Re: Typmod associated with multi-row VALUES constructs

Tom Lane wrote:
> Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> writes:
> > Tom Lane wrote:
> >> In HEAD, we could change the RTE data structure so that
> >> transformValuesClause could save the typmod information in the RTE,
> >> keeping the lookups cheap.
>
> > Hmm, I think this would be useful for the XMLTABLE patch too. I talked
> > a bit about it at
> > https://www.postgresql.org/message-id/20161122204730.dgipy6gxi25j4e6a@alvherre.pgsql
>
> I dunno. If your example there is correct that XMLTABLE can be called as
> a plain function in a SELECT list, then I doubt that we want to tie
> anything about it to the RTE data structure. If anything, the case where
> it appears in FROM seems to need to be treated as a generic RTE_FUNCTION
> case.

Well, XMLTABLE is specified by the standard to be part of <table primary>,
which it turn is part of <table reference>. I can't immediately tell
whether it allows XMLTABLE to be called like a regular function. The
current patch allows it, but maybe that's not right, and it's probably
not that useful anyway.

> I've been trying to avoid getting involved in the XMLTABLE patch, mainly
> because I know zip about XML, but maybe I need to take a look.

I think it'd be productive that you did so. The XML part of it is
reasonably well isolated, so you could give your opinion on the core
parser / executor parts without looking at the XML part.

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