From: Joshua D. Drake <jd@commandprompt.com>
To: Miguel Arroz <arroz@guiamac.com>
Cc: Greg Smith <gsmith@gregsmith.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: UPDATE 66k rows too slow
Date: Mon, 10 Mar 2008 16:22:31 -0700
Message-ID: <20080310162231.6f54c5cd@commandprompt.com> (raw)
In-Reply-To: <A2F62126-69AA-4AE8-AB99-F5D94BAD1BD1@guiamac.com>
References: <879F65BD-D1B0-4D15-BAE3-056305B84474@guiamac.com>
<Pine.GSO.4.64.0803100040560.318@westnet.com>
<A2F62126-69AA-4AE8-AB99-F5D94BAD1BD1@guiamac.com>
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On Mon, 10 Mar 2008 23:17:54 +0000
Miguel Arroz <arroz@guiamac.com> wrote:
> Hi!
>
> I read and did many stuff you pointed me too. Raised shared
> buffers to 180 MB, and tried again. Same results.
>
> I deleted the DB, created a new one and generated new test data.
> I know have 72k rows, and the same query finishes in... 9 seconds.
>
> I'm totally clueless. Anyway, two questions:
>
> 1) My working_mem is 2 MB. Does an UPDATE query like main depend
> on working_mem?
>
> 2) I still feel this is all very trial-and-error. Change value,
> run query, hope it solves the problem. Well, the DB itself knows what
> is doing. Isn't there any way to make it tell us that? Like "the
> working mem is too low" or anything else. I know the problem is not
> the checkpoints, at least nothing appears on the log related to that.
> But it irritates me to be in front of a such complex system and not
> being able to know what's going on.
What does iostat -k 1 tell you during the 9 seconds the query is
running?
Joshua D. Drake
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Cc: jd@commandprompt.com, arroz@guiamac.com, gsmith@gregsmith.com
Subject: Re: UPDATE 66k rows too slow
In-Reply-To: <20080310162231.6f54c5cd@commandprompt.com>
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