Re: patch: function xmltable

Pavel Stehule <pavel.stehule@gmail.com>

From: Pavel Stehule <pavel.stehule@gmail.com>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Craig Ringer <craig@2ndquadrant.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2017-01-17T18:07:42Z
Lists: pgsql-hackers
2017-01-16 23:51 GMT+01:00 Alvaro Herrera <alvherre@2ndquadrant.com>:

> Given
> https://www.postgresql.org/message-id/20170116210019.
> a3glfwspg5lnfrnm@alap3.anarazel.de
> which is going to heavily change how the executor works in this area, I
> am returning this patch to you again.  I would like a few rather minor
> changes:
>
> 1. to_xmlstr can be replaced with calls to xmlCharStrdup.
> 2. don't need xml_xmlnodetostr either -- just use xml_xmlnodetoxmltype
>    (which returns text*) and extract the cstring from the varlena.  It's
>    a bit more wasteful in terms of cycles, but I don't think we care.
>    If we do care, change the function so that it returns cstring, and
>    have the callers that want text wrap it in cstring_to_text.
> 3. have a new perValueCxt memcxt in TableExprState, child of buildercxt,
>    and switch to it just before GetValue() (reset it just before
>    switching).  Then, don't worry about leaks in GetValue.  This way,
>    the text* conversions et al don't matter.
>
> After that I think we're going to need to get this working on top of
> Andres' changes.  Which I'm afraid is going to be rather major surgery,
> but I haven't looked.
>

I'll try to clean xml part first, and then I can reflect the SRF changes. I
am not sure if I understand to all your proposed changes here, I have to
look there.

Regards

Pavel

>
> --
> Álvaro Herrera                https://www.2ndQuadrant.com/
> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
>

Commits

  1. Support XMLTABLE query expression

  2. Create <sect3> in the functions-xml section

  3. Improve handling of "UPDATE ... SET (column_list) = row_constructor".

  4. Add xmlexists function