Re: PL/pgSQL PERFORM with CTE

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Josh Berkus <josh(at)agliodbs(dot)com>
Cc: Jan Wieck <JanWieck(at)Yahoo(dot)com>, Merlin Moncure <mmoncure(at)gmail(dot)com>, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, "David E(dot) Wheeler" <david(at)justatheory(dot)com>, pgsql-hackers Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: PL/pgSQL PERFORM with CTE
Date: 2013-08-22 23:35:32
Message-ID: 27815.1377214532@sss.pgh.pa.us
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Josh Berkus <josh(at)agliodbs(dot)com> writes:
> I have to agree with Merlin. I've always thought the PERFORM thing was
> a wart we'd get around to removing eventually. In what way is it a feature?

I'd always assumed it was a PL/SQL compatibility thing, but a look in a
PL/SQL reference doesn't turn up any such statement. So far as I can see,
the situation in Oracle PL/SQL is:
* SELECT must have an INTO clause;
* there isn't any way to execute a SELECT and just discard the result.

Jan might remember more about his thought process here, but I'm thinking
that he copied the SELECT-must-have-INTO rule and then chose to invent
a new statement for the case of wanting to discard the result. I think
you could make an argument for that being good from an oversight-detection
standpoint, but it's not a really strong argument. Particularly in view
of the difficulty we'd have in supporting WITH ... PERFORM ... nicely,
it doesn't seem unreasonable to just allow SELECT-without-INTO.

regards, tom lane

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