copyEvolve to
evolve the XML schema purchaseOrder.xsd to revisedPurchaseOrder.xsd
using the XSL style sheet evolvePurchaseOrder.xsl.
Example 10–4

Updating an XML Schema using DBMS_XMLSCHEMA.COPYEVOLVE

BEGIN
DBMS_XMLSCHEMA.copyEvolve(
xdb$string_list_t('http://localhost:8080/source/schemas/poSource/xsd/purchaseOrder.xsd'),
XMLSequenceType(XDBURIType('/source/schemas/poSource/revisedPurchaseOrder.xsd').getXML()),
XMLSequenceType(XDBURIType('/source/schemas/poSource/evolvePurchaseOrder.xsl').getXML()));
END;
SELECT XMLQuery('$p/PurchaseOrder/LineItems/LineItem[1]'
PASSING po.OBJECT_VALUE AS "p" RETURNING CONTENT) line_item
FROM purchaseorder po

10-12 Oracle XML DB Developer's Guide

Using Copy-Based Schema Evolution

WHERE XMLExists('$p/PurchaseOrder[Reference="SBELL-2003030912333601PDT"]'
PASSING po.OBJECT_VALUE AS "p");
LINE_ITEM
-----------------------------------------------------------------------------
715515009058
2


The same query would have produced the following result before the schema
evolution:
LINE_ITEM
---------------------------------------------------------
A Night to Remember



Procedure DBMS_XMLSCHEMA.copyEvolve evolves registered XML schemas in such
a way that existing instance documents continue to remain valid.
Caution: Before executing procedure DBMS_
XMLSCHEMA.copyEvolve, always back up all registered XML
schemas and all XML documents that conform to them. Procedure
copyEvolve deletes all documents that conform to registered XML
schemas.

First, procedure copyEvolve copies the data in XML schema-based XMLType tables
and columns to temporary tables. It then drops the original tables and columns, and
deletes the old XML schemas. After registering the new XML schemas, it creates
XMLType tables and columns and populates them with data (unless parameter
GENTABLES is FALSE) but it does not create any auxiliary structures such as indexes,
constraints, triggers, and row-level security (RLS) policies. Procedure copyEvolve
creates the tables and columns as follows:
■

It creates default tables while registering the new schemas.

■

It creates tables that are not default tables using a statement of the following form:
CREATE TABLE table_name OF XMLType OID 'oid'
XMLSCHEMA schema_url ELEMENT element_name

where OID is the original OID of the table, before it was dropped.
■

It adds XMLType columns using a statement of the following form:
ALTER TABLE table_name ADD (column_name XMLType) XMLType COLUMN
column_name XMLSCHEMA schema_url ELEMENT element_name

When a new XML schema is registered, types are generated if the registration of the
corresponding old schema had generated types. If an XML schema was global before
the evolution, then it is also global after the evolution. Similarly, if an XML schema
was local before the evolution, then it is also local (owned by the same user) after the
evolution.
You have the option to preserve the temporary tables that contain the old documents,
by setting parameter preserveOldDocs to TRUE. All temporary tables are created in

XML Schema Evolution 10-13

Using Copy-Based Schema Evolution

the database schema of the current user. For XMLType tables, the temporary table has
the columns shown in Table 10–3.
Table 10–3

XML Schema Evolution: XMLType Table Temporary Table Columns

Name

Type

Comment

Data

CLOB

XML document from the old table, in CLOB
format.

OID

RAW(16)

OID of the corresponding row in the old table.

ACLOID

RAW(16)

This column is present only if the old table is
hierarchy enabled. ACLOID of corresponding
row in old table.

OWNERID

RAW(16)

This column is present only if old table is
hierarchy enabled. OWNERID of corresponding
row in old table.

For XMLType columns, the temporary table has the columns shown in Table 10–4.
Table 10–4

XML Schema Evolution: XMLType Column Temporary Table Columns

Name

Type

Comment

Data

CLOB

XML document from the old column, in CLOB
format.

RID

ROWID

ROWID of the corresponding row in the table
containing this column.

Procedure copyEvolve stores information about the mapping from the old table or
column name to the corresponding temporary table name in a separate table specified
by parameter mapTabName. If preserveOldDocs is TRUE, then the mapTabName
parameter must not be NULL, and it must not be the name of any existing table in the
current database schema. Each row in the mapping table has information about one of
the old tables/columns. Table 10–5 shows the mapping table columns.
Table 10–5

Procedure copyEvolve Mapping Table

Column Name

Column Type

Comment

SCHEMA_URL

VARCHAR2(700)

URL of the schema to which this table
or column conforms.

SCHEMA_OWNER

VARCHAR2(30)

Owner of the schema.

ELEMENT_NAME

VARCHAR2(256)

Element to which this table or column
conforms.

TABLE_NAME

VARCHAR2(65)

Qualified name of the table (.).

TABLE_OID

RAW(16)

OID of table.

COLUMN_NAME

VARCHAR2(4000)

Name of the column (NULL for
XMLType tables).

TEMP_TABNAME

VARCHAR2(30)

Name of temporary table that holds
the data for this table or column.

You can avoid generating any tables or columns after registering the new XML schema
by setting parameter GENTABLES to FALSE. If GENTABLES is FALSE, parameter
PRESERVEOLDDOCS must be TRUE and parameter MAPTABNAME must not be NULL.

10-14 Oracle XML DB Developer's Guide

Using In-Place XML Schema Evolution

This ensures that the data in the old tables is not lost. This is useful if you do not want
the tables to be created by the procedure, as described in section "copyEvolve
Parameters and Errors" on page 10-5.
By default, it is assumed that all XML schemas are owned by the current user. If this is
not true, then you must specify the owner of each XML schema in the schemaOwners
parameter.
See Also: Oracle Database SQL Language Reference for the complete
description of ALTER TABLE

Using In-Place XML Schema Evolution
In-place XML schema evolution makes changes to an XML schema without requiring
that existing data be copied, deleted, and reinserted. In-place evolution is thus much
faster than copy-based evolution. However, in-place evolution also has several
restrictions that do not apply to copy-based evolution.
You use procedure DBMS_XMLSCHEMA.inPlaceEvolve to perform in-place
evolution. Using this procedure, you identify the changes to be made to an existing
XML schema by specifying an XML schema-differences document, and you optionally
specify flags to be applied to the evolution process.
In-place evolution constructs a new version of an XML schema by applying changes
specified in a diffXML document, validates that new XML schema (against the XML
schema for XML schemas), constructs DDL statements to evolve the disk structures
used to store the XML instance documents associated with the XML schema, executes
these DDL statements, and replaces the old version of the XML schema with the new,
in that order. If the new version of the XML schema is not a valid schema, then
in-place evolution fails.

Restrictions for In-Place XML Schema Evolution
Because in-place XML schema evolution avoids copying data, it does not permit
arbitrary changes to an XML schema. This section describes why certain changes are
not permitted. For the list of changes supported by in-place evolution, see "Supported
Operations for In-Place XML Schema Evolution" on page 10-17.
The primary restriction on using in-place evolution can be stated generally as a
requirement that a given XML schema can be evolved in place in only a
backward-compatible way. Backward-compatible here means that any possible
instance document that would validate against a given XML schema must also
validate against a later (evolved) version of that XML schema.
This applies to all possible conforming instance documents, not only to existing instance
documents For XML data that is stored as binary XML, backward compatibility also
means that any XML schema annotations that affect binary XML treatment must not
change during evolution. Backward compatibility is described in section
"Backward-Compatibility Restrictions" on page 10-15.
In addition to this general backward-compatibility restriction, there are some other
restrictions for in-place evolution. These are described in section "Other Restrictions on
In-Place Evolution" on page 10-17.

Backward-Compatibility Restrictions
The restrictions described in this section ensure backward compatibility of an evolved
XML schema, so that any possible instance documents that satisfy the old XML
schema also satisfy the new schema.
XML Schema Evolution 10-15

Using In-Place XML Schema Evolution

Changes in Data Layout on Disk Certain changes to an XML schema alter the layout of the
associated instance documents on disk, and are therefore not permitted. This situation
is more common when the storage layer is tightly integrated with information derived
from the XML schema, as is the case for object-relational storage.
One such example is an XML schema, registered for object-relational storage mapping,
that is evolved by splitting a complex type into two complex types. In Example 10–5,
complex type ShippingInstructionsType is split into two complex types,
Person-Name and Contact-Info, and the ShippingInstructionsType
complex type is deleted.
Example 10–5

Splitting a Complex Type into Two Complex Types

These code excerpts show the definitions of the original
ShippingInstructionsType type and the new Person-Name and
Contact-Info types.



















Even if this XML schema has no associated instance documents, and therefore no data
copy is required, a change in the layout of existing tables is required to accommodate
future instance documents.
Reordering of XML Schema Constructs You cannot use in-place evolution to reorder
schema elements in a way that affects the DOM fidelity of instance documents. For
example, you cannot change the order of elements within a  element in a
complex type definition. As an example, if a complex type named
ShippingInstructionsType requires that its child elements name, address, and
telephone be in that order, you cannot use in-place evolution to change the order to
name, telephone, and address.
Changes from a Collection to a Non-Collection You cannot use in-place evolution to change
a collection to a non-collection. An example would be changing from a maxOccurs
value greater than one to a maxOccurs value of one. You cannot use in-place
evolution to delete an element from a complex type if the deletion requires that a
collection be evolved to a non-collection.
Model Changes within a complexType Element A model is one of the following elements:
group, choice, sequence, or all. Within a complexType element you cannot use

10-16 Oracle XML DB Developer's Guide

Using In-Place XML Schema Evolution

in-place evolution to either add a new model or replace an existing model with a
model of another type (for example, replace a choice element with a sequence
element). You can, however, add a global group element, that is, add a group element
outside of a complexType element.

Other Restrictions on In-Place Evolution
The restrictions on in-place XML schema evolution that are described in this section
are necessary for reasons other than backward compatibility of the evolved XML
schema.
Changes to Attributes in Namespace xdb Except for attribute xdb:defaultTable, you
cannot use in-place evolution to modify any attributes in namespace
http://xmlns.oracle.com/xdb (which has the predefined prefix xdb).
Changes from a Non-Collection to a Collection When XML data is stored object-relationally,
you cannot use in-place evolution to change a non-collection object type to a collection
object type. An example would be adding an element to a complex type with the
element name matching the name of an element already present in the type (or in
another type that is related to the first type through inheritance).

Supported Operations for In-Place XML Schema Evolution
This section describes operations that are supported for in-place schema evolution.
This list of supported operations is not necessarily exhaustive. Some of the operations
listed here are not permitted in specific contexts, which are specified. In particular,
some of the operations described here are not permitted for XML schemas that are
used with binary XML.
■

Add an optional element to a complex type or group: Always permitted. An
example is the addition of the optional element shipmethod in the following
complex type definition:









■

Add an optional attribute to a complex type or attribute group: Always
permitted. An example is the addition of the optional attribute shipbydate in the
following complex type definition:









■

Convert an element from simple type to complex type with simple content:
Supported only if the storage model is binary XML.

XML Schema Evolution 10-17

Using In-Place XML Schema Evolution

■

■

■

Modify the value attribute of an existing maxLength element: Always permitted.
The value can only be increased, not decreased.
Add an enumeration value: You can add a new enumeration value only to the end
of an enumeration list.
Add a global element: Always permitted. An example is the addition of the global
element PurchaseOrderComment in the following schema definition:

...

..


■
■

Add a global attribute: Always permitted.
Add or delete a global complex type: Always permitted. An example is the
addition of the global complex type ComplexAddressType in the following
schema definition:

....








...


■
■

■

■

Add or delete a global simple type: Always permitted.
Change the minOccurs attribute value: The value of minOccurs can only be
decreased.
Change the maxOccurs attribute value: The value of maxOccurs can only be
increased, and this is only possible for data stored as binary XML. That is, you
cannot make any change to the maxOccurs attribute for data stored
object-relationally.
Add or delete a global group or attributeGroup: Always permitted. An example
is the addition of an Instructions group in the following type definition:

...






...


■

■

Change the xdb:defaultTable attribute value: Always permitted. Changes are not
permitted to any other attributes in the xdb namespace.
Add, modify, or delete a comment or processing instruction: Always permitted.

