| From: | Greg Smith <gsmith(at)gregsmith(dot)com> |
|---|---|
| To: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
| Cc: | Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Andrew Dunstan <andrew(at)dunslane(dot)net>, Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Alan Li <ali(at)truviso(dot)com> |
| Subject: | Re: 8.4 open item: copy performance regression? |
| Date: | 2009-06-21 06:45:04 |
| Message-ID: | alpine.GSO.2.01.0906210241020.7754@westnet.com |
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| Lists: | pgsql-hackers |
On Sat, 20 Jun 2009, Simon Riggs wrote:
> I would suggest that we check how much WAL has been written. There may
> be a secondary effect or a different regression hidden in these results.
What's the easiest way to do that? My first thought was to issue a
checkpoint before the test (which is a good idea to make each test
consistent anyway), save the output from pg_controldata, test, checkpoint,
and look at the control data again. This seems kind of clunky though, but
still better than trolling through the OS statistics for the data. Any
clever ideas for a better way to measure bytes of WAL written during a
particular chunk of code? We may need some sort of checkpoint/sync after
the test to get correct results, because I've noticed that the tests I run
sometimes continue writing out buffers for a few seconds after the test
time is finished.
--
* Greg Smith gsmith(at)gregsmith(dot)com http://www.gregsmith.com Baltimore, MD
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