From: Greg Smith <greg@2ndQuadrant.com>
To: pgsql-performance@postgresql.org
Subject: Re: wal_level=archive gives better performance than minimal - why?
Date: Mon, 16 Jan 2012 17:35:53 -0500
Message-ID: <4F14A649.5060501@2ndQuadrant.com> (raw)
In-Reply-To: <4F0F6A02.3000403@fuzzy.cz>
References: <4F0F6A02.3000403@fuzzy.cz>
On 01/12/2012 06:17 PM, Tomas Vondra wrote:
> I've run a series fo pgbench benchmarks with the aim to see the effect
> of moving the WAL logs to a separate drive, and one thing that really
> surprised me is that the archive log level seems to give much better
> performance than minimal log level.
How repeatable is this? If you always run minimal first and then
archive, that might be the actual cause of the difference. In this
situation I would normally run this 12 times, with this sort of pattern:
minimal
minimal
minimal
archive
archive
archive
minimal
minimal
minimal
archive
archive
archive
To make sure the difference wasn't some variation on "gets slower after
each run". pgbench suffers a lot from problems in that class.
--
Greg Smith 2ndQuadrant US greg@2ndQuadrant.com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.com
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To: pgsql-performance@postgresql.org
Cc: greg@2ndQuadrant.com
Subject: Re: wal_level=archive gives better performance than minimal - why?
In-Reply-To: <4F14A649.5060501@2ndQuadrant.com>
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