10-18 Oracle XML DB Developer's Guide

Using In-Place XML Schema Evolution

Guidelines for Using In-Place XML Schema Evolution
The following guidelines apply to in-place XML-schema evolution:
■

Before you perform an in-place XML-schema evolution:
■

Back up all existing data (instance documents) for the XML schema to be
evolved.
Caution: Make sure that you back up your data before performing
in-place XML schema evolution, in case the result is not what you
intended. There is no rollback possible after an in-place evolution. If
any errors occur during evolution, or if you make a major mistake and
need to redo the entire operation, you must be able to go back to the
backup copy of your original data.

■

Perform a dry run using trace only, that is, without actually evolving the XML
schema or updating any instance documents, produce a trace of the update
operations that would be performed during evolution. To do this, set the flag
parameter value to only INPLACE_TRACE. Do not also use INPLACE_
EVOLVE.
After performing the dry run, examine the trace file, verifying that the listed
DDL operations are in fact those that you intend.

■

After you perform an in-place XML-schema evolution:
If you are accessing the database using a client that caches data, or if you are not
sure whether this is the case, then restart your client. Otherwise, the pre-evolution
version of the XML schema might continue to be used locally, with unpredictable
results.
See Also: Oracle Database Administrator's Guide for information
about using trace files

inPlaceEvolve Parameters
This is the signature of procedure DBMS_XMLSCHEMA.inPlaceEvolve:
procedure inPlaceEvolve(schemaURL IN VARCHAR2,
diffXML
IN XMLType,
flags
IN NUMBER);

Table 10–6 describes the individual parameters.
Table 10–6

Parameters of Procedure DBMS_XMLSCHEMA.INPLACEEVOLVE

Parameter

Description

schemaURL

URL of the XML schema to be evolved (VARCHAR2).

diffXML

XML document (XMLType instance) that conforms to the xdiff XML schema,
and that specifies the changes to apply and the locations in the XML schema
where the changes are to be applied. For information about how to create the
document for this parameter, see "Creating the Document for the diffXML
Parameter" on page 10-20.

XML Schema Evolution 10-19

Using In-Place XML Schema Evolution

Table 10–6 (Cont.) Parameters of Procedure DBMS_XMLSCHEMA.INPLACEEVOLVE
Parameter

Description

flags

A bit mask that controls the behavior of the procedure. You can set the
following bit values in this mask independently, summing them to define the
overall effect. The default flags value is 1 (bit 1 on, bit 2 off), meaning that
in-place evolution is performed and no trace is written.
■

■

INPLACE_EVOLVE (value 1, meaning that bit 1 is on) – Perform in-place
XML schema evolution. Construct a new XML schema and validate it
(against the XML schema for XML schemas). Construct the DDL
statements needed to evolve the instance-document disk structures.
Execute the DDL statements. Replace the old XML schema with the new.
INPLACE_TRACE (value 2, meaning that bit 2 is on) – Perform all steps
necessary for in-place evolution, except executing the DDL statements and
overwriting the old XML schema with the new, then write both the DDL
statements and the new XML schema to a trace file.

That is, each of the bits constructs the new XML schema, validates it, and
determines the steps needed to evolve the disk structures underlying the
instance documents. In addition:
■

■

Bit INPLACE_EVOLVE carries out those evolution steps and replaces the
old XML schema with the new.
Bit INPLACE_TRACE saves the evolution steps and the new XML schema
in a trace file (it does not carry out the evolution steps).

Procedure DBMS_XMLSCHEMA.inPlaceEvolve raises an error in the following cases:
■

An XPath expression is invalid, or is syntactically correct but does not target a
node in the XML schema.

■

The diffXML document does not conform to the xdiff XML schema.

■

The change makes the XML schema invalid or not well formed.

■

■

A generated DDL statement (CREATE TYPE, ALTER TYPE, and so on) causes a
problem when it is executed.
An index object associated with an XMLType table is in an unsafe state, which
could be caused by partition management operations.

Creating the Document for the diffXML Parameter
The value of the diffXML parameter to procedure DBMS_
XMLSCHEMA.inPlaceEvolve is an XML document (as an XMLType instance) that
specifies the changes to be applied to an XML schema for in-place evolution. This
diffXML document contains a sequence of operations that describe the changes
between the old XML schema and the new (the intended evolution result). The
changes specified by the diffXML document are applied in order.
You must create the XML document to be used for the diffXML parameter You can do
this in any of the following ways:
■

The XMLDiff JavaBean (oracle.xml.differ.XMLDiff)

■

The xmldiff command-line utility

■

SQL function XMLDiff

The diffXML parameter document must conform to the xdiff XML schema.
The rest of this section presents examples of some operations in a document that
conforms to the xdiff XML schema.

10-20 Oracle XML DB Developer's Guide

Using In-Place XML Schema Evolution

See Also:
■

■

■

■

"xdiff.xsd: XML Schema for Comparing Schemas for In-Place
Evolution" on page A-28
Oracle XML Developer's Kit Programmer's Guide for information
on using the XMLDiff JavaBean
Oracle XML Developer's Kit Programmer's Guide for information
on command-line utility xmldiff
Oracle Database SQL Language Reference for information on SQL
function XMLDiff

diffXML Operations and Examples
This section describes some operations that can be specified in the document for the
diffXML document supplied to procedure DBMS_XMLSCHEMA.inPlaceEvolve. It
presents an example XML document that conforms to the xdiff XML schema.
The  element is used for most of the supported changes, such as
adding a new attribute to a complex type or appending a new element to a group.
The  element specifies that a node of the given type should
be inserted before the specified node. The xpath attribute specifies the location of the
specified node and the node-type attribute specifies the type of node to be inserted.
The node to be inserted is specified by the  child element. The
 element is mainly used for inserting comments and
processing instructions, and for changing and adding add annotation elements.
The  element specifies that the node with the given XPath (specified
by the xpath attribute) should be deleted along with all its children. For example, you
can use this element to delete comments and annotation elements. You can also use
this element, in conjunction with  or , to
make changes to an existing node.
Example 10–6 shows an XML document for the diffXML parameter that specifies the
following changes:

Example 10–6

■

Delete complex type PartType.

■

Add complex type PartType with a maximum length of 28.

■

Add a comment before element ShippingInstructions.

■

Add a required element shipmethod to element ShippingInstructions.

diffXML Parameter Document



















10-22 Oracle XML DB Developer's Guide

11
Transforming and Validating XMLType Data
This chapter describes the SQL functions and XMLType APIs for transforming
XMLType data using XSLT style sheets. It also explains the various functions and APIs
available for validating the XMLType instance against an XML schema.
This chapter contains these topics:
■

Transforming XMLType Instances

■

XMLTRANSFORM and XMLType.transform(): Examples

■

Validating XMLType Instances

■

Validating XML Data Stored as XMLType: Examples

Transforming XMLType Instances
XML documents have structure but no format. To add format to the XML documents
you can use Extensible Stylesheet Language (XSL). XSL provides a way of displaying
XML semantics. It can map XML elements into other formatting or mark-up languages
such as HTML.
In Oracle XML DB, XMLType instances or XML data stored in XMLType tables,
columns, or views in Oracle Database, can be (formatted) transformed into HTML,
XML, and other mark-up languages, using XSL style sheets and XMLType method
transform(). This process conforms to the W3C XSL Transformations 1.0
Recommendation.
XMLType instance can be transformed in the following ways:
■

■

Using Oracle SQL function XMLtransform or XMLType method transform()
in the database.
Using Oracle XML Developer's Kit transformation options in the middle tier, such
as XSLT Processor for Java.
See Also:
■

■

Chapter 3, "Using Oracle XML DB", the section, "XSL
Transformation and Oracle XML DB" on page 3-64
"PL/SQL XSLT Processor for XMLType (DBMS_
XSLPROCESSOR)" on page 13-20

Transforming and Validating XMLType Data

11-1

XMLTRANSFORM and XMLType.transform(): Examples

SQL Function XMLTRANSFORM and XMLType Method TRANSFORM()
Figure 11–1 shows the syntax of Oracle SQL function XMLtransform. This function
takes as arguments an XMLType instance and an XSLT style sheet. The style sheet can
be an XMLType instance or a VARCHAR2 string literal. It applies the style sheet to the
instance and returns an XMLType instance.
Figure 11–1 XMLTRANSFORM Syntax
XMLType_instance
XMLTRANSFORM

(

XMLType_instance

,

)
string

You can alternatively use XMLType method transform() as an alternative to Oracle
SQL function XMLtransform. It has the same functionality.
Figure 11–2 shows how XMLtransform transforms an XML document by using an
XSLT style sheet. It returns the processed output as XML, HTML, and so on, as
specified by the XSLT style sheet. You typically use XMLtransform when retrieving
or generating XML documents stored as XMLType in the database.
See Also: Figure 1–1, "XMLType Storage and Oracle XML DB
Repository" in Chapter 1, "Introduction to Oracle XML DB"
Figure 11–2 Using XMLTRANSFORM
XSL style sheet
XMLType instance
(table, column, view)

XMLtransform

transformed XMLType instance
(HTML, XML, ...)

XMLTRANSFORM and XMLType.transform(): Examples
The examples in this section illustrate how to use Oracle SQL function
XMLtransform and XMLType method transform() to transform XML data stored
as XMLType to various formats.
Example 11–1 sets up an XML schema and tables that are needed to run other
examples in this chapter. The call to deleteSchema here ensures that there is no
existing XML schema before creating one. If no such schema exists, then
deleteSchema produces an error.
Example 11–1

Registering an XML Schema and Inserting XML Data

BEGIN
-- Delete the schema, if it already exists.
DBMS_XMLSCHEMA.deleteSchema('http://www.example.com/schemas/ipo.xsd',4);
END;
/
BEGIN
-- Register the schema
DBMS_XMLSCHEMA.registerSchema(
SCHEMAURL => 'http://www.example.com/schemas/ipo.xsd',
SCHEMADOC => '

















































',
=> TRUE,
=> TRUE);

END;
/
-- Create table to hold XML instance documents
DROP TABLE po_tab;

Transforming and Validating XMLType Data

11-3

XMLTRANSFORM and XMLType.transform(): Examples

CREATE TABLE po_tab (id NUMBER, xmlcol XMLType)
XMLType COLUMN xmlcol
XMLSCHEMA "http://www.example.com/schemas/ipo.xsd"
ELEMENT "purchaseOrder";
INSERT INTO po_tab
VALUES(1, XMLType(
'


Helen Zoe
121 Broadway
Cardiff
Wales
UK
CF2 1QJ


Robert Smith
8 Oak Avenue
Old Town
CA
US
95819



Lapis necklace
1
99.95
Want this for the holidays!
1999-12-05


'));

Example 11–2 shows how to retrieve a style sheet using SQL function XMLtransform
and DBURIType. See Chapter 20, "Accessing Data Through URIs" for information
about DBURIType.
Example 11–2

Retrieving a Style Sheet using XMLTRANSFORM and DBURITYPE

DROP TABLE stylesheet_tab;
CREATE TABLE stylesheet_tab (id NUMBER, stylesheet XMLType);
INSERT INTO stylesheet_tab
VALUES (1,
XMLType(
'





11-4 Oracle XML DB Developer's Guide

XMLTRANSFORM and XMLType.transform(): Examples





:






ipo:purchaseOrder:
shipTo:
name:Helen Zoe
street:100 Broadway
city:Cardiff
state:Wales
country:UK
zip:CF2 1QJ

billTo:
name:Robert Smith
street:8 Oak Avenue
city:Old Town
state:CA
country:US
zip:95819

items:







:











Internal








Actions








Oracle-Supplied XML Schemas and Examples A-39

XSL Style Sheet Example, PurchaseOrder.xsl





User


Date

























Requestor











User











Cost Center















Ship To















A-40 Oracle XML DB Developer's Guide

XSL Style Sheet Example, PurchaseOrder.xsl

Name










Address












Telephone



















Items:













Oracle-Supplied XML Schemas and Examples A-41

XSL Style Sheet Example, PurchaseOrder.xsl


ItemNumber




Description




PartId




Quantity




Unit Price




Total Price


































A-42 Oracle XML DB Developer's Guide

Loading XML Data using C (OCI)



































