From: Guillaume Smet <guillaume.smet@openwide.fr>
To: Andrew Sullivan <ajs@crankycanuck.ca>
Cc: pgsql-performance@postgresql.org
Subject: Re: weird performances problem
Date: Tue, 22 Nov 2005 10:49:22 +0100
Message-ID: <4382E9A2.5080102@openwide.fr> (raw)
In-Reply-To: <20051118161312.GC28967@phlogiston.dyndns.org>
References: <437CC21D.8070402@openwide.fr>
<20051117221314.GC26696@phlogiston.dyndns.org>
<437D13AA.4010309@openwide.fr>
<20051118161312.GC28967@phlogiston.dyndns.org>
Andrew,
> I would be very suspicious of that much memory for sort. Please see
> the docs for what that does. That is the amount that _each sort_ can
> allocate before spilling to disk.
> If some set of your users are
> causing complicated queries with, say, four sorts apiece, then each
> user is potentially allocating 4x that much memory. That's going to
> wreak havoc on your disk buffers (which are tricky to monitor on most
> systems, and impossible on some).
Yes, we have effectively complicated queries. That's why we put the
sort_mem so high. I'll see if we can put it lower for the next few days
to see if it improves our performances.
Thanks for your help.
--
Guillaume
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To: pgsql-performance@postgresql.org
Cc: guillaume.smet@openwide.fr, ajs@crankycanuck.ca
Subject: Re: weird performances problem
In-Reply-To: <4382E9A2.5080102@openwide.fr>
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