Re: patch: function xmltable

Pavel Stehule wrote:
> Hi
> 
> I used your idea about special columns when COLUMNS are not explicitly
> defined.
> 
> All lines that you are dislike removed.

I just pushed XMLTABLE, after some additional changes.  Please test it
thoroughly and report any problems.

I didn't add the change you proposed here to keep COLUMNS optional;
instead, I just made COLUMNS mandatory.  I think what you propose here
is not entirely out of the question, but you left out ruleutils.c
support for it, so I decided to leave it aside for now so that I could
get this patch out of my plate once and for all.  If you really want
that feature, you can submit another patch for it and discuss with the
RMT whether it belongs in PG10 or not.

Some changes I made:
* I added some pg_stat_statements support.  It works fine for simple
tests, but deeper testing of it would be appreciated.

* I removed the "buildercxt" memory context.  It seemed mostly
pointless, and I was disturbed by the MemoryContextResetOnly().
Per-value memory still uses the per-value memory context, but the rest
of the stuff is in the per-query context, which should be pretty much
the same.

* Desultory stylistic changes

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
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