Loading XML Data using C (OCI)
Example A–4 is a C program that inserts XML data into an XMLType table. It is partly
listed in Chapter 3, "Using Oracle XML DB", "Loading XML Content using C" on
page 3-7.
Example A–4 Inserting XML Data into an XMLType Table using C
#include "stdio.h"
#include 
#include 
#include 
#include 
OCIEnv *envhp;
OCIError *errhp;
OCISvcCtx *svchp;
OCIStmt *stmthp;
OCIServer *srvhp;
OCIDuration dur;
OCISession *sesshp;
oratext *username = "QUINE";
oratext *password = "************";
/* Replace with real password */
oratext *filename = "AMCEWEN-20021009123336171PDT.xml";
oratext *schemaloc = "http://localhost:8080/source/schemas/poSource/xsd/purchaseOrder.xsd";

Oracle-Supplied XML Schemas and Examples A-43

Loading XML Data using C (OCI)

/* Execute a SQL statement that binds XML data */
sword exec_bind_xml(OCISvcCtx *svchp, OCIError *errhp, OCIStmt *stmthp,
void *xml,
OCIType *xmltdo, OraText *sqlstmt)
{
OCIBind *bndhp1 = (OCIBind *) 0;
sword status = 0;
OCIInd ind = OCI_IND_NOTNULL;
OCIInd *indp = &ind;
if(status = OCIStmtPrepare(stmthp, errhp, (OraText *)sqlstmt,
(ub4)strlen((const char *)sqlstmt),
(ub4) OCI_NTV_SYNTAX, (ub4) OCI_DEFAULT))
return OCI_ERROR;
if(status = OCIBindByPos(stmthp, &bndhp1, errhp, (ub4) 1, (dvoid *) 0,
(sb4) 0, SQLT_NTY, (dvoid *) 0, (ub2 *)0,
(ub2 *)0, (ub4) 0, (ub4 *) 0, (ub4) OCI_DEFAULT))
return OCI_ERROR;
if(status = OCIBindObject(bndhp1, errhp, (CONST OCIType *) xmltdo,
(dvoid **) &xml, (ub4 *) 0,
(dvoid **) &indp, (ub4 *) 0))
return OCI_ERROR;
if(status = OCIStmtExecute(svchp, stmthp, errhp, (ub4) 1, (ub4) 0,
(CONST OCISnapshot*) 0, (OCISnapshot*) 0,
(ub4) OCI_DEFAULT))
return OCI_ERROR;
return OCI_SUCCESS;
}
/* Initialize OCI handles, and connect */
sword init_oci_connect()
{
sword status;
if (OCIEnvCreate((OCIEnv **) &(envhp), (ub4) OCI_OBJECT,
(dvoid *) 0, (dvoid * (*)(dvoid *,size_t)) 0,
(dvoid * (*)(dvoid *, dvoid *, size_t)) 0,
(void (*)(dvoid *, dvoid *)) 0, (size_t) 0, (dvoid **) 0))
{
printf("FAILED: OCIEnvCreate()\n");
return OCI_ERROR;
}
/* Allocate error handle */
if (OCIHandleAlloc((dvoid *) envhp, (dvoid **) &(errhp),
(ub4) OCI_HTYPE_ERROR, (size_t) 0, (dvoid **) 0))
{
printf("FAILED: OCIHandleAlloc() on errhp\n");
return OCI_ERROR;
}
/* Allocate server handle */
if (status = OCIHandleAlloc((dvoid *) envhp, (dvoid **) &srvhp,
(ub4) OCI_HTYPE_SERVER, (size_t) 0, (dvoid **) 0))
{
printf("FAILED: OCIHandleAlloc() on srvhp\n");
return OCI_ERROR;
}
/* Allocate service context handle */
if (status = OCIHandleAlloc((dvoid *) envhp,
(dvoid **) &(svchp), (ub4) OCI_HTYPE_SVCCTX,
(size_t) 0, (dvoid **) 0))
{
printf("FAILED: OCIHandleAlloc() on svchp\n");
return OCI_ERROR;
}
/* Allocate session handle */
if (status = OCIHandleAlloc((dvoid *) envhp, (dvoid **) &sesshp ,
(ub4) OCI_HTYPE_SESSION, (size_t) 0, (dvoid **) 0))
{

A-44 Oracle XML DB Developer's Guide

Loading XML Data using C (OCI)

printf("FAILED: OCIHandleAlloc() on sesshp\n");
return OCI_ERROR;
}
/* Allocate statement handle */
if (OCIHandleAlloc((dvoid *)envhp, (dvoid **) &stmthp,
(ub4)OCI_HTYPE_STMT, (CONST size_t) 0, (dvoid **) 0))
{
printf("FAILED: OCIHandleAlloc() on stmthp\n");
return status;
}
if (status = OCIServerAttach((OCIServer *) srvhp, (OCIError *) errhp,
(CONST oratext *)"", 0, (ub4) OCI_DEFAULT))
{
printf("FAILED: OCIServerAttach() on srvhp\n");
return OCI_ERROR;
}
/* Set server attribute to service context */
if (status = OCIAttrSet((dvoid *) svchp, (ub4) OCI_HTYPE_SVCCTX,
(dvoid *) srvhp, (ub4) 0, (ub4) OCI_ATTR_SERVER,
(OCIError *) errhp))
{
printf("FAILED: OCIAttrSet() on svchp\n");
return OCI_ERROR;
}
/* Set user attribute to session */
if (status = OCIAttrSet((dvoid *)sesshp, (ub4) OCI_HTYPE_SESSION,
(dvoid *)username,
(ub4) strlen((const char *)username),
(ub4) OCI_ATTR_USERNAME, (OCIError *) errhp))
{
printf("FAILED: OCIAttrSet() on authp for user\n");
return OCI_ERROR;
}
/* Set password attribute to session */
if (status = OCIAttrSet((dvoid *) sesshp, (ub4) OCI_HTYPE_SESSION,
(dvoid *)password,
(ub4) strlen((const char *)password),
(ub4) OCI_ATTR_PASSWORD, (OCIError *) errhp))
{
printf("FAILED: OCIAttrSet() on authp for password\n");
return OCI_ERROR;
}
/* Begin a session */
if (status = OCISessionBegin((OCISvcCtx *) svchp,
(OCIError *) errhp,
(OCISession *) sesshp, (ub4) OCI_CRED_RDBMS,
(ub4) OCI_STMT_CACHE))
{
printf("FAILED: OCISessionBegin(). Make sure database is up and the username/password is valid. \n");
return OCI_ERROR;
}
/* Set session attribute to service context */
if (status = OCIAttrSet((dvoid *) svchp, (ub4) OCI_HTYPE_SVCCTX,
(dvoid *)sesshp, (ub4) 0, (ub4) OCI_ATTR_SESSION,
(OCIError *) errhp))
{
printf("FAILED: OCIAttrSet() on svchp\n");
return OCI_ERROR;
}
}
/* Free OCI handles, and disconnect
void free_oci()
{
sword status = 0;

*/

Oracle-Supplied XML Schemas and Examples A-45

Loading XML Data using C (OCI)

/* End the session */
if (status = OCISessionEnd((OCISvcCtx *)svchp, (OCIError *)errhp,
(OCISession *)sesshp, (ub4) OCI_DEFAULT))
{
if (envhp)
OCIHandleFree((dvoid *)envhp, OCI_HTYPE_ENV);
return;
}
/* Detach from the server */
if (status = OCIServerDetach((OCIServer *)srvhp, (OCIError *)errhp,
(ub4)OCI_DEFAULT))
{
if (envhp)
OCIHandleFree((dvoid *)envhp, OCI_HTYPE_ENV);
return;
}
/* Free the handles */
if (stmthp) OCIHandleFree((dvoid *)stmthp, (ub4) OCI_HTYPE_STMT);
if (sesshp) OCIHandleFree((dvoid *)sesshp, (ub4) OCI_HTYPE_SESSION);
if (svchp) OCIHandleFree((dvoid *)svchp, (ub4) OCI_HTYPE_SVCCTX);
if (srvhp) OCIHandleFree((dvoid *)srvhp, (ub4) OCI_HTYPE_SERVER);
if (errhp) OCIHandleFree((dvoid *)errhp, (ub4) OCI_HTYPE_ERROR);
if (envhp) OCIHandleFree((dvoid *)envhp, (ub4) OCI_HTYPE_ENV);
return;
}
void main()
{
OCIType *xmltdo;
xmldocnode *doc;
ocixmldbparam params[1];
xmlerr
err;
xmlctx *xctx;
oratext *ins_stmt;
sword
status;
xmlnode *root;
oratext buf[10000];
/* Initialize envhp, svchp, errhp, dur, stmthp */
init_oci_connect();
/* Get an XML context */
params[0].name_ocixmldbparam = XCTXINIT_OCIDUR;
params[0].value_ocixmldbparam = &dur;
xctx = OCIXmlDbInitXmlCtx(envhp, svchp, errhp, params, 1);
if (!(doc = XmlLoadDom(xctx, &err, "file", filename,
"schema_location", schemaloc, NULL)))
{
printf("Parse failed.\n");
return;
}
else
printf("Parse succeeded.\n");
root = XmlDomGetDocElem(xctx, doc);
printf("The xml document is :\n");
XmlSaveDom(xctx, &err, (xmlnode *)doc, "buffer", buf, "buffer_length", 10000, NULL);
printf("%s\n", buf);
/* Insert the document into my_table */
ins_stmt = (oratext *)"insert into purchaseorder values (:1)";
status = OCITypeByName(envhp, errhp, svchp, (const text *) "SYS",
(ub4) strlen((const char *)"SYS"), (const text *) "XMLTYPE",
(ub4) strlen((const char *)"XMLTYPE"), (CONST text *) 0,
(ub4) 0, OCI_DURATION_SESSION, OCI_TYPEGET_HEADER,
(OCIType **) &xmltdo);
if (status == OCI_SUCCESS)

A-46 Oracle XML DB Developer's Guide

Initializing and Terminating an XML Context (OCI)

{
status = exec_bind_xml(svchp, errhp, stmthp, (void *)doc,
xmltdo, ins_stmt);
}
if (status == OCI_SUCCESS)
printf ("Insert successful\n");
else
printf ("Insert failed\n");
/* Free XML instances */
if (doc) XmlFreeDocument((xmlctx *)xctx, (xmldocnode *)doc);
/* Free XML CTX */
OCIXmlDbFreeXmlCtx(xctx);
free_oci();
}

Initializing and Terminating an XML Context (OCI)
Example A–5 shows how to use OCI functions OCIXmlDbInitXmlCtx() and
OCIXmlDbFreeXmlCtx() to initialize and terminate the XML context. It constructs
an XML document using the C DOM API and saves it to the database.
Example A–5 is partially listed in Chapter 16, "Using the C API for XML", "Initializing
and Terminating an XML Context" on page 16-3. It assumes that the following SQL
code has first been executed to create table my_table in database schema CAPIUSER:
CONNECT CAPIUSER
Enter password: 
Connected.
CREATE TABLE my_table OF XMLType;
Example A–5 Using OCIXmlDbInitXmlCtx() and OCIXmlDbFreeXmlCtx()
#ifndef S_ORACLE
#include 
#endif
#ifndef ORATYPES_ORACLE
#include 
#endif
#ifndef XML_ORACLE
#include 
#endif
#ifndef OCIXML_ORACLE
#include 
#endif
#ifndef OCI_ORACLE
#include 
#endif
#include 
typedef struct test_ctx {
OCIEnv *envhp;
OCIError *errhp;
OCISvcCtx *svchp;
OCIStmt *stmthp;
OCIServer *srvhp;
OCIDuration dur;
OCISession *sesshp;
oratext *username;
Oracle-Supplied XML Schemas and Examples A-47

