From: Joe Conway <mail@joeconway.com>
To: Josh Berkus <josh@agliodbs.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: Hardware performance for large updates
Date: Thu, 05 Sep 2002 21:33:16 -0700
Message-ID: <3D78300C.7030403@joeconway.com> (raw)
References: <web-1635430@davinci.ethosmedia.com>
Josh Berkus wrote:
> The problem: The update series (done as a function) takes 10-15
> minutes. During this time, the CPU is never more than 31% busy, only
> 256mb of 512 is in use, and the disk channel is only 25% - 50%
> saturated. As such, is seems like we could run things faster.
>
> What does everybody suggest tweaking?
>
I think we'd need more information to be of any help -- schema,
functions, explain output, etc.
I do think you probably could increase Shared Buffers, as 256 is pretty
small. There's been a lot of debate over the best setting. The usual
guidance is start at 25% of physical RAM (16384 == 128MB if you have
512MB RAM), then tweak to optimize performance for your application and
hardware. You might also bump sort mem up a bit (maybe to 2048). Again,
I would test using my app and hardware to get the best value. Are you on
a Linux server -- if so I found that fdatasync works better than (the
default) fsync for wal_sync_method.
HTH,
Joe
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Subject: Re: Hardware performance for large updates
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