Re: [Fwd: [Bratislava-pm] XML::LibXML performance]

On st 10. září 2008, Emmanuel Rodriguez wrote:
> Petr Pajas wrote:
> > Hi,
> >
> > Tim is right. This is also the reason why SAX2 parsing is slow
> > in Perl. As for XPath performance, provided that you do not
> > modify the document significantly during your processing, you
> > may try calling
> >
> > $doc->indexElement;
>
> I tried this one first, but it was done in the second version of
> the script, that one that had all XPath striped. With that script
> there was no improvement since XPath was used only once.
>
> > before you start XPath queries on your document.
> >
> > Another potential for improving XPath performance seemed to me
> > to be in letting the user pre-compile static XPath expressions
> > and reuse them in the pre-compiled form. The API, soon to
> > appear in the SVN, looks like:
> >
> > my $comp_xpath = XML::LibXML::XPathExpression->new($xpath);
>
> This is great and will be highly appreciated. I hope that the the
> pre-compilation of XPath expressions will allows us to interact
> with XML::LibXML::XPathContext or provide some other way to
> define the namespaces to used in the query.

Yes, you will be able to pass the resulting object to any find... 
method of X::L::Node or X::L::XPathContext where you would normally 
pass XPath expression as a string.

Pre-compiling does not resolve namespace prefixes, so you need to 
register them with an XPathContext, as usual.

I have committed the code and documentation a minute ago, so you can 
check out from the SVN and try. Instructions for compiling from SVN 
are in the README file:

http://search.cpan.org/src/PAJAS/XML-LibXML-1.66/README

-- Petr
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