Re: [HACKERS] Re: [HACKERS] XQuery or XPathサポート

On 3/5/07, Tatsuo Ishii <ishii@postgresql.org> wrote:
> From: "Nikolay Samokhvalov" <samokhvalov@gmail.com>
> > I've submitted patch for simple XPath 1.0 support (based on libxml2):
> > http://archives.postgresql.org/pgsql-patches/2007-03/msg00088.php
>
> But contrib/README.xml2 stated:
>
> "This version of the XML functions provides both XPath querying and
> XSLT functionality"
>
> What's the difference between yours and contrib/xml2?

"Mine" is supposed to go to the core. And, contrib/xml2 contains less
"semantically clear" functions, that were developed for practical
purposes (e.g. xml_number() returns only one, first number from the
suquence).

>
> > This function does XML parsing at query time. So, you should use
> > functional indexes over this function to reach good perfromance.
> >
> > My curent plans include development of additional contrib module for
> > alternative (experimental), efficient support of XPath (no XML parsing
> > at query time), similar to Microsoft's ORDPATHs. This project is
> > called "xlabel" and I hope to implement its prototype soon.
>
> Also Peter seems to add xml datatype to 8.3. Does your functuion
> handle this data type?

Of course. Peter's patches are partially based on the result of my
SoC2006 work ("Initial XML support for PostgreSQL"). XPath patch was
discussed with him and in -hackers, now I'm waiting for its review.

--
Best regards,
Nikolay