From: Tom Lane <tgl@sss.pgh.pa.us>
To: Arnaud Lesauvage <thewild@freesurf.fr>
Cc: Ragnar <gnari@hive.is>
Cc: Jens Schipkowski <jens.schipkowski@apus.co.at>
Cc: pgsql-performance@postgresql.org
Subject: Re: Slow update with simple query
Date: Thu, 14 Dec 2006 11:19:00 -0500
Message-ID: <21233.1166113140@sss.pgh.pa.us> (raw)
In-Reply-To: <45816C54.5010602@freesurf.fr>
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Arnaud Lesauvage <thewild@freesurf.fr> writes:
> Tom Lane a écrit :
>> It seems the time must be going into this trigger function. What
>> does it do?
> A lot of things ! Indeed, if it runs it will very badly hurt performances (table
> lookups, string manipulation, etc...) !
> But it should only be tringered on INSERTs, and I am doing an UPDATE !
Doh, right, I obviously still need to ingest more caffeine this morning.
I think the conclusion must be that there was just too much I/O to be
done to update all the rows. Have you done any tuning of shared_buffers
and so forth? I recall having seen cases where update performance went
bad as soon as the upper levels of a large index no longer fit into
shared_buffers ...
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, thewild@freesurf.fr, gnari@hive.is, jens.schipkowski@apus.co.at
Subject: Re: Slow update with simple query
In-Reply-To: <21233.1166113140@sss.pgh.pa.us>
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