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).

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.

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.

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).

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".

• 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.

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.

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.

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.

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.

• Oracle SQL function extract – Use SQL/XML function XMLQuery instead. See "XMLQUERY SQL/XML Function in Oracle XML DB".

• Oracle SQL function extractValue – Use SQL/XML function XMLTable or SQL/XML functions XMLCast and XMLQuery instead.

  • See "SQL/XML Functions XMLQUERY and XMLTABLE" for information about using function XMLTable

  • See "XMLCAST SQL/XML Function" for information about using functions XMLCast and XMLQuery

• Oracle SQL function existsNode – Use SQL/XML function XMLExists instead. See "XMLEXISTS SQL/XML Function".

• Oracle SQL function XMLSequence – Use SQL/XML function XMLTable instead. See "XMLTABLE SQL/XML Function in Oracle XML DB".

• 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".

• 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".

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".

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".

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.

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.

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".

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".

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".

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".

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".

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"

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".

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" for information about handling large nodes in PL/SQL and "Handling Large Nodes using Java".

Unified Java API

The Java XML APIs in Oracle XML DB and Oracle XML Developer's Kit have been unified.

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.

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".

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.

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" and "Generating XML using SQL Functions".

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.