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Re: 1-/2-dimensional indexes for common columns, rationale?

From: "A(dot) Kretschmer" <andreas(dot)kretschmer(at)schollglas(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: 1-/2-dimensional indexes for common columns, rationale?
Date: 2008-03-26 15:25:18
Message-ID: 20080326152518.GI27264@a-kretschmer.de (view raw or flat)
Thread:
Lists: pgsql-performance
am  Wed, dem 26.03.2008, um 16:15:20 +0100 mailte Marinos Yannikos folgendes:
> A. Kretschmer schrieb:
> >>create index foo1 on bla (a);
> >>create index foo2 on bla (b);
> >>create index foo3 on bla (a,b);
> >>[...]
> >
> >Which version do you have? Since 8.1 pg can use a so called 'bitmap
> >index scan', because of this feature i guess you don't need the index
> >foo3. (if you have 8.1 or higher)
> 
> 8.3.1 - foo3 is being used though in presence of both foo1 and foo2, so 
> I'd suppose that it's a better choice even with bitmap index scan 
> available...

Maybe...


Andreas
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Andreas Kretschmer
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