Andrew Dunstan wrote:
Matthias Brantner wrote:
I know this has been discussed several times and it seems the
conclusin was it's impossible if we would like to use existing XQuery
external modules (some are by license reasons and some are by
techinical reasons).
So it seems the only way to support XQuery is, developing our own
XQuery functionality from scratch. I'm wondering if other people reach
the same conclusion as me, or is it a totaly impossible project?
Well xquilla on top of xerces should get us pretty much were we need
to go. They are both under the Apache 2 license, which I believe
would be ok. But they are C++ so I don't know if we could use them.
I found Zorba, its C++ and Apache 2. But I don't know much about it.
But it looks promising.
http://www.zorba-xquery.com/
Sounds like a great project. Please, let us know
(zorba-us...@lists.sourceforge.net) if you need any help or have
questions with regard to plugging Zorba to PostGreSQL. We would love
to see this happen and help.
Well, maybe you can answer the questions I had last time I looked at it,
namely:
XQuery is a whole other question. Adding another library dependency is
something we try to avoid. Zorba <http://www.zorba-xquery.com/> might
work, but it appears to have its own impressive list of dependencies
(why does it require both libxml2 and xerces-c? That looks a bit
redundant.)
Even if we did implement XMLTABLE, I think I'd probably be inclined to
start by limiting it to plain XPath, without the FLWOR stuff. I think
that would satisfy the vast majority of needs, although you might feel
differently. (Do a Google for XMLTABLE - every example I found uses
plain XPath expressions.)
A much more urgent need we have, IMNSHO, than for XQuery, is for XSLT
support that actually works. But maybe that's just me.
I've been playing around with Zorba and xQilla today. I couldn't
actually get Zorba to build on my system. It looks like the two share a
common (or similar) C API though. Zorba also had perl, Python, Ruby and
PHP bindings (which I also couldn't get to work) but would be nice to be
able to use from plperl, plpython, plruby also.
If it were possible to drop the xerces dependency from Zorba and use
libxml2 for parsing, that would be a strong case for it. The other big
dependency for Zorba was ICU for converting character sets. I'm not
familiar with that part of Postgres. But it seems to me that we would
have our own libraries for that sort of thing.
I'm not a big fan of doing XSLT in the database. But xQilla would give
you XSLT 2.0 support.
Scott
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