Initializing and Terminating an XML Context (OCI)

oratext *password;
} test_ctx;
/* Helper function 1: execute a sql statement which binds xml data */
STATICF sword exec_bind_xml(OCISvcCtx *svchp,
OCIError *errhp,
OCIStmt *stmthp,
void *xml,
OCIType *xmltdo,
OraText *sqlstmt);
/* Helper function 2: Initialize OCI handles and connect */
STATICF sword init_oci_handles(test_ctx *ctx);
/* Helper function 3: Free OCI handles and disconnect */
STATICF sword free_oci_handles(test_ctx *ctx);
void main()
{
test_ctx temp_ctx;
test_ctx *ctx = &temp_ctx;
OCIType *xmltdo = (OCIType *) 0;
xmldocnode *doc = (xmldocnode *)0;
ocixmldbparam params[1];
xmlnode *quux, *foo, *foo_data, *top;
xmlerr err;
sword status = 0;
xmlctx *xctx;
oratext ins_stmt[] = "insert into my_table values (:1)";
oratext tlpxml_test_sch[] = "";
ctx->username = (oratext *)"CAPIUSER";
ctx->password = (oratext *)"************";
/* Replace with real password */
/* Initialize envhp, svchp, errhp, dur, stmthp */
init_oci_handles(ctx);
/* Get an xml context */
params[0].name_ocixmldbparam = XCTXINIT_OCIDUR;
params[0].value_ocixmldbparam = &ctx->dur;
xctx = OCIXmlDbInitXmlCtx(ctx->envhp, ctx->svchp, ctx->errhp, params, 1);
/* Start processing - first, check that this DOM supports XML 1.0 */
printf("\n\nSupports XML 1.0? : %s\n",
XmlHasFeature(xctx, (oratext *) "xml", (oratext *) "1.0") ?
"YES" : "NO");
/* Parse a document */
if (!(doc = XmlLoadDom(xctx, &err, "buffer", tlpxml_test_sch,
"buffer_length", sizeof(tlpxml_test_sch)-1,
"validate", TRUE, NULL)))
{
printf("Parse failed, code %d\n", err);
}
else
{
/* Get the document element */
top = (xmlnode *)XmlDomGetDocElem(xctx, doc);
/* Print out the top element */

A-48 Oracle XML DB Developer's Guide

Initializing and Terminating an XML Context (OCI)

printf("\n\nOriginal top element is :\n");
XmlSaveDom(xctx, &err, top, "stdio", stdout, NULL);
/* Print out the document-note that the changes are reflected here */
printf("\n\nOriginal document is :\n");
XmlSaveDom(xctx, &err, (xmlnode *)doc, "stdio", stdout, NULL);
/* Create some elements and add them to the document */
quux = (xmlnode *) XmlDomCreateElem(xctx ,doc, (oratext *) "QUUX");
foo = (xmlnode *) XmlDomCreateElem(xctx, doc, (oratext *) "FOO");
foo_data = (xmlnode *) XmlDomCreateText(xctx, doc, (oratext *) "data");
foo_data = XmlDomAppendChild(xctx, (xmlnode *) foo, (xmlnode *) foo_data);
foo = XmlDomAppendChild(xctx, quux, foo);
quux = XmlDomAppendChild(xctx, top, quux);
/* Print out the top element */
printf("\n\nNow the top element is :\n");
XmlSaveDom(xctx, &err, top, "stdio", stdout, NULL);
/* Print out the document. Note that the changes are reflected here */
printf("\n\nNow the document is :\n");
XmlSaveDom(xctx, &err, (xmlnode *)doc, "stdio", stdout, NULL);
/* Insert the document into my_table */
status = OCITypeByName(ctx->envhp, ctx->errhp, ctx->svchp,
(const text *) "SYS", (ub4) strlen((char *)"SYS"),
(const text *) "XMLTYPE",
(ub4) strlen((char *)"XMLTYPE"), (CONST text *) 0,
(ub4) 0, OCI_DURATION_SESSION, OCI_TYPEGET_HEADER,
(OCIType **) &xmltdo);
if (status == OCI_SUCCESS)
{
exec_bind_xml(ctx->svchp, ctx->errhp, ctx->stmthp, (void *)doc, xmltdo,
ins_stmt);
}
}
/* Free xml ctx */
OCIXmlDbFreeXmlCtx(xctx);
/* Free envhp, svchp, errhp, stmthp */
free_oci_handles(ctx);
}
/* Helper function 1: execute a SQL statement that binds xml data */
STATICF sword exec_bind_xml(OCISvcCtx *svchp,
OCIError *errhp,
OCIStmt *stmthp,
void *xml,
OCIType *xmltdo,
OraText *sqlstmt)
{
OCIBind *bndhp1 = (OCIBind *) 0;
sword status = 0;
OCIInd ind = OCI_IND_NOTNULL;
OCIInd *indp = &ind;
if(status = OCIStmtPrepare(stmthp, errhp, (OraText *)sqlstmt,
(ub4)strlen((char *)sqlstmt),
(ub4) OCI_NTV_SYNTAX, (ub4) OCI_DEFAULT)) {
printf("Failed OCIStmtPrepare\n");
return OCI_ERROR;

Oracle-Supplied XML Schemas and Examples A-49

Initializing and Terminating an XML Context (OCI)

}
if(status = OCIBindByPos(stmthp, &bndhp1, errhp, (ub4) 1, (dvoid *) 0,
(sb4) 0, SQLT_NTY, (dvoid *) 0, (ub2 *)0,
(ub2 *)0, (ub4) 0, (ub4 *) 0, (ub4) OCI_DEFAULT)) {
printf("Failed OCIBindByPos\n");
return OCI_ERROR;
}
if(status = OCIBindObject(bndhp1, errhp, (CONST OCIType *) xmltdo, (dvoid **)
&xml,
(ub4 *) 0, (dvoid **) &indp, (ub4 *) 0)) {
printf("Failed OCIBindObject\n");
return OCI_ERROR;
}
if(status = OCIStmtExecute(svchp, stmthp, errhp, (ub4) 1, (ub4) 0,
(CONST OCISnapshot*) 0, (OCISnapshot*) 0,
(ub4) OCI_DEFAULT)) {
printf("Failed OCIStmtExecute\n");
return OCI_ERROR;
}
return OCI_SUCCESS;
}
/* Helper function 2: Initialize OCI handles and connect */
STATICF sword init_oci_handles(test_ctx *ctx)
{
sword status;
ctx->dur = OCI_DURATION_SESSION;
if (OCIEnvCreate((OCIEnv **) &(ctx->envhp), (ub4) OCI_OBJECT,
(dvoid *) 0, (dvoid * (*)(dvoid *,size_t)) 0,
(dvoid * (*)(dvoid *, dvoid *, size_t)) 0,
(void (*)(dvoid *, dvoid *)) 0, (size_t) 0, (dvoid **) 0))
{
printf("FAILED: OCIEnvCreate()\n");
return OCI_ERROR;
}
/* Allocate error handle */
if (OCIHandleAlloc((dvoid *) ctx->envhp, (dvoid **) &(ctx->errhp),
(ub4) OCI_HTYPE_ERROR, (size_t) 0, (dvoid **) 0))
{
printf("FAILED: OCIHandleAlloc() on errhp\n");
return OCI_ERROR;
}
/* Allocate server handle */
if (status = OCIHandleAlloc((dvoid *) ctx->envhp, (dvoid **) &ctx->srvhp,
(ub4) OCI_HTYPE_SERVER, (size_t) 0, (dvoid **) 0))
{
printf("FAILED: OCIHandleAlloc() on srvhp\n");
return OCI_ERROR;
}
/* Allocate service context handle */
if (status = OCIHandleAlloc((dvoid *) ctx->envhp,
(dvoid **) &(ctx->svchp), (ub4) OCI_HTYPE_SVCCTX,
(size_t) 0, (dvoid **) 0))
{
printf("FAILED: OCIHandleAlloc() on svchp\n");
return OCI_ERROR;
}
/* Allocate session handle */
if (status = OCIHandleAlloc((dvoid *) ctx->envhp, (dvoid **) &ctx->sesshp ,
(ub4) OCI_HTYPE_SESSION, (size_t) 0, (dvoid **) 0))

A-50 Oracle XML DB Developer's Guide

Initializing and Terminating an XML Context (OCI)

{
printf("FAILED: OCIHandleAlloc() on sesshp\n");
return OCI_ERROR;
}
/* Allocate statement handle */
if (OCIHandleAlloc((dvoid *)ctx->envhp, (dvoid **) &ctx->stmthp,
(ub4)OCI_HTYPE_STMT, (CONST size_t) 0, (dvoid **) 0))
{
printf("FAILED: OCIHandleAlloc() on stmthp\n");
return status;
}
if (status = OCIServerAttach((OCIServer *) ctx->srvhp, (OCIError *) ctx->errhp,
(CONST oratext *)"", 0, (ub4) OCI_DEFAULT))
{
printf("FAILED: OCIServerAttach() on srvhp\n");
return OCI_ERROR;
}
/* Set server attribute to service context */
if (status = OCIAttrSet((dvoid *) ctx->svchp, (ub4) OCI_HTYPE_SVCCTX,
(dvoid *) ctx->srvhp, (ub4) 0, (ub4) OCI_ATTR_SERVER,
(OCIError *) ctx->errhp))
{
printf("FAILED: OCIAttrSet() on svchp\n");
return OCI_ERROR;
}
/* Set user attribute to session */
if (status = OCIAttrSet((dvoid *)ctx->sesshp, (ub4) OCI_HTYPE_SESSION,
(dvoid *)ctx->username,
(ub4) strlen((char *)ctx->username),
(ub4) OCI_ATTR_USERNAME, (OCIError *) ctx->errhp))
{
printf("FAILED: OCIAttrSet() on authp for user\n");
return OCI_ERROR;
}
/* Set password attribute to session */
if (status = OCIAttrSet((dvoid *) ctx->sesshp, (ub4) OCI_HTYPE_SESSION,
(dvoid *)ctx->password,
(ub4) strlen((char *)ctx->password),
(ub4) OCI_ATTR_PASSWORD, (OCIError *) ctx->errhp))
{
printf("FAILED: OCIAttrSet() on authp for password\n");
return OCI_ERROR;
}
/* Begin a session */
if (status = OCISessionBegin((OCISvcCtx *) ctx->svchp,
(OCIError *) ctx->errhp,
(OCISession *) ctx->sesshp, (ub4) OCI_CRED_RDBMS,
(ub4) OCI_STMT_CACHE))
{
printf("FAILED: OCISessionBegin(). Make sure database is up and the \
username/password is valid. \n");
return OCI_ERROR;
}
/* Set session attribute to service context */
if (status = OCIAttrSet((dvoid *) ctx->svchp, (ub4) OCI_HTYPE_SVCCTX,
(dvoid *)ctx->sesshp, (ub4) 0, (ub4) OCI_ATTR_SESSION,
(OCIError *) ctx->errhp))
{
printf("FAILED: OCIAttrSet() on svchp\n");
return OCI_ERROR;

Oracle-Supplied XML Schemas and Examples A-51

Initializing and Terminating an XML Context (OCI)

}
return status;
}
/* Helper function 3: Free OCI handles and disconnect */
STATICF sword free_oci_handles(test_ctx *ctx)
{
sword status = 0;
/* End the session */
if (status = OCISessionEnd((OCISvcCtx *)ctx->svchp, (OCIError *)ctx->errhp,
(OCISession *)ctx->sesshp, (ub4) OCI_DEFAULT))
{
if (ctx->envhp)
OCIHandleFree((dvoid *)ctx->envhp, OCI_HTYPE_ENV);
return status;
}
/* Detach from the server */
if (status = OCIServerDetach((OCIServer *)ctx->srvhp, (OCIError *)ctx->errhp,
(ub4)OCI_DEFAULT))
{
if (ctx->envhp)
OCIHandleFree((dvoid *)ctx->envhp, OCI_HTYPE_ENV);
return status;
}
/* Free the handles */
if (ctx->stmthp) OCIHandleFree((dvoid *)ctx->stmthp, (ub4) OCI_HTYPE_STMT);
if (ctx->sesshp) OCIHandleFree((dvoid *)ctx->sesshp, (ub4) OCI_HTYPE_SESSION);
if (ctx->svchp) OCIHandleFree((dvoid *)ctx->svchp, (ub4) OCI_HTYPE_SVCCTX);
if (ctx->srvhp) OCIHandleFree((dvoid *)ctx->srvhp, (ub4) OCI_HTYPE_SERVER);
if (ctx->errhp) OCIHandleFree((dvoid *)ctx->errhp, (ub4) OCI_HTYPE_ERROR);
if (ctx->envhp) OCIHandleFree((dvoid *)ctx->envhp, (ub4) OCI_HTYPE_ENV);
return status;
}

