----- Original Message -----
Sent: Wednesday, December 19, 2001 6:39
PM
Subject: XPath Performance
Hi,
I am having some performance problems with XPath I
was
hoping you could help with.
I am writing an app that parses an xsd file by
first doing a
selectNodeList on all the
<complexTypes> elements then a
selectNodeList on all the <sequence/element> elements using
complexType
as the parent.
When I went from parsing a small xsd to a larger
one (about 140 complexType) nodes
I noticed
significant performance problems with load times over 2 minutes.
I started checking and found the selectNodeList on
the <elements> elements
was starting
out well but then ended up being very slow by time I got
to the end (bottom) nodes (top nodes: ~50ms. Bottom
nodes ~700 ms).
It seems the xpath is searching from the start of
the document everytime
when that is not
necessary. The exact call is selectNodeList(elemComplexType,
"sequence/element"). When I removed this and
made my own norrow routine for this
search,
the time went down to 0ms and the load for the entire file dropped to
about 2 secs. Am I doing anything wrong or
is XPath searching from the start
of the
document. I need to resolve this, since my app uses XPath
extensively.
Thank you,
Eric
Walsh
