Re: DELETE syntax on JOINS

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
Cc: Bruce Momjian <bruce(at)momjian(dot)us>, Jean-Michel Pouré <jm(at)poure(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: DELETE syntax on JOINS
Date: 2009-08-24 16:50:24
Message-ID: 14512.1251132624@sss.pgh.pa.us
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Alvaro Herrera <alvherre(at)commandprompt(dot)com> writes:
> Bruce Momjian wrote:
>> So the problem is that our DELETE ... USING does not allow ANSI join
>> syntax? Can that be added?

> Not sure about that. USING is already an extension to the standard, so
> if we extend it a bit more, it can't be a problem, can it?

I don't see any very good way to extend the USING syntax to allow the
target table to be outer-joined to something else. Some other systems
allow it by letting you re-specify the target in the other clause,
equivalently to

DELETE FROM target t USING t LEFT JOIN other_table ot ON ...

but we have always considered that the target is *not* to be identified
with any member of the FROM/USING clause, so it would be a serious
compatibility break to change that now.

regards, tom lane

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