From: Tom Lane <tgl@sss.pgh.pa.us>
To: Richard Huxton <dev@archonet.com>
Cc: Brian Herlihy <btherl@yahoo.com.au>
Cc: pgsql-performance@postgresql.org
Subject: Re: Spotting planner errors (was Re: Query planner is using wrong index.)
Date: Fri, 07 Apr 2006 11:12:52 -0400
Message-ID: <12067.1144422772@sss.pgh.pa.us> (raw)
In-Reply-To: <4436805A.1040507@archonet.com>
References: <20060407064108.49532.qmail@web52315.mail.yahoo.com>
<11739.1144420493@sss.pgh.pa.us>
<4436805A.1040507@archonet.com>
Richard Huxton <dev@archonet.com> writes:
> Tom - does the planner/executor know it's got row estimates wrong? That
> is, if I'm not running an EXPLAIN ANALYSE is there a point at which we
> could log "planner estimate for X out by factor of Y"?
Not at the moment, but you could certainly imagine changing the executor
to count rows even without EXPLAIN ANALYZE, and then complain during
plan shutdown.
Not sure how helpful that would be; there would be a lot of noise from
common cases such as executing underneath a LIMIT node.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, dev@archonet.com, btherl@yahoo.com.au
Subject: Re: Spotting planner errors (was Re: Query planner is using wrong index.)
In-Reply-To: <12067.1144422772@sss.pgh.pa.us>
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