From: Tom Lane <tgl@sss.pgh.pa.us>
To: Nikolas Everett <nik9000@gmail.com>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: explain analyze reports that my queries are fast but they run very slowly
Date: Thu, 27 Dec 2012 18:12:31 -0500
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Nikolas Everett <nik9000@gmail.com> writes:
> On Thu, Dec 27, 2012 at 4:33 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Nikolas Everett <nik9000@gmail.com> writes:
>>> We straced the backend during the explain and it looked like the open
>>> commands were taking several seconds each.
>> Kind of makes me wonder if you have a whole lot of tables ("whole lot"
>> in this context probably means tens of thousands) and are storing the
>> database on a filesystem that doesn't scale well to lots of files in one
>> directory. If that's the explanation, the reason the 8.3 installation
>> was okay was likely that it was stored on a more modern filesystem.
> We have 1897 files for our largest database which really isn't a whole lot.
OK...
> The old servers were EXT3 over FC to a NetApp running RHEL5 PPC. The new
> servers are on NFS to the same NetApp running RHEL5 Intel.
Now I'm wondering about network glitches or NFS configuration problems.
This is a bit outside my expertise unfortunately, but it seems clear
that your performance issue is somewhere in that area.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, nik9000@gmail.com
Subject: Re: explain analyze reports that my queries are fast but they run very slowly
In-Reply-To: <21869.1356649951@sss.pgh.pa.us>
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