| From: | "A(dot) Kretschmer" <andreas(dot)kretschmer(at)schollglas(dot)com> |
|---|---|
| To: | pgsql-general(at)postgresql(dot)org |
| Subject: | Re: Database Select Slow |
| Date: | 2007-08-10 12:42:48 |
| Message-ID: | 20070810124247.GA6206@a-kretschmer.de |
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| Lists: | pgsql-general |
am Fri, dem 10.08.2007, um 17:46:11 +0800 mailte carter ck folgendes:
> Hi all,
>
> I am facing a performance issue here. Whenever I do a count(*) on a table
> that contains about 300K records, it takes few minutes to complete. Whereas
> my other application which is counting > 500K records just take less than
> 10 seconds to complete.
>
> I have indexed all the essential columns and still it does not improve the
> speed.
Indexes don't help in this case, a 'select count(*)' forces a seq. scan.
Do you realy need this information? An estimate for the number of rows
can you find in the system catalog (reltuples in pg_class, see
http://www.postgresql.org/docs/current/interactive/catalog-pg-class.html)
Andreas
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Andreas Kretschmer
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