A-52 Oracle XML DB Developer's Guide

B
Oracle XML DB Restrictions
This appendix describes the restrictions associated with Oracle XML DB.
■

■

Thin JDBC Driver Not Supported by Some XMLType Functions – XMLType methods
createXML() with a stream argument, extract(), transform(), and
existsNode() work only with the OCI driver. Not all oracle.xdb.XMLType
functions are supported by the thin JDBC driver. If you do not use
oracle.xdb.XMLType classes and the OCI driver, you can lose performance
benefits.
NCHAR, NVARCHAR, and NCLOB Not Supported – Oracle XML DB does not
support the use of SQL data types NCHAR, NVARCHAR, and NCLOB for any of the
following:
–

Mapping XML elements or attributes to these data types using the SQLType
annotation in an XML schema

–

Generating XML data from these data types using SQL/XML functions
XMLElement, XMLAttributes, and XMLForest

–

Within SQL/XML functions XMLQuery and XMLTable, using XQuery
functions ora:view (deprecated), fn:doc, and fn:collection on tables
that contain columns with these data types

To handle, store, or generate XML data that contains multibyte characters, Oracle
strongly recommends that you use AL32UTF8 as the database character set.
■

■

■

■

■

XML Identifier Length Limit – Oracle XML DB supports only XML identifiers that
are 4000 characters long or shorter.
Repository File Size Limit – The maximum size of a file in Oracle XML DB
Repository is 4 gigabytes. This implies the following limits for different kinds of
file data:
–

4 gigabytes for any LOB, which means 2 gigacharacters for a CLOB stored in
the database character set AL32UTF8.

–

4 gigabytes for binary XML encoded data, which typically means more than 4
gigabytes of external XML data before encoding.

–

Indeterminate for XML data stored object-relationally.

Repository-Wide Resource Configuration File Limit – You cannot create more than 125
resource configuration files for repository-wide configuration.
Recursive Folder Deletion – You cannot delete more than 50 levels of nested folders
using the option for recursive deletion.
No Hybrid Columnar Compression – Hybrid columnar compression, which is
available only for Oracle Exadata Storage Server Software, cannot be used with an
Oracle XML DB Restrictions B-1

XMLType column that is stored object-relationally or with an XMLType table (no
matter which storage model is used). XMLType supports only basic compression
and compression for OLTP.
■

■

■

■

■

No Column-Level Encryption for XMLType – Column-level encryption is not
supported for XMLType. Tablespace-level encryption is supported for all XMLType
storage models.
No Parallel DML for XMLType – DML operations on XMLType data are always
performed in serial. Parallel DML is not supported for XMLType. (Parallel query
and DDL are supported for XMLType.)
No XMLType Access over Database Links – Access to remote XMLType tables or
columns is not supported.
Oracle JVM Needed for Some Features – In general, the behavior of Oracle XML DB
does not depend on whether or not you have Oracle JVM (Java Virtual Machine)
installed. However, if you use Java servlets or PL/SQL package DBMS_XMLSAVE
or DBMS_XMLQUERY then you must install Oracle JVM.
Editioning Views Not Compatible with XMLType – Editioning views are not
compatible with XMLType data that is stored object-relationally. They cannot be
enabled in database schemas that contain persisted object types.
See Also:
■

■

"Oracle XML DB Support for XQuery" on page 5-42 for
information about Oracle XML DB support for XQuery
Oracle Exadata Storage Server Software User's Guide for information
about Oracle Exadata Storage Server

B-2 Oracle XML DB Developer's Guide

Index
A
access control entry (ACE)
definition, 27-3
access control list (ACL)
child
definition, 27-9
constraining inheritance
definition, 27-9
definition, 27-4
extending inheritance
definition, 27-9
overview, 1-7
parent
definition, 27-9
system, 27-7
account XDB, 2-1, 3-68, 3-73, 25-20, 26-2, 27-7, 36-4
ACE
See access control entry
ACL
See access control list
ACLOID resource property
definition, 27-7
administering Oracle XML DB, 34-1
Advanced Queuing (AQ)
IDAP, 37-5
messaging scenarios, 37-1
point-to-point support, 37-1
publish/subscribe support, 37-1
XMLType queue payloads, 37-5
aggregate privilege
definition, 27-3
annotations
XML schema, 3-19, 7-34
querying to obtain, 7-43
anonymous user, access to repository, 28-6
appendChildXML SQL function, 4-30
atomic privilege
definition, 27-3
attribute XML Schema data types
mapping to SQL, 7-47
attributes
Container, 21-6
xdb:columnProps, 7-39
xdb:defaultSchema, 7-9
xdb:defaultTable, 7-35, 7-39

xdb:defaultTableSchema, 7-39
xdb:maintainDOM, 7-17, 7-35, 7-39, 7-41
xdb:maintainOrder, 7-39
xdb:mapUnboundedStringToLob, 7-41
xdb:maxOccurs, 7-39
xdb:SQLCollSchema, 7-40
xdb:SQLCollType, 7-35, 7-40
xdb:SQLInline, 7-40, 9-4, 9-5
xdb:SQLName, 7-35, 7-40
xdb:SQLSchema, 7-40, 7-41
xdb:SQLType, 7-35, 7-40, 7-41, 9-14
xdb:srclang, 7-40
xdb:storeVarrayAsTable, 7-35, 7-41
xdb:tableProps, 7-40
xdb:translate, 7-40
xsi:noNamespaceSchemaLocation, 7-4, 19-8
authenticatedUser role
DBuri servlet security, 20-28

B
backward-compatible XML schema evolution
definition, 10-15
binary XML
definition, 1-15
Schema data types
mapping to SQL, 7-49
bootstrap ACL
definition, 27-7
B-tree index, 1-16

C
C API for XML, 16-1
CharacterData interface, 13-9
CheckIn event, repository, 30-4
CheckOut event, repository, 30-4
child ACL
definition, 27-9
circular dependencies
XML schemas, 9-18
CLASSPATH Java variable
setting, 31-7
CLOB storage of XML data
definition, 1-15
closeContext PL/SQL procedure, 14-2

Index-1

collection
in out-of-line tables, 9-8
loading and retrieving large documents, 9-28
XML
definition, 7-32
collection attribute (SQL), 7-52
columnProps attribute, 7-39
complex XLink link
definition, 23-2
See also extended XLink link
complexType
handling cycles, 9-19
handling inheritance, 9-15
mapping
any and anyAttribute declarations, 9-18
fragments to LOBs, 9-14
XML Schema data types to SQL, 7-52
Oracle XML DB restrictions and extensions, 9-15
component of a resource path name
definition, 21-3
compound XML document, 23-3
definition, 23-1
compression
for online transaction processing (OLTP)
using CREATE TABLE, 7-32
using XML schema annotations, 7-42
XMLType support, 1-19, B-1
configuring Oracle XML DB
protocol server, 28-3
repository, 22-1
servlets, 32-3
using DBMS_XDB API, 34-10
using Oracle Enterprise Manager, 34-4
xdbconfig.xml configuration file, 34-5
constraining inheritance, ACLs
definition, 27-9
constraints on XMLType data, 7-34
repetitive XML elements, 9-3
contains SQL function, 6-4
contains XPath function (Oracle), 12-17
content of a resource
definition, 21-4
Content Repository API for Java
See JCR
content-management application
definition, 23-1
Contents element, 21-5
copy-based XML schema evolution, 10-2
copyEvolve PL/SQL procedure, 10-1
COST_XML_QUERY_REWRITE optimizer
hint, 5-31
cost-based XML query rewrite
definition, 5-31
Create event, repository, 30-3
CREATE TABLE statement
encoding options for binary XML, 7-31
logging, 7-9
storage options, 7-30
XMLType, 3-3
storage as CLOB, 7-32

Index-2

CREATE TYPE statement
logging, 7-9
createResource PL/SQL function, 3-10
createXML() XMLType method, 13-2, 15-2
creating an XMLType table, 3-3
for nested collections, 3-29
storage options, 7-29
XML schema-based, 3-28, 7-27
CTXCAT index, 12-13
CTXRULE index, 12-13
cyclical dependencies
XML schemas, 9-18

D
database role
definition, 27-2
database user
definition, 27-2
data-centric use of XML data
definition, 1-15
date and time XML Schema data types
mapping to SQL, 7-50
DAV: WebDAV namespace, 27-5
DBMS_METADATA PL/SQL package, 20-3
reference documentation, 1-5
DBMS_XDB PL/SQL package, 26-1
reference documentation, 1-5
DBMS_XDB_ADMIN PL/SQL package
reference documentation, 1-5
DBMS_XDB_VERSION PL/SQL package, 24-1
reference documentation, 1-5
DBMS_XDBT PL/SQL package, 1-5
DBMS_XDBZ PL/SQL package, 29-13
disable_hierarchy procedure, 27-19
enable_hierarchy procedure, 27-19
is_hierarchy_enabled function, 29-13
purgeLDAPCache procedure, 27-18
reference documentation, 1-5
DBMS_XEVENT PL/SQL package
reference documentation, 1-5
DBMS_XMLDOM PL/SQL package, 13-3
examples, 13-10
reference documentation, 1-5
DBMS_XMLGEN PL/SQL package, 18-21
reference documentation, 1-5
DBMS_XMLINDEX PL/SQL package
modifyParameter procedure, 6-39
reference documentation, 1-5
registerParameter procedure, 6-39
DBMS_XMLPARSER PL/SQL package, 13-19
reference documentation, 1-5
DBMS_XMLQUERY PL/SQL package
Oracle Java Virtual Machine dependency, B-2
DBMS_XMLSAVE PL/SQL package, 14-1
Oracle Java Virtual Machine dependency, B-2
DBMS_XMLSCHEMA PL/SQL package, 7-6
copyEvolve procedure, 10-1
deleteSchema procedure, 7-12
generateSchema and generateSchemas

functions, 9-1
inPlaceEvolve procedure, 10-1
mapping types, 7-45
purgeSchema procedure, 7-13
reference documentation, 1-6
registerSchema procedure, 7-7, 9-28
enableHierarchy parameter, 29-3
DBMS_XMLSTORE PL/SQL package, 14-1
reference documentation, 1-6
DBMS_XSLPROCESSOR PL/SQL package, 13-20
reference documentation, 1-6
DBUri
definition, 20-2
generating using sys_DburiGen SQL
function, 20-22
identifying a row, 20-17
identifying a target column, 20-17
retrieving column text value, 20-18
retrieving the whole table, 20-16
security, 20-28
servlet, installation, 20-27
DBUri-refs, 20-12
HTTP access, 20-26
DBUriServlet
definition, 20-26
DBURIType
definition, 20-2
debugging
XML schema registration, 7-9
default tables
creating during XML schema registration, 7-10
defaultSchema attribute, 7-9
defaultTable attribute, 7-35, 7-39
defaultTableSchema attribute, 7-39
Delete event, repository, 30-3
deleteSchema PL/SQL procedure, 7-12
deleteXML PL/SQL function, 14-1
deleteXML SQL function, 4-31
deleting
resource, 25-14
XML schema using DBMS_XMLSCHEMA, 7-12
depth SQL function, 25-8
derived XML Schema data types
mapping to SQL, 7-50
directory
See folder
disable_hierarchy PL/SQL procedure, 27-19
document (DOM)
definition, 13-8
document link
definition, 21-7, 23-2
obtaining information about, 23-7
document location hint
definition, 3-24
Document Object Model
See DOM
Document Type Definition
See DTD
document view serialization, JCR
definition, 31-5

DOCUMENT_LINKS public view, 23-7
document-centric use of XML data
definition, 1-16
document-correlated recursive query
definition, 9-25
DOM
definition, 13-1
difference from SAX, 13-4
document
definition, 13-8
fidelity, 7-16
for XML schema mapping, 13-7
SYS_XDBPD$ object attribute, 7-16
using SQL function updateXML, 4-20
Java API for XMLType, 15-1
NamedNodeMap object, 13-9
NodeList object, 13-9
overview, 13-3
PL/SQL API for XMLType, 13-3
DOM fidelity
definition, 7-16
DTD
definition, 7-6
support in Oracle XML DB, 7-6
use with Oracle XML DB, 7-5
dynamic type-checking
XQuery language, 5-37

