Oracle9i database has a new native XMLType for storing XML content. This new type is in the same tradition as other new types that have appeared in the Oracle server over 8.0 and 8i.

XMLType gives developers a convenient abstraction to store XML content. There are a number of built-in member functions on this type that enable developers to manipulate XML content.

Today, the data stored in an XMLType is stored as a character LOB (CLOB). In the future, we will also support other forms of storage - exploded object-relational, name-value pairs etc. Whatever the storage, the developer will only deal with an XMLType. Hence this is an "abstraction" over different storage models for XML.

Oracle9i Database Native XML Support and XML Developer's Kits

Benefits of XMLType

Using XMLType has the following advantages:

• It brings the worlds of XML and SQL together as it enables:
  • SQL operations on XML content
  • XML operations on SQL content
• It is convenient to implement as it includes built-in member functions, indexing support, navigation, and so on.
• XMLType uses the built-in XML parser and processor to provide better performance and scalability

Specifically, XMLType can be combined with other columns and datatypes in SQL statements. For example, you can query XMLType columns, join the result of the extraction with a relational column, and then Oracle can determine an optimal way to execute these queries.

XMLType is also optimized to not materialize the XML data into a tree structure unless needed. Hence when SQL selects XMLType instances inside queries, only a serialized form is exchanged across function boundaries. These are exploded into tree format only when operations such as extract() and existsNode() are performed. The internal structure of XMLType is also an optimized DOM-like tree structure.

Finally, you can create functional indexes on Existsnode and Extract functions to dramatically speed up query evaluation. Oracle9i text index has also been enhanced to support XMLType columns.

	Visit the Oracle XML Technology page for more information
	Oracle 9i Application Developer's Guide - XML Release 1: Chapter 5 - Database Support for XML

Archives