Hi,
>You could always try
>
> CREATE INDEX test_index ON dbxref (accession varchar_pattern_ops);
WOW! we're now at runtime 0.367ms on Pg8
Next step is to initdb w/C Locale (tonight) (Thanks Tom et al.!).
Thanks again - will report back soon.
Susan
>From [EMAIL PROTECTED] Tue May 8 10:49:14 2007
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Date: Tue, 8 May 2007 16:48:34 +0200
From: "Steinar H. Gunderson" <[EMAIL PROTECTED]>
To: Susan Russo <[EMAIL PROTECTED]>
Cc: pgsql-performance@postgresql.org, [EMAIL PROTECTED]
Subject: Re: [PERFORM] specific query (not all) on Pg8 MUCH slower than Pg7
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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 */
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Homepage: http://www.sesse.net/
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