E
effective text value of a node
definition, 6-16
element XML Schema data types
mapping to SQL, 7-47
elements
Contents, Resource index, 21-5
XDBBinary, 21-11
enable_hierarchy PL/SQL procedure, 27-19
enableHierarchy parameter, DBMS_
XMLSCHEMA.registerSchema, 29-3
Enterprise Manager
administering Oracle XML DB, 34-4
entities, XML
using a DTD with binary XML storage, 7-5
equals_path SQL function, 5-36, 25-7
equipartitioning of XMLType tables
definition, 9-10
event
repository, 30-1
configuring, 30-8
predefined, 30-3
event handler, repository
definition, 30-2
event listener, repository
definition, 30-2
evolution, XML schema, 10-1
existsNode Oracle SQL function (deprecated), lii
extended XLink link
definition, 23-2
extending inheritance, ACLs

Index-3

definition, 27-9
extract Oracle SQL function (deprecated), lii
extracting data from XML, 4-7
extractValue Oracle SQL function (deprecated), lii

generateSchema and generateSchemas, 9-1
insertXML, 14-1
is_hierarchy_enabled, 29-13
updateXML, 14-1
SQL
appendChildXML, 4-30
contains, 6-4
deleteXML, 4-31
depth, 25-8
equals_path, 5-36, 25-7
existsNode (deprecated), lii
extract (deprecated), lii
extractValue (deprecated), lii
insertChildXML, 4-23
insertChildXMLafter, 4-26
insertChildXMLbefore, 4-25
insertXMLafter, 4-29
insertXMLbefore, 4-27
path, 25-7
sys_DburiGen, 20-22
sys_XMLAgg, 18-54
sys_XMLGen, 18-46
under_path, 25-5
updateXML, 4-14
updating XML data, 4-10
XMLAgg, 18-12
XMLAttributes, 18-3
XMLCast, 4-4
XMLCDATA, 18-21
XMLColAttVal, 18-19
XMLComment, 18-16
XMLConcat, 18-11
XMLElement, 18-3
XMLExists, 4-3
XMLForest, 18-9
XMLIsValid, 3-33, 11-7
XMLParse, 18-17
XMLPI, 18-15
XMLQuery, 5-5, 5-6
XMLRoot, 18-18
XMLSequence (deprecated), lii
XMLSerialize, 18-16
XMLTable, 5-5, 5-7
XMLtransform, 11-2
XPath
ora:instanceof (deprecated), lii
ora:instanceof-only (deprecated), li, lii

F
fidelity
DOM, 7-16
for XML schema mapping, 13-7
SYS_XDBPD$ object attribute, 7-16
using SQL function updateXML, 4-20
FLWOR XQuery expression, 5-4
fn:available
support, 5-43
fn:collection
avoiding to improve performance, 5-36
support, 5-43
fn:doc
avoiding to improve performance, 5-36
support, 5-43
fn:id
support, 5-43
fn:idref
support, 5-43
fn:matches
support, 5-43
fn:replace
support, 5-43
fn:tokenize
support, 5-43
folder
definition, 21-3
folder link
definition, 21-7
folder sys, repository, 21-2
foldering, 21-1
folder-restricted query
definition, 3-82
fragment, XML
definition, 3-46
SQL operations on, 3-46
fragments, XML
mapping to LOBs, 9-14
freeDocument PL/SQL procedure, 13-10
freeing a DOMdocument instance, 13-10
FROM list order
XMLTable PASSING clause, 5-25
FTP
configuration parameters, 28-4
creating default tables, 7-10
protocol server, features, 28-8
fully qualified XML schema URLs, 9-13
functional evaluation
definition, 3-58
function-based index, 6-5
functions
PL/SQL
createResource, 3-10
deleteXML, 14-1

Index-4

G
gatherRepositoryStats PL/SQL procedure, 26-2
generateSchema and generateSchemas PL/SQL
functions, 9-1
generating XML, 18-1
DBMS_XMLGEN PL/SQL package, 18-21
DBMS_XMLSCHEMA PL/SQL package, 9-1
generateSchema and generateSchemas PL/SQL
functions, 9-1
SQL functions, 18-1
sys_XMLAgg SQL function, 18-54

sys_XMLGen SQL function, 18-46
XML schemas, 9-1
XMLAgg SQL function, 18-12
XMLAttributes SQL function, 18-3
XMLCDATA SQL function, 18-21
XMLColAttVal SQL function, 18-19
XMLComment SQL function, 18-16
XMLConcat SQL function, 18-11
XMLElement SQL function, 18-3
XMLForest SQL function, 18-9
XMLParse SQL function, 18-17
XMLPI SQL function, 18-15
XMLRoot SQL function, 18-18
XMLSerialize SQL function, 18-16
getBLOBVal() Oracle XMLType method
(deprecated), lii
getCLOB() XMLType method, 15-12
getCLOBVal() Oracle XMLType method
(deprecated), lii
getNamespace() Oracle XMLType method
(deprecated), lii
getNumberVal() XMLType method, 4-2
getObject() XMLType method, 15-3
getOPAQUE() XMLType method, 15-2
getRootElement() Oracle XMLType method
(deprecated), lii
getSchemaURL() XMLType method, 7-14
getStringVal() Oracle XMLType method
(deprecated), lii
getting JCR repository objects, 31-7
global XML schema
definition, 7-15
using fully qualified URL to override, 9-13
grants declared in an ACL
definition, 27-9
grants defined for an ACL
definition, 27-9
group in an XMLIndex structured component
definition, 6-23

H
hard link
definition, 21-7
JCR, 31-6
hierarchical repository index, 3-86
hierarchy-enabled table
definition, 27-19
HTTP
access for DBUri-refs, 20-26
accessing Java servlet or XMLType, 32-2
accessing repository resources, 21-11
configuration parameters, WebDAV, 28-5
creating default tables, 7-10
improved performance, 28-2
Oracle XML DB servlets, 32-6
protocol server, features, 28-14
requests, 32-6
servlets, 32-2
URIFACTORY, 20-29

using UriRefs to store pointers, 20-3
HTTPUri
definition, 20-2
HTTPURIType
definition, 20-2
hybrid columnar compression, B-1
hybrid storage
definition, 6-4
hybrid storage of XML data
definition, 1-15

I
IDAP
architecture, 37-5
transmitted over Internet, 37-5
IMPORT/EXPORT
in XML DB, 36-3
index
hierarchical repository, 3-86
indexing
CTXCAT, 12-13
CTXRULE, 12-13
function-based, 6-5
options for XMLType, 3-3
Oracle Text, 1-27, 6-46, 12-1
XMLType, 6-3
index-organized tables, 3-19
inheritance
XML schema, restrictions in complexTypes, 9-16
in-place XML schema evolution, 10-15
inPlaceEvolve PL/SQL procedure, 10-1
insertChildXML SQL function, 4-23
insertChildXMLafter SQL function, 4-26
insertChildXMLbefore SQL function, 4-25
insertXML PL/SQL function, 14-1
insertXML() XMLType method, 15-11
insertXMLafter SQL function, 4-29
insertXMLbefore SQL function, 4-27
installing Oracle XML DB, 34-1
instance document
definition, 1-14
specifying root element namespace, 7-4
Internet Data Access Presentation (IDAP)
SOAP specification for AQ, 37-5
Internet Protocol Version 6
FTP, 28-13
HTTP(S), 28-16
IPv6
FTP, 28-13
HTTP(S), 28-16
is_hierarchy_enabled PL/SQL function, 29-13
isSchemaBased() XMLType method, 7-14
IsSchemaValid() XMLType method, 11-7
isSchemaValid() XMLType method, 7-14
isSchemaValidated() XMLType method, 7-14, 11-7

J
Java
connections, thick and thin,

15-13
Index-5

DOM API for XMLType, 15-1
Oracle XML DB applications, 32-1
oracle.xml.parser.v2, 15-1
Java Content Repository API
See JCR
JCR
compliance levels supported, 31-10
document view serialization
definition, 31-5
files and folders, exposure, 31-3
getPath() Java method, 31-6
hard link, 31-6
logging, 31-9
Oracle XML DB Repository access, 31-2
overview, 31-1
restrictions for Oracle XML DB Content
Connector, 31-10
weak link, 31-6
XML schema, 31-11
JCR node types
mapping from XML Schema data types, 31-14
mapping from XML Schema global element
declarations, 31-17
nt:file, 31-2
nt:folder, 31-2
Oracle extensions, 31-5
jcr:content, 31-6
jcr:data property, 31-5
JDBC
accessing XML documents, 15-2
drivers, OCI and thin, 15-4
loading large XML documents, 15-11
manipulating XML documents, 15-4
JSR-170
See JCR 1.0

L
large node handling, 13-12
lazy XML loading (lazy manifestation), 13-2
link
document
definition, 21-7
folder
definition, 21-7
hard
definition, 21-7
repository
definition, 21-7
weak
definition, 21-7
link name
definition, 21-4
LinkIn event, repository, 30-4
linking, repository
definition, 3-81
link-properties document
definition, 3-81
LinkTo event, repository, 30-4
loading

Index-6

large documents with collections, 9-28
loading large XML documents using JDBC, 15-11
loading of XML data, lazy, 13-2
LOB locator, 24-6
LOBs
mapping XML fragments to, 9-14
local XML schema
definition, 7-14
using fully qualified URL to specify, 9-13
Lock event, repository, 30-4

M
maintainDOM attribute, 7-17, 7-35, 7-39, 7-41
maintainOrder attribute, 7-39
manifestation, lazy, 13-2
mapping
complexType any and anyAttributes
declarations, 9-18
complexType to SQL
out-of-line storage, 9-4
overriding using SQLType attribute, 7-48
simpleContent to object types, 9-17
mapping XML Schema complexType data types to
SQL, 7-52
mapping XML Schema data types to SQL data
types, 7-45
mapping XML Schema to SQL
simpleType, 7-48
mapUnboundedStringToLob attribute, 7-41
matches XQuery function (Oracle), 5-12
maxOccurs attribute, 7-39
metadata
definition, 29-1
system-defined
definition, 1-7
user-defined
definition, 1-7
methods
XMLType
createXML(), 13-2, 15-2
getBLOBVal() (deprecated), lii
getCLOB(), 15-12
getCLOBVal() (deprecated), lii
getNamespace() (deprecated), lii
getNumberVal(), 4-2
getObject(), 15-3
getOPAQUE(), 15-2
getRootElement() (deprecated), lii
getSchemaURL(), 7-14
getStringVal() (deprecated), lii
insertXML(), 15-11
isSchemaBased(), 7-14
IsSchemaValid(), 11-7
isSchemaValid(), 7-14
isSchemaValidated(), 7-14, 11-7
schemaValidate(), 7-14
setObject(), 15-4
setSchemaValidated(), 7-14, 11-7
writeToStream(), 21-12

XML schema, 7-14
MIME
overriding with DBUri servlet, 20-27
mix:referenceable, 31-5
mixed XML content
definition, 1-16
model, XML Schema
definition, 10-16
modifyParameter PL/SQL procedure, 6-39

N
NamedNodeMap object (DOM), 13-9
namespace
prefixes
ocjr, 31-5
URL for XML schema, 7-4
XQuery, 5-9, 5-27
naming SQL objects, 7-34
navigational access to repository resources, 21-9
nested XML
generating using DBMS_XMLGEN, 18-32
generating with XMLElement, 18-6
NESTED_TABLE_ID pseudocolumn, 3-28
newDOMDocument() function, 13-9
NodeList object (DOM), 13-9
nodes, large (DBMS_XMLDOM), 13-12
nodes, large (Java), 15-16
noNamespaceSchemaLocation attribute, 7-4, 19-8
non-schema-based view
definition, 19-1
nt:file JCR node type, 31-2
nt:folder, 31-2
nt:folder JCR node type, 31-2
numeric XML Schema data types
mapping to SQL, 7-49

