Re: Speeding up select distinct

From: Laurent Martelli <laurent(at)aopsys(dot)com>
To: Rod Taylor <pg(at)rbt(dot)ca>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Speeding up select distinct
Date: 2005-03-16 18:31:14
Message-ID: 87br9j4f4d.fsf@stan.aopsys
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>>>>> "Rod" == Rod Taylor <pg(at)rbt(dot)ca> writes:

Rod> On Wed, 2005-03-16 at 18:58 +0100, Laurent Martelli wrote:
>> Consider this query:
>>
>> SELECT distinct owner from pictures;

Rod> The performance has nothing to do with the number of rows
Rod> returned, but rather the complexity of calculations and amount
Rod> of data to sift through in order to find it.

Yes, but I thought that an index might be able to know what distinct
values there are and help optime that query very much.

--
Laurent Martelli
laurent(at)aopsys(dot)com Java Aspect Components
http://www.aopsys.com/ http://jac.objectweb.org

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