From: Tom Lane <tgl@sss.pgh.pa.us>
To: Susan Russo <russo@morgan.harvard.edu>
Cc: pgsql-performance@postgresql.org
Cc: harvsys@morgan.harvard.edu
Subject: Re: specific query (not all) on Pg8 MUCH slower than Pg7
Date: Tue, 08 May 2007 10:48:25 -0400
Message-ID: <1160.1178635705@sss.pgh.pa.us> (raw)
In-Reply-To: <200705081418.l48EIY8V026360@larrys.harvard.edu>
References: <200705081418.l48EIY8V026360@larrys.harvard.edu>
Susan Russo <russo@morgan.harvard.edu> writes:
> Despite numerous efforts, we're unable to solve a severe performance limitation between Pg 7.3.2
> and Pg 8.1.4.
> The query and 'explain analyze' plan below, runs in
> 26.20 msec on Pg 7.3.2, and
> 2463.968 ms on Pg 8.1.4,
You're not getting the indexscan optimization of the LIKE clause, which
is most likely due to having initdb'd the 8.1 installation in something
other than C locale. You can either redo the initdb in C locale (which
might be a good move to fix other inconsistencies from the 7.3 behavior
you're used to) or create a varchar_pattern_ops index on the column(s)
you're using LIKE with.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, russo@morgan.harvard.edu, harvsys@morgan.harvard.edu
Subject: Re: specific query (not all) on Pg8 MUCH slower than Pg7
In-Reply-To: <1160.1178635705@sss.pgh.pa.us>
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