O
object attributes
for collection (SQL), 7-52
of XMLFormat, 18-47
REF, 9-5, 9-20
sys_DburiGen SQL function
passing to, 20-23
SYS_XDBPD$, 7-16
XMLType, in AQ, 37-5
object identifier
definition, 27-7
OBJECT_ID column of XDB$ACL table,
object-based persistence of XML data
definition, 1-15
object-relational storage of XML data
definition, 1-15
occurrence indicator
definition, 5-4
OCI API for XML, 16-1
ocjr namespace prefix, 31-5
OCT
definition, 3-19
ODP.NET, 17-1

27-7

OID
See object identifier
ojcr:folder, 31-5
operator
See functions, SQL
optimizer hints
COST_XML_QUERY_REWRITE, 5-31
optimizing repository queries, 26-2
ora:contains XPath function (Oracle), 12-17
policy
definition, 12-18
ora:defaultTable XQuery pragma, 5-14, 5-36
ora:instanceof Oracle XPath function
(deprecated), lii
ora:instanceof-only Oracle XPath function
(deprecated), li, lii
ora:invalid_path XQuery pragma, 5-14
ora:matches XQuery function (Oracle), 5-12
ora:replace XQuery function (Oracle), 5-12
ora:sqrt XQuery function (Oracle), 5-13
ora:tokenize XQuery function (Oracle), 5-13
ora:view_on_null XQuery pragma, 5-14
ora:xq_proc XQuery pragma, 5-14, 6-30
ora:xq_qry XQuery pragma, 5-14
Oracle ASM files
accessing, 21-12
using FTP, 28-11
Oracle ASM virtual folder, 21-6
Oracle Data Provider for .NET, 17-1
Oracle Enterprise Manager
administering Oracle XML DB, 34-4
Oracle extensions to JCR node types, 31-5
Oracle Internet Directory, 27-20
Oracle Net Services, 1-2
Oracle Text
contains SQL function and XMLType, 6-4
index, 1-27, 6-46, 12-1
searching for resources, 25-20
searching XML in CLOB instances, 1-27
Oracle XML DB
access models, 2-3
advanced queuing, 1-27
architecture, 1-2
features, 1-12
installation, 34-1
Java applications, 32-1
overview, 1-1
Repository
See repository
upgrading, 34-3
versioning, 24-1
when to use, 2-1
Oracle XML DB Content Connector, 31-1
how to use, 31-7
logging API, 31-9
overview, 31-2
restrictions, 31-10
sample code to upload file, 31-8
See also JCR
OracleRepository, 31-7

Index-7

oracle.xdb.XMLType Java class, 15-1, 15-14
oracle.xml.parser.v2 Java package, 15-1
order index of XMLIndex
definition, 6-13
ordered collection
definition, 3-19
ordered collection table (OCT)
definition, 3-19
ordered collections in tables (OCTs)
default storage of varray, 7-52
out-of-line storage, 9-4
collections, 9-8
XPath rewrite, 9-7

P
parent ACL
definition, 27-9
partial update of XML data
definition, 4-12
partial validation of XML data
definition, 3-32
partitioning XMLType tables, 9-10
binary XML, 3-3
PASSING clause of XMLTable
FROM list order, 5-25
path component of a resource path name
definition, 21-3
path index of XMLIndex
definition, 6-13
path name
definition, 21-3
resolution, 21-6
path SQL function, 25-7
path table of XMLIndex, 6-13
PATH_VIEW, 25-1
path-based access to repository resources, 21-9
path-index trigger
definition, 27-19
PD (positional descriptor), 7-17
persistence models for XML data, 1-14
PL/SQL functions
See functions, PL/SQL
PL/SQL packages
DBMS_METADATA, 20-3
reference documentation, 1-5
DBMS_XDB, 26-1
reference documentation, 1-5
DBMS_XDB_ADMIN
reference documentation, 1-5
DBMS_XDB_VERSION, 24-1
reference documentation, 1-5
DBMS_XDBT, 1-5
DBMS_XDBZ, 27-19, 29-13
reference documentation, 1-5
DBMS_XEVENT
reference documentation, 1-5
DBMS_XMLDOM, 13-3
reference documentation, 1-5
DBMS_XMLGEN, 18-21

Index-8

reference documentation, 1-5
DBMS_XMLINDEX
reference documentation, 1-5
DBMS_XMLPARSER, 13-19
reference documentation, 1-5
DBMS_XMLQUERY
Oracle Java Virtual Machine dependency, B-2
DBMS_XMLSAVE, 14-1
Oracle Java Virtual Machine dependency, B-2
DBMS_XMLSCHEMA
reference documentation, 1-6
See DBMS_XMLSCHEMA PL/SQL package
DBMS_XMLSTORE, 14-1
reference documentation, 1-6
DBMS_XSLPROCESSOR, 13-20
reference documentation, 1-6
for XMLType, 13-1
PL/SQL procedures
See procedures, PL/SQL
point-to-point
support in AQ, 37-1
policy for ora:contains XPath function (Oracle)
definition, 12-18
ports
configuring
FTP, 28-4
HTTP, 28-5
HTTPS, 28-6
positional descriptor (PD), 7-17
post-parse persistence of XML data
definition, 1-15
pragmas
XQuery
Oracle, 5-13
predefined ACLs, 27-7
preference
Oracle Text indexing
definition, 12-13
pretty-printing, 18-17
in book examples, xlvi
not done by SQL/XML functions, 3-60
Web service output, 33-5
primitive XML Schema data types
mapping to SQL, 7-50
principal
definition, 27-2
private (local) XML schema, definition, 7-14
privilege
definition, 27-3
procedures
PL/SQL
closeContext, 14-2
copyEvolve, 10-1
disable_hierarchy, 27-19
enable_hierarchy, 27-19
freeDocument, 13-10
gatherRepositoryStats, 26-2
inPlaceEvolve, 10-1
modifyParameter, 6-39
processXSL, 13-22

purgeLDAPCache, 27-18
registerParameter, 6-39
registerSchema, 7-7
setKeyColumn, 14-2
setUpdateColumn, 14-2
processXSL PL/SQL procedure, 13-22
protocol server, 28-1
architecture, 28-2
configuration parameters, 28-3
event-based logging, 28-8
FTP, 28-8
configuration parameters, 28-4
HTTP, 28-14
configuration parameters, 28-5
WebDAV, 28-20
configuration parameters, 28-5
protocols, access to repository resources, 21-10
public (global) XML schema, definition, 7-14
publish/subscribe
support in AQ, 37-1
purchase-order XML document
used in full-text examples, 12-26
purchase-order XML schema, 3-14
annotated, 3-20, A-30
graphical representation, 3-17
revised, 10-2, A-33
purgeLDAPCache PL/SQL procedure, 27-18
purgeSchema PL/SQL procedure, 7-13

Q
qualified XML schema URLs, 9-13
query-based access to resources
using RESOURCE_VIEW and PATH_VIEW, 25-2
using SQL, 21-13
querying XMLType data
choices, 4-1
transient data, 4-7

R
ra:use_text_index Oracle XQuery pragma, 12-25
recursive schema support, 9-24
REF object attribute, 9-5, 9-20
REGISTER_NT_AS_IOT option for XML schema
registration, 3-19, 7-7
registered XML schemas, list of, 7-11
registering an XML schema, 7-7
debugging, 7-9
default tables, creating, 7-10
SQL object types, creating, 7-9
registering an XML schema for JCR, 31-11
registerParameter PL/SQL procedure, 6-39
registerSchema PL/SQL procedure, 7-7
renaming an XMLIndex index, 6-18
Render event, repository, 30-3
replace XQuery function (Oracle), 5-12
repository, 21-3
access by anonymous user, 28-6
access using JCR, 31-2
data storage, 21-5

event, 30-1
configuring, 30-8
predefined, 30-3
event handler
definition, 30-2
event listener
definition, 30-2
hierarchical index, 3-86
resource
See resource
use with XQuery, 5-16
repository link
definition, 21-7
repository objects, 31-7
RESID
definition, 24-2
resource
access, 21-3
using protocols, 28-7
definition, 1-7, 29-1
deleting, 21-7
nonempty container, 25-15
using DELETE, 25-14
managing with DBMS_XDB, 26-1, 34-13
required privileges for operations, 27-4
searching for, using Oracle Text, 25-20
setting property in ACLs, 27-11
simultaneous operations, 25-18
updating, 25-15
resource configuration file
definition, 22-1
resource configuration list
definition, 22-2
resource content
definition, 21-4
resource document
definition, 3-73
resource ID
definition, 24-2
resource name
definition, 21-4
resource version
definition, 24-2
RESOURCE_VIEW
explained, 25-1
resource-view-cache-size configuration
parameter, 25-20
retrieving large documents with collections, 9-28
rewrite
XPath (XPath), 8-1
XQuery, 5-29
role
authenticatedUser, DBuri servlet, 20-28
database
definition, 27-2
XDB_SET_INVOKER, 30-8
XDBADMIN, 7-15, 22-2, 27-7, 30-8
root folder, repository, 21-1
root XML Schema
definition, 7-9

Index-9

rule-based XML query rewrite
definition, 5-31

S
scalar value
converting to XML document using sys_
XMLGen, 18-48
schema evolution
See XML schema evolution
schema for schemas (XML Schema)
definition, 1-13
schema location hint
definition, 3-24
schemaValidate() XMLType method, 7-14
searching CLOB instances, 1-27
security
DBUri, 20-28
semi-structured XML data
definition, 1-16
servlets
accessing repository data, 21-14
APIs, 32-7
configuring, 32-3
session pooling, 32-7
writing, 32-7
in Java, 32-2
XML manipulation, 32-2
session pooling, 32-7
protocol server, 28-2
setKeyColumn PL/SQL procedure, 14-2
setObject() XMLType method, 15-4
setSchemaValidated() XMLType method, 7-14, 11-7
setUpdateColumn PL/SQL procedure, 14-2
simple XLink link
definition, 23-2
simpleContent
mapping to object types, 9-17
simpleType XML Schema data types
mapping to SQL, 7-48
SOAP, 33-1
access through Advanced Queuing, 1-2
IDAP, 37-5
SQL function
See functions, SQL
SQL functions
See functions, SQL
SQL object types
creating during XML schema registration, 7-9
SQL operator
See functions, SQL
SQL*Loader, 35-1
SQL*Plus
XQUERY command, 5-38
SQLCollSchema attribute, 7-40
SQLCollType attribute, 7-35, 7-40
SQLInline attribute, 7-40, 9-4, 9-5
SQLJ, 15-14
SQLName attribute, 7-35, 7-40
SQLSchema attribute, 7-40, 7-41

Index-10

SQLType attribute, 7-35, 7-40, 7-41, 9-14
SQL/XML generation functions
definition, 1-20
SQL/XML publishing functions
definition, 1-20, 18-2
SQL/XML query and access functions
definition, 1-20
SQL/XML standard
generating XML data, 18-2
querying XML data
XMLExists and XMLCast, 4-2
XMLQuery and XMLTable, 5-5
sqrt XQuery function (Oracle), 5-13
srclang attribute, 7-40
standard metadata, 31-5
static type-checking
XQuery language, 5-37
storage
out of line, 9-4
collections, 9-8
XMLType, CREATE TABLE, 7-32
storage models for XMLType, 1-14
storeVarrayAsTable attribute, 7-35, 7-41
string XML Schema data types
mapping to SQL, 7-49
mapping to VARCHAR2 vs CLOB, 7-51
structured storage of XML data
definition, 1-15
structured XMLIndex component
definition, 6-9
style sheet for updating XML instance
documents, 10-10
sys folder, repository, 21-2
sys_DburiGen SQL function, 20-22
inserting database references, 20-24
retrieving object URLs, 20-25
use with text node test, 20-23
SYS_NC_ARRAY_INDEX$ column, 3-28
SYS_XDBPD$ object attribute, 7-16
sys_XMLAgg SQL function, 18-54
sys_XMLGen SQL function, 18-46
converting XMLType instances, 18-51
object views, 18-52
XMLFormat object attributes, 18-47
XMLGenFormatType object, 18-47
SYSAUX tablespace, 34-1
system ACL
definition, 27-7
system ACLs, 27-7
system-defined metadata
definition, 1-7

