How to limit and sort the result set

[[EMAIL PROTECTED]]

Is it possible to specify a limit to the # results returned by an XPath 
query?
I have a DB with about 500 smallish documents in it, and applying an 
XPath expression to some frequently occuring attributes
keeps giving me an out of memory exception at the point :
       ResourceSet resultSet = service.query(xpathString);

A second question, is it possible to have these results sorted by a 
given attribute found in the ResultSet, or do I need to apply a
seperate XSLT to the result set to do this.

Many thanks for any assistance.
WH