From: Andrew Sullivan <ajs@crankycanuck.ca>
To: Guillaume Smet <guillaume.smet@openwide.fr>
Cc: Andrew Sullivan <ajs@crankycanuck.ca>
Cc: pgsql-performance@postgresql.org
Subject: Re: weird performances problem
Date: Fri, 18 Nov 2005 11:13:12 -0500
Message-ID: <20051118161312.GC28967@phlogiston.dyndns.org> (raw)
In-Reply-To: <437D13AA.4010309@openwide.fr>
References: <437CC21D.8070402@openwide.fr>
<20051117221314.GC26696@phlogiston.dyndns.org>
<437D13AA.4010309@openwide.fr>
On Fri, Nov 18, 2005 at 12:35:06AM +0100, Guillaume Smet wrote:
> sort_mem = 32768
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).
This'd be the first knob I'd twiddle, for sure.
A
--
Andrew Sullivan | ajs@crankycanuck.ca
It is above all style through which power defers to reason.
--J. Robert Oppenheimer
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: ajs@crankycanuck.ca, guillaume.smet@openwide.fr
Subject: Re: weird performances problem
In-Reply-To: <20051118161312.GC28967@phlogiston.dyndns.org>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox