Re: Timestamp indicies not being used!

From: Andreas Kretschmer <akretschmer(at)spamfence(dot)net>
To: pgsql-general(at)postgresql(dot)org
Subject: Re: Timestamp indicies not being used!
Date: 2009-07-19 12:56:04
Message-ID: 20090719125604.GA7124@tux
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Sam Mason <sam(at)samason(dot)me(dot)uk> wrote:

> On Sun, Jul 19, 2009 at 11:15:39AM +0100, Pedro Doria Meunier wrote:
> > I have a table ~18M rows with a 'timestamp with time zone' column. It's
> > indexed thus:
> >
> > CREATE INDEX my_table_timestamp_idx
> > ON my_table
> > USING btree
> > (zulu_timestamp);
>
> Based on your query, I think you want a multi-column index---probably on
> (id,zulu_timestamp).
>
> The problem with just having an index on either column is that it's
> difficult to combine them and PG hence just thinks that it will be

Since 8.1 PG can do an bitmap index scan using both indexes...

Andreas
--
Really, I'm not out to destroy Microsoft. That will just be a completely
unintentional side effect. (Linus Torvalds)
"If I was god, I would recompile penguin with --enable-fly." (unknown)
Kaufbach, Saxony, Germany, Europe. N 51.05082°, E 13.56889°

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