Oracle XML DB is a feature of the Oracle Database. It provides a high-performance, native XML storage and retrieval technology. It fully absorbs the W3C XML data model into the Oracle Database, and provides new standard access methods for navigating and querying XML. With Oracle XML DB, you get all the advantages of relational database technology plus the advantages of XML.
In Oracle Database 11g Release 2, new capabilities, such as XMLIndex structured component and partitioning, as well as numerous enhancements of Oracle XML DBare introduced to dramatically improve its performance, scalability, XML schema management, and XML information lifecycle management.
The XML DB Sample Code Library contains downloadable code samples to help you understand how to develop applications that take advantage of Oracle's XML technology and the Oracle XML DB Repository. Installation instructions for the code samples can be found here