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Re: xpath // query
- From: Peter Davis <pdavis152 at attbi dot com>
- To: xsl-list at lists dot mulberrytech dot com
- Date: Wed, 24 Apr 2002 05:51:09 -0700
- Subject: Re: [xsl] xpath // query
- References: <000501c1eb8b$4fa3f050$b10b0a0a@nki0413>
- Reply-to: xsl-list at lists dot mulberrytech dot com
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On Wednesday 24 April 2002 05:26, Aleksander Dye wrote:
> select="A//C"
> select="A//B//C"
>
> when I know that <B> is *guranteed* to be there (both select the same
> nodes). By adding the test for <B>, will it make the selection any faster?
Now, take whatever I say with a grain of salt because I haven't actually
implemented a processor or tested this. But it seems like the first might
actually be faster, because when using the second expression, each node under
<B> would probably be tested to see if it is a <B> *or* a <C>, while in the
first expression only the test for <C> must be made. This may or may not be
the case, depending on how smart/dumb your processor is.
On the other hand, if you were able to limit the '//' such as A/*/*/B//C, then
it would certainly be faster, but it sounds like this is not possible.
Remember that the only way to really find out for your given processor (and I
am sure it varies between processors) is to profile the actual runtimes.
- --
Peter Davis
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