Re: [HACKERS] Memory grows without bounds in aggregates!

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Michael Contzen <mcontzen(at)dohle(dot)com>
Cc: pgsql-hackers(at)postgreSQL(dot)org
Subject: Re: [HACKERS] Memory grows without bounds in aggregates!
Date: 1999-03-28 17:14:54
Message-ID: 24111.922641294@sss.pgh.pa.us
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Michael Contzen <mcontzen(at)dohle(dot)com> writes:
> [ out of memory for ]
> stamm=> select sum(ekumsatz), sum(vkumsatz),sum(lvkumsatz),count(*) from
> west0;

Right, this is an instance of a known problem (palloc'd temporaries for
aggregate functions aren't freed until end of statement). I think
someone was looking into a quick-hack patch for aggregates, but there
are comparable problems in evaluation of WHERE expressions, COPY, etc.
We really need a general-purpose solution, and that probably won't
happen till 6.6.

In the meantime, I expect that doing only one float8 sum() per select
would take a third as much memory --- you might find that that's an
adequate workaround for the short run.

regards, tom lane

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