From: Tom Lane <tgl@sss.pgh.pa.us>
To: Rolf Østvik <rolfostvik@yahoo.no>
Cc: pgsql-performance@postgresql.org
Subject: Re: Worse perfomance on 8.2.0 than on 7.4.14
Date: Tue, 02 Jan 2007 10:07:24 -0500
Message-ID: <3425.1167750444@sss.pgh.pa.us> (raw)
In-Reply-To: <20070102124518.1503.qmail@web26301.mail.ukl.yahoo.com>
References: <20070102124518.1503.qmail@web26301.mail.ukl.yahoo.com>
=?iso-8859-1?q?Rolf=20=D8stvik?= <rolfostvik@yahoo.no> writes:
> If you (Tom) still want me to do the following steps
> then please tell me.
Please --- I'm still curious why the estimated cost changed so much from
7.4 to 8.2. I can believe a marginal change in cost leading to a plan
switch, but comparing the total-cost numbers shows that 8.2 must think
that indexscan is a whole lot more expensive than 7.4 did, which seems
odd. For the most part 8.2 ought to think nestloop-with-inner-indexscan
is cheaper than 7.4 did, because we now account for caching effects across
repeated iterations of the inner scan.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, rolfostvik@yahoo.no
Subject: Re: Worse perfomance on 8.2.0 than on 7.4.14
In-Reply-To: <3425.1167750444@sss.pgh.pa.us>
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