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Re: XPath perfomance in attributes or nodes?
I would like to ask the XSLT implementors on this list whether their
processors build keys lazily (i.e. on the first use of the key() function),
or does <xsl:key> have a cost even when the key is not used later ?
When is the cost of building the index offset by the performance gain ?
For example, suppose the input is 10000 elements like so :
<doc>
<elt att="1">
</elt>
<elt att="2">
</elt>
<elt att="3">
</elt>
...
</doc>
and there is an external parameter that gives the stylesheet
an attribute value to look for. Which would be faster :
<xsl:key name="idx" match="elt" use="@att" />
<xsl:param name="param" />
<xsl:template ...>
...
<xsl:apply-templates select="key('idx',$param)" />
...
</xsl:template>
Or :
<xsl:param name="param" />
<xsl:template ...>
...
<xsl:apply-templates select="/doc/elt[@att=$param]" />
...
</xsl:template>
Assuming the <xsl:apply-templates> above is executed
only once, it seems to me that the key-less version
should perform a bit faster. But as I have never implemented
an XSLT processor I would like to have the opinion of
masters of the subject.
Cheers,
--Jonathan
----- Original Message -----
From: "Peter Davis" <pdavis152@attbi.com>
To: <xsl-list@lists.mulberrytech.com>
Sent: Thursday, March 07, 2002 3:52 AM
Subject: Re: [xsl] XPath perfomance in attributes or nodes?
> <xsl:key name="project-uid" match="project" use="@uid"/>
> <!-- or use="uid" -->
> <xsl:template ...>
> <xsl:apply-templates select="key('project-uid',
> '{6A97F258-93A7-4C5E-B712-052130A5208C}')[1]"/>
> <!-- [1] is probably not necessary -->
> </xsl:template>
>
> will be much faster than either approach.
>
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