Re: idea: global temp tables

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
Cc: "Alvaro Herrera" <alvherre(at)commandprompt(dot)com>, "Pavel Stehule" <pavel(dot)stehule(at)gmail(dot)com>, "PostgreSQL Hackers" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: idea: global temp tables
Date: 2009-04-28 16:38:25
Message-ID: 5422.1240936705@sss.pgh.pa.us
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"Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> writes:
> Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> it could be considered either a global or a local temp table per
>> spec (without any module support you can't really say which it is).

> That seems bogus -- without modules it is clearly not LOCAL.

You could just as easily say it's not GLOBAL.

> What
> Pavel is requesting exactly matches the spec's definition of a global
> temporary table, but it does make me uneasy that after accepting the
> standard syntax, and behaving differently from it (including making no
> distinction between GLOBAL and LOCAL declarations) we would suddenly
> go to compliance on GLOBAL declarations but leave LOCAL as is.

Right. What I'm suggesting is that before we mess with this we should
have a road map on whether we are going to try to get to spec
compliance in this area, and if so how.

One thing I just noticed is that the spec does not consider GLOBAL/LOCAL
to be optional --- per spec you *must* write one or the other in front
of TEMPORARY. So we could adopt the view that omitting this keyword
implies our current non-spec behavior (which is far too useful to give
up, spec compliance or no) while writing one or the other selects the
spec behavior. However, if we're going to do that then we should start
throwing warnings for use of the keywords, preferably before the release
in which they actually start doing something different.

regards, tom lane

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