Thanks Liam We are building a platform to which codes containing xpaths are submitted by external users. Manual optimization of xpaths are infeasible. Do you know about any tools that can automate it?
- Z On Oct 18, 2012, at 7:15 PM, Liam R E Quin <[email protected]> wrote: > On Thu, 2012-10-18 at 18:00 -0700, Zhigang Chen wrote: >> Hi >> >> We sometimes run into the situation where a pretty expensive xpath >> (e.g. .//table//td[@class]) is run on a big document (~ 9M) and it >> takes very very long. In fact we never see it finish. > > [resending from the right account, sorry] > > I routinely do queries like that with a 50 MByte document, but with > XQuery implementations (XPath 2) rather than XPath 1. I get results in > the order of a few milliseconds. > > It would probably be worth adding element indexes to libxml2, even if > they can't easily be built during parsing. > > In the meantime you could try to speed this query up yourself by writing > it as > .//tr[@class] > or, if this is not HTML., > .//tr[@class][ancestor::table] > > Liam > > -- > Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/ > Pictures from old books: http://fromoldbooks.org/ > Ankh: irc.sorcery.net irc.gnome.org freenode/#xml > Co-author, 5th edition of "Beginning XML", Wrox, July 2012 > -- > Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/ > Pictures from old books: http://fromoldbooks.org/ > Ankh: irc.sorcery.net irc.gnome.org freenode/#xml > _______________________________________________ xml mailing list, project page http://xmlsoft.org/ [email protected] https://mail.gnome.org/mailman/listinfo/xml
