Its time to get rid of some backlog about Oracle 11gR2 XML DB features. Ones of them is about the new Structured XMLIndex or also called XMLIndex Structured Component. So in Oracle 11gR2 you have the ability to use a “unstructured” XMLIndex (UXI) and a “structured” XMLIndex (SXI). The use cases for these global index types specially designed for the XML DB realm are described in the Oracle XMLDB Developers Guide for 11gR2 and in short are show in the following picture.
Also see my SlideShare presenation called “Oracle Database 11g Release 2 – XMLDB New Features” for Oracle Open World 2009.
Some general info/rules about 11gR2 XMLIndex use (in no specific order):