From: Joshua D. Drake <jd@commandprompt.com>
To: Patrick Donlin <pdonlin@oaisd.org>
Cc: pgsql-performance@postgresql.org
Subject: Re: Identical query slower on 8.4 vs 8.3
Date: Thu, 15 Jul 2010 10:17:21 -0700
Message-ID: <1279214241.30528.42.camel@jd-desktop.unknown.charter.com> (raw)
In-Reply-To: <1187615879.13268921279204882941.JavaMail.root@mm-mailstore02.merit.edu>
References: <1187615879.13268921279204882941.JavaMail.root@mm-mailstore02.merit.edu>
On Thu, 2010-07-15 at 10:41 -0400, Patrick Donlin wrote:
> Results when running on the v8.3.7 server....
> Total query runtime: 32185 ms.
> 700536 rows retrieved.
>
> Results when running on the v8.4.4 server....
> Total query runtime: 164227 ms.
> 700536 rows retrieved.
>
>
> Anyone have any ideas on where I should start looking to figure this
> out? I didn't perform any special steps when moving to v8.4, I just
> did a pg_dump from the 8.3 server and restored it on the new 8.4
> servers. Maybe that is where I made a mistake.
Three immediate things come to mind:
1. One had relations in file or shared buffer cache, the other didn't
2. One is running ext4 versus ext3 and when you end up spilling to disk
when you over run work_mem, the ext4 machine is faster, but without
knowing which machine is which it is a bit tough to diagnose.
3. You didn't run ANALYZE on one of the machines
Sincerely,
Joshua D. Drake
>
> Thanks!
> Patrick
>
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To: pgsql-performance@postgresql.org
Cc: jd@commandprompt.com, pdonlin@oaisd.org
Subject: Re: Identical query slower on 8.4 vs 8.3
In-Reply-To: <1279214241.30528.42.camel@jd-desktop.unknown.charter.com>
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