RE: [xsl] External XML Document Caching

Subject: RE: [xsl] External XML Document Caching
From: "Michael Kay" <mike@xxxxxxxxxxxx>
Date: Fri, 21 Nov 2008 20:24:49 -0000
> The external file is accessed via the document('...') function.
> My question number 1: Do XSLT processors cache external 
> referenced XML files?

Probably not, but obviously it depends on the processor. However, most
processors allow you to preload the document from the calling API. You may
find it better to supply the lookup document as the value of a stylesheet
parameter; if you do it using the document() function you can implement a
URIResolver or equivalent that maintains the cache.
> Question number 2: Do you recommend any strategies to 
> optimise the query to the external XML file? I have 
> considered the following, but I am unsure as how each of them 
> can improve performance:
>    - Using the xsl:key + key function on the external 
> document('...') file.
>    - Implement the lookup table in a XSL file, specifying the 
> mappings outside the <xsl:templates> so that they are not 
> rendered. 

Using keys will generally improve performance significantly, unless you are
using a processor like Saxon-SA that does the optimization automatically. I
can't see how your other idea would help.

Michael Kay

Current Thread