Re: Checkpointer split has broken things dramatically (was Re: DELETE vs TRUNCATE explanation)
David Fetter <david@fetter.org>
From: David Fetter <david@fetter.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Robert Haas <robertmhaas@gmail.com>, Jeff Janes <jeff.janes@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, Daniel Farina <daniel@heroku.com>, Craig Ringer <ringerc@ringerc.id.au>, Harold A. Giménez <harold.gimenez@gmail.com>
Date: 2012-07-23T04:37:33Z
Lists: pgsql-hackers, pgsql-performance
On Tue, Jul 17, 2012 at 06:56:50PM -0400, Tom Lane wrote: > Robert Haas <robertmhaas@gmail.com> writes: > > On Mon, Jul 16, 2012 at 3:18 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote: > >> BTW, while we are on the subject: hasn't this split completely > >> broken the statistics about backend-initiated writes? > > > Yes, it seems to have done just that. > > This implies that nobody has done pull-the-plug testing on either > HEAD or 9.2 since the checkpointer split went in (2011-11-01), > because even a modicum of such testing would surely have shown that > we're failing to fsync a significant fraction of our write traffic. > > Furthermore, I would say that any performance testing done since > then, if it wasn't looking at purely read-only scenarios, isn't > worth the electrons it's written on. In particular, any performance > gain that anybody might have attributed to the checkpointer splitup > is very probably hogwash. > > This is not giving me a warm feeling about our testing practices. Is there any part of this that the buildfarm, or some other automation framework, might be able to handle? Cheers, David. -- David Fetter <david@fetter.org> http://fetter.org/ Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter Skype: davidfetter XMPP: david.fetter@gmail.com iCal: webcal://www.tripit.com/feed/ical/people/david74/tripit.ics Remember to vote! Consider donating to Postgres: http://www.postgresql.org/about/donate
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API reference →
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Scan the buffer pool just once, not once per fork, during relation drop.
- ece01aae4792 9.2.0 cited