From: Tom Lane <tgl@sss.pgh.pa.us>
To: Daniel Burbridge <Daniel.Burbridge@publishingtechnology.com>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: Prepared statements slow in 9.2 still (bad query plan)
Date: Sun, 28 Oct 2012 11:06:21 -0400
Message-ID: <12200.1351436781@sss.pgh.pa.us> (raw)
In-Reply-To: <CA9A03D82318FE41825E250D9880D959B3BFD5@maple.VISTACOMP.COM>
References: <CA9A03D82318FE41825E250D9880D959B3BFD5@maple.VISTACOMP.COM>
Daniel Burbridge <Daniel.Burbridge@publishingtechnology.com> writes:
> I have a problem with prepared statements choosing a bad query plan - I was hoping that 9.2 would have eradicated the problem :(
9.2 will only pick the "right" plan if that plan's estimated cost is a
good bit cheaper than the "wrong" parameterized plan. In this case,
not only is there not a lot of difference, but the difference is in the
wrong direction. You need to fix that --- perhaps increasing stats
targets would help?
A more radical question is whether you have a well-chosen set of indexes
in the first place. These two seem a bit odd, and certainly not
terribly well matched to this query.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, Daniel.Burbridge@publishingtechnology.com
Subject: Re: Prepared statements slow in 9.2 still (bad query plan)
In-Reply-To: <12200.1351436781@sss.pgh.pa.us>
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