From: | "Steinar H(dot) Gunderson" <sgunderson(at)bigfoot(dot)com> |
---|---|
To: | Susan Russo <russo(at)morgan(dot)harvard(dot)edu> |
Cc: | pgsql-performance(at)postgresql(dot)org, harvsys(at)morgan(dot)harvard(dot)edu |
Subject: | Re: specific query (not all) on Pg8 MUCH slower than Pg7 |
Date: | 2007-05-08 14:48:34 |
Message-ID: | 20070508144834.GA5678@uio.no |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-performance |
On Tue, May 08, 2007 at 10:18:34AM -0400, Susan Russo wrote:
> explain analyze output on Pg7.3.2:
>
> -> Index Scan using dbxref_idx2 on dbxref dx (cost=0.00..5.83 rows=1 width=21) (actual time=25.58..25.58 rows=0 loops=1)
> Index Cond: ((accession >= 'AY851043'::character varying) AND (accession < 'AY851044'::character varying))
> Filter: (accession ~~ 'AY851043%'::text)
>
> explain analyze output on Pg8.1.4:
>
> -> Seq Scan on dbxref dx (cost=0.00..47923.91 rows=1 width=21) (actual time=2463.646..2463.646 rows=0 loops=1)
> Filter: ((accession)::text ~~ 'AY851043%'::text)
This is almost all of your cost. Did you perchance initdb the 8.1.4 cluster
in a non-C locale? You could always try
CREATE INDEX test_index ON dbxref (accession varchar_pattern_ops);
which would create an index that might be more useful for your LIKE query,
even in a non-C locale.
/* Steinar */
--
Homepage: http://www.sesse.net/
From | Date | Subject | |
---|---|---|---|
Next Message | Richard Broersma Jr | 2007-05-08 14:54:48 | Re: specific query (not all) on Pg8 MUCH slower than Pg7 |
Previous Message | Tom Lane | 2007-05-08 14:48:25 | Re: specific query (not all) on Pg8 MUCH slower than Pg7 |