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

From: Marinos Yannikos <mjy(at)geizhals(dot)at>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: 1-/2-dimensional indexes for common columns, rationale?
Date: 2008-03-26 15:15:20
Message-ID: 47EA6888.2050506@geizhals.at (view raw or flat)
Thread:
Lists: pgsql-performance
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...

-mjy



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