T
tableProps attribute, 7-40
tables
index-organized, 3-19
tablespace
SYSAUX, 34-1
text value of a node, effective

definition, 6-16
text-based persistence of XML data
definition, 1-15
third-party XLink link
definition, 23-2
tokenize XQuery function (Oracle), 5-13
translate attribute, 7-40
trigger, path-index
definition, 27-19
type-checking, static and dynamic
XQuery language, 5-37

U
UDT
generating an element from, 18-8
UncheckOut event, repository, 30-4
under_path SQL function, 25-5
uniform access control mechanism
definition, 27-19
unique constraint on parent element of an
attribute, 9-3
UnLinkIn event, repository, 30-4
Unlock event, repository, 30-4
unresolved XLink and XInclude links, 23-9
unstructured storage of XML data
definition, 1-15
unstructured XMLIndex component
definition, 6-9
Update event, repository, 30-4
updateXML PL/SQL function, 14-1
updateXML SQL function, 4-14
mapping NULL values, 4-18
updating repository resource, 25-15
updating XML data
partial update
definition, 4-12
updating same node more than once, 4-20
using SQL functions, 4-10
optimization, 4-20
upgrading Oracle XML DB, 34-3
URIFACTORY PL/SQL package
configuring to handle DBURI-ref, 20-29
creating subtypes of URIType, 20-20
Uri-reference
database and session, 20-15
DBUri-ref, 20-12
HTTP access for DBUri-ref, 20-26
URIFACTORY PL/SQL package, 20-20
URIType examples, 20-8
URIType
examples, 20-8
user
definition, 27-2
user XDB, 2-1, 3-68, 3-73, 25-20, 26-2, 27-7, 36-4
user-defined metadata, 31-6
definition, 1-7

V
validating

examples, 11-8
IsSchemaValid() XMLType method, 11-7
isSchemaValidated() XMLType method, 11-7
setSchemaValidated() XMLType method, 11-7
XMLIsValid SQL function, 11-7
use as CHECK constraint, 3-33
validation of XML data, partial
definition, 3-32
value index of XMLIndex
definition, 6-13
varray in a LOB
definition, 3-19
varray in a table
definition, 3-19
VCR
See version-controlled resource
version resource
definition, 24-2
version series of a resource
definition, 24-3
versionable resource
definition, 24-2
VersionControl event, repository, 30-4
version-controlled resource
definition, 24-2
versioning, 1-7, 24-1
views
RESOURCE and PATH, 25-1

W
weak link
definition, 21-7
deletion, 23-9
JCR, 31-6
Web service, 33-1
pretty-printing output, 33-5
WebDAV protocol server, 28-20
WebFolder
creating in Windows 2000, 28-22
well-formed XML document
definition, 3-31
writeToStream() XMLType method, 21-12
WSDL
Web service for accessing stored PL/SQL,
Web service for database queries, 33-3

33-6

X
XDB database schema (user account), 2-1, 3-68, 3-73,
25-20, 26-2, 27-7, 36-4
xdb namespace, 27-5
XDB_SET_INVOKER role, 30-8
xdb:columnProps attribute, 7-39
xdb:defaultSchema attribute, 7-9
xdb:defaultTable attribute, 7-35, 7-39
xdb:defaultTableSchema attribute, 7-39
xdb:maintainDOM attribute, 7-17, 7-35, 7-39, 7-41
xdb:maintainOrder attribute, 7-39
xdb:mapUnboundedStringToLob attribute, 7-41
xdb:maxOccurs attribute, 7-39
Index-11

xdb:SQLCollSchema attribute, 7-40
xdb:SQLCollType attribute, 7-35, 7-40
xdb:SQLInline attribute, 7-40, 9-4, 9-5
xdb:SQLName attribute, 7-35, 7-40
xdb:SQLSchema attribute, 7-40, 7-41
xdb:SQLType attribute, 7-35, 7-40, 7-41, 9-14
xdb:srclang attribute, 7-40
xdb:storeVarrayAsTable attribute, 7-35, 7-41
xdb:tableProps attribute, 7-40
xdb:translate attribute, 7-40
XDB$ACL table, 27-7
XDBADMIN role, 7-15, 22-2, 27-7, 30-8
XDBBinary element, 21-11
definition, 21-4
xdbconfig.xml configuration file, 34-5
xdbcore parameters, 9-29
xdbcore-loadableunit-size configuration
parameter, 9-29, 25-20
xdbcore-xobmem-bound configuration
parameter, 9-29, 25-20
XDBUri, 20-3
definition, 20-3, 20-10
XDBURIType
definition, 20-3
using constructor to expand compound documents
(XInclude), 23-5
XInclude, 23-1
definition, 23-1
unresolved link, 23-9
XLink, 23-1
complex link
definition, 23-2
definition, 23-1
extended link
definition, 23-2
link types, 23-2
simple link
definition, 23-2
third-party link
definition, 23-2
unresolved link, 23-9
XML attributes
See attributes
XML diagnosability mode, 5-35
XML entities
using a DTD with binary XML storage, 7-5
XML fragment
definition, 3-46
mapping to LOBs, 9-14
SQL operations on, 3-46
XML instance document
definition, 1-14
XML Object (XOB), 2-7
XML query rewrite
definition, 5-29
cost-based, 5-31
rule-based, 5-31
XML Schema
definition, xlv
XML schema

Index-12

annotations, 3-19, 7-34
querying to obtain, 7-43
circular dependencies, 9-18
complexType declarations, 9-15, 9-19
cyclical dependencies, 9-18
definition, 1-13, 7-2
deletion, 7-12
evolution, 10-1
backward-compatible, definition, 10-15
for XML schemas that can be registered, 7-9
generating from object-relational type, 9-1
inheritance in, complexType restrictions, 9-16
local and global, 7-14
managing and storing, 7-9
mapping to SQL object types, 13-6
registration with Oracle XML DB, 7-7
for use with JCR, 31-11
updating after registering, 10-1
URLs, 9-13
use with JCR, 31-11
use with Oracle XML DB, 7-5
W3C Recommendation, 3-13, 7-1
XMLType methods, 7-14
XML Schema data types
mapping to JCR node types, 31-14
mapping to SQL data types, 7-45
XML schema definition
definition, 1-13
XML schema evolution
copy-based, 10-2
in-place, 10-15
XML schema-based tables and columns,
creating, 7-27
XML schema-based view
definition, 19-1
XML_DB_EVENTS parameter, 30-8
XMLAgg SQL function, 18-12
XMLAttributes SQL function, 18-3
XMLCast SQL function, 4-4
XMLCDATA SQL function, 18-21
XMLColAttVal SQL function, 18-19
XMLComment SQL function, 18-16
XMLConcat SQL function, 18-11
XMLElement SQL function, 18-3
XMLExists SQL function, 4-3
XMLEXTRA object column, 9-22
XMLForest SQL function, 18-9
XMLFormat
XMLAgg, 18-12, 18-54
XMLFormat object type
sys_XMLGen
XMLFormatType object, 18-47
XMLGenFormatType object, 18-47
XMLIndex
creating index, 6-18
dropping index, 6-18
order index
definition, 6-13
path index
definition, 6-13

path table, 6-13
renaming index, 6-18
structured component
definition, 6-9
unstructured component
definition, 6-9
value index
definition, 6-13
XMLIsValid SQL function, 3-33, 11-7
XMLOptimizationCheck SQL*Plus setting, 5-35
XMLOptimizationCheck SQL*Plus system
variable, 0-l, 5-35
XMLParse SQL function, 18-17
XMLPI SQL function, 18-15
XMLQuery SQL function, 5-5, 5-6
XMLRoot SQL function, 18-18
XMLSequence Oracle SQL function (deprecated), lii
XMLSerialize SQL function, 18-16
XMLTable SQL function, 5-5, 5-7
breaking up an XML fragment, 3-46
breaking up multiple levels of XML data, 3-49
PASSING clause and FROM list order, 5-25
XMLtransform SQL function, 11-2
XMLType
as abstract data type, 1-14
benefits, 3-2
constructors, 3-5
contains SQL function, 6-4
CREATE TABLE statement, 7-32
DBMS_XMLDOM PL/SQL API, 13-3
DBMS_XMLPARSER PL/SQL API, 13-19
DBMS_XSLPROCESSOR PL/SQL API, 13-20
definition, 1-12
extracting data, 4-7
indexing columns, 6-3
instances, PL/SQL APIs, 13-1
loading data, 35-1
loading with SQL*Loader, 35-1
methods
createXML(), 13-2, 15-2
getCLOB(), 15-12
getNumberVal(), 4-2
getObject(), 15-3
getOPAQUE(), 15-2
getSchemaURL(), 7-14
insertXML(), 15-11
isSchemaBased(), 7-14
IsSchemaValid(), 11-7
isSchemaValid(), 7-14
isSchemaValidated(), 7-14, 11-7
schemaValidate(), 7-14
setObject(), 15-4
setSchemaValidated(), 7-14, 11-7
writeToStream(), 21-12
XML schema, 7-14
PL/SQL packages, 13-1
querying, 4-1
querying transient data, 4-7
querying XMLType columns, 4-7
queue payloads, 37-5

storage models, 1-14
table, querying with JDBC, 15-2
tables, views, columns, 7-27
views, access with PL/SQL DOM APIs, 13-7
XOB, 2-7
XPath language
functions
ora:contains (Oracle), 5-11, 12-17
syntax, 4-2
See also XQuery language
XPath rewrite, 8-1
definition, 5-29
indexes on singleton elements and attributes, 6-6
out-of-line storage, 9-7
XQuery
extension expressions, 5-13
pragmas
Oracle, 5-13
pragmas, Oracle
ora:use_text_index, 12-25
XQUERY command, SQL*Plus, 5-38
XQuery functions and operators
support, 5-43
XQuery language, 5-1
expressions, 5-3
FLWOR, 5-4
rewrite, 5-29
functions
ora:contains (Oracle), 5-11, 12-17
ora:matches (Oracle), 5-12
ora:replace (Oracle), 5-12
ora:sqrt (Oracle), 5-13
ora:tokenize (Oracle), 5-13
item
definition, 5-2
namespaces, 5-9, 5-27
optimization, 5-29
optimization over relational data, 5-31
Oracle extension functions, 5-11
Oracle XML DB support, 5-42
performance, 5-29
predefined namespaces and prefixes, 5-9
referential transparency
definition, 5-2
sequence
definition, 5-2
SQL*Plus XQUERY command, 5-38
tuning, 5-29
type-checking, static and dynamic, 5-37
unordered mode
definition, 5-2
use with Oracle XML DB Repository, 5-16
use with XMLType relational data, 5-23
optimization, 5-32
XMLQuery and XMLTable SQL functions, 5-5
examples, 5-15
XSD
definition, 1-13
xsi:noNamespaceSchemaLocation attribute, 7-4, 19-8
XSL style sheet

Index-13

definition, 13-20
XSLT
style sheets
for updating XML instance documents,
use with DBUri servlet, 3-88
use with Oracle XML DB, 3-64
use with package DBMS_
XSLPROCESSOR, 13-22

Index-14

10-10



File Type                       : PDF
File Type Extension             : pdf
MIME Type                       : application/pdf
PDF Version                     : 1.6
Linearized                      : Yes
Language                        : en
XMP Toolkit                     : Adobe XMP Core 5.2-c001 63.139439, 2010/10/03-12:08:50
Format                          : application/pdf
Title                           : Oracle XML DB Developer’s Guide
Creator                         : Oracle Corporation
Description                     : Oracle XML DB
Create Date                     : 2014:02:20 09:56:33Z
Creator Tool                    : FrameMaker 10.0.2
Modify Date                     : 2014:02:20 10:27:30-07:00
Metadata Date                   : 2014:02:20 10:27:30-07:00
Marked                          : True
Producer                        : Acrobat Elements 9.0.0 (Windows)
Document ID                     : uuid:54b950e6-e820-41ff-831a-459b71daba1f
Instance ID                     : uuid:5f3f7693-b2fb-4a69-8b77-da9019136255
Page Mode                       : UseOutlines
Page Count                      : 956
Author                          : Oracle Corporation
Keywords                        : XML, XQuery, XPath
Subject                         : Oracle XML DB