Re: [xsl] measuring performance of XSLT stylesheet

["G. Ken Holman" <gkholman@xxxxxxxxxxxxxxxxxxxx>]

At 2009-11-22 13:03 -0600, a kusa wrote:
> Thanks for your input. What little I know about using "//" is that the
> processor checks a whole document when a "//element" is used. If we
> are talking about a really big document (few mB) this would definitely
> slow down the transformation processing time.
>
> Right?

In general, yes ... for example, looking for a section title way down 
deep under figure captions is a waste of time.

Note, however, that some processors can actually optimize "//" into 
keyed lookup tables that vastly improve performance.  Since they can 
analyze the stylesheet to see what kinds of nodes are being looked 
for, a lookup table can be built with knowledge of where the nodes are.

But I tell my students not to rely on that and that any time they 
think they need "//" to think again because they probably don't 
unless they indeed want to check every leaf of every subtree of the 
entire document looking for something.

I hope this helps.

. . . . . . . . . . Ken


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