Re: [xsl] Very slow Xsl (just started in xsl)

[David Carlisle <davidc@xxxxxxxxx>]

It's hard to debug without a full stylesheet and full (small) input but
in general beware using // which means do a full search of the document
to arbitrary depth. If you are lucky your xslt processor may rewrite
your expressions not to do this, but things are simpler if you don't use
// in the first place.

for example
	     <xsl:for-each select="//data/*">

means search the entire document for data elements.
If you know your data elements are at a certain fixed level then it's
likely to be better to do eg
	     <xsl:for-each select="/a/b/data/*">

		           <xsl:for-each select="//layout/field">
 then _for each child of a data element_ search the entire document
 again looking for layout elements. the set of layout/field elements
 returned will be the same every time, so if you are lucky the processor
 will only do this once, but it would be better to pull this out into a
 global variable, and also again if you know a more specific path to the
 layout element, use it.


<xsl:variable name="poscol">
                 <xsl:for-each select="//layout/field">
                     <xsl:if test="vldidx = $col">
                          <xsl:value-of select="position()"/>
                     </xsl:if>

again this looks very slow, it appears to be looking up a field by its
vldidx child in which case use of  xsl:key would problably speed things
up, but I lost the logic of how you are using postion() here (just
looking at the code without any example) so I won't suggest a
replacement.

David

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