| From: | Greg Smith <greg(at)2ndQuadrant(dot)com> |
|---|---|
| To: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: wal_level=archive gives better performance than minimal - why? |
| Date: | 2012-01-16 22:35:53 |
| Message-ID: | 4F14A649.5060501@2ndQuadrant.com |
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| Lists: | pgsql-performance |
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(at)2ndQuadrant(dot)com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.com
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