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From: Tom Lane <tgl@sss.pgh.pa.us>
To: David Kerr <dmk@mr-paradox.net>
cc: pgsql-performance@postgresql.org
Subject: Re: Drop statistics?
In-reply-to: <20120622170755.GB93663@mr-paradox.net>
References: <20120622170755.GB93663@mr-paradox.net>
Comments: In-reply-to David Kerr <dmk@mr-paradox.net>
	message dated "Fri, 22 Jun 2012 10:07:56 -0700"
Date: Fri, 22 Jun 2012 13:27:51 -0400
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David Kerr <dmk@mr-paradox.net> writes:
> I'm trying to work through a root cause on a performance problem. I'd like to
> be able to "show" that a problem was fixed by analyzing the table.

> what i've done is
> set default_statistics_target=1
> analyze <Table>

> That gets rid of most of the rows in pg_stats, but i'm still getting decent performance.

I usually do something like

DELETE FROM pg_statistic WHERE starelid = 'foo'::regclass;

(you need to be superuser to be allowed to do this).

You may need to keep an eye on whether auto-analyze is coming along and
undoing what you did, too.

			regards, tom lane