Designing XML Schemas for use in Oracle 10 - flatter is better or nested is better?

Hi Folks,

 

Suppose that you are designing an XML Schema for use in an Oracle 10
database.  

 

Does the fact that the Schema is being used in Oracle 10 influence how
you design the Schema?  

 

A colleague told me that, in Oracle 10, queries on data that is
structured in a flat fashion are faster than queries on data that is
structured in a nested (hierarchical) fashion.  "Therefore, we must
design our XML Schemas to structure the data in a flat fashion."  

 

Is my colleague correct - in Oracle 10 queries are faster on flat data
than nested data?

 

I hate to be forced into making Schema design decisions based on the
limitations of the tool being used.  However, we are using Oracle 10,
and if performance is poor on data that is hierarchical then I must be
practical and structure the data in a flat fashion. 

 

Does anyone have experience with designing XML Schemas for use in
Oracle 10?  What's your recommendation - flat or nested?   /Roger