Re: 8.3rc1 Out of memory when performing update

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Stephen Denne" <Stephen(dot)Denne(at)datamail(dot)co(dot)nz>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: 8.3rc1 Out of memory when performing update
Date: 2008-01-25 04:50:25
Message-ID: 22975.1201236625@sss.pgh.pa.us
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"Stephen Denne" <Stephen(dot)Denne(at)datamail(dot)co(dot)nz> writes:
> I altered the update statement slightly, and reran the query.
> The altered query has been running over 3 hours now,
> without using lots of memory (38M private bytes).
> 2046 temp files were created (2.54GB worth),
> which have recently changed from slowly growing in size
> to very very slowly reducing in number.

Hmm. I think what that really means is you haven't got to the part of
the query where the leak is :-(. In my attempt to reproduce this
I found that 8.3 has introduced a memory leak into the RI trigger
support, such that even if an UPDATE doesn't change the FK columns
it's still likely to leak a few dozen bytes per updated row.

Please see if the attached patch makes it better for you.

regards, tom lane

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