| From: | Andreas Kretschmer <akretschmer(at)despammed(dot)com> |
|---|---|
| To: | pgsql-sql(at)postgresql(dot)org |
| Cc: | Andreas Kretschmer <akretschmer(at)despammed(dot)com> |
| Subject: | Re: [despammed] question about index |
| Date: | 2004-12-16 14:15:57 |
| Message-ID: | 20041216141557.GA17096@Pinguin.wug-glas.de |
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| Lists: | pgsql-sql |
am 16.12.2004, um 8:10:25 -0600 mailte Bruno Wolff III folgendes:
> On Thu, Dec 16, 2004 at 12:01:39 +0100,
> Andreas Kretschmer <akretschmer(at)despammed(dot)com> wrote:
> > >
> > > considering that almost 70% of the rows will be with 'VALUE1', 20%
> > > will be with 'VALUE2' and 10% will be with 'VALUE3' on the average.
> > >
> > > should I create an index to speedup the counts or not ?
> >
> > Yes.
>
> Indexes will probably not help in this case. Even when looking at 10% of
> the rows, a sequential scan is still going to be faster than an index
> scan in most cases.
Okay.
Andreas
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Andreas Kretschmer (Kontakt: siehe Header)
Tel. NL Heynitz: 035242/47212
GnuPG-ID 0x3FFF606C http://wwwkeys.de.pgp.net
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