Re: XML in PostgreSQL

On Thu, 27 Feb 2003 05:28:58 +0000, Joel Rodrigues wrote:

> Hi,
>
> Surprisingly there doesn't seem to be much discussion about the issue of
> storing and working with XML in PostgreSQL. Or maybe this is the wrong
> list to look for that ?
>
> The README in Contrib/XML in PostgreSQL 7.2.2 by John Gray is dated 16
> August 2001, and the identically dated TODO file lists some very
> important things. Has there been any update of this or related work for
> PostgreSQL ?
>
This list is probably as good as any! I did some client-specific
development work on contrib/xml last September - which also had the effect
of verifying that it was faster than I expected (and libxml2 supports
quite a rich part of the XPath syntax, so it's quite a handy thing).

In terms of the TODO items, my feeling is: 1) Persistent storage:
complicated and unnecessary for only a small benefit. 2) XQuery: don't
know 3) DOM interfaces: Runs into the persistent storage problem.
On-the-fly parsing seems OK for document fragments. 4)Returning sets of
documents: the new set-returning functions make this sort of thing much
more straightforward. Indexing - still an interesting possibility I think
but haven't really thought further about it. [There is someone who has
contacted me because he's adding a Set-returning function to contrib/xml.
To my shame I haven't replied to one of his questions yet. 5) Return types
- this is a straightforward case of writing wrapper/conversion functions.
This was one of the things I did for my client in September.

> My interest is in working with 'document-centric' XML. Would using an
> external XML module, such as Python's PyXML allow for sufficiently quick
> performance, or at least performance that would be comparable to that of
> using a native PostgreSQL module ?
>

This was my environment too (I'm now in full-time employment as a
broadcast engineer who doesn't have much work opportunity to use Pg
however) and I'd have liked to have done more work with the module. There
are people using it and it seems to work OK.

What sort of things do you want to do?

Regards

John