Can this query be optimized?

From: Claus Heiko Niesen <cniesen(at)gmx(dot)net>
To: pgsql-sql(at)postgresql(dot)org
Subject: Can this query be optimized?
Date: 2001-11-07 21:00:40
Message-ID: 5.1.0.14.2.20011107144418.00a83b68@pop.gmx.net
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I'm stuck optimizing the following query:

select distinct extract(year from date) as year, extract(month from date)
as month, date from week_pics order by date desc;

The table "week_pics" contains the column "date" which is indexed in
descending order. Unfortunately postresql isn't using the index since I'm
using extract and order by the resulting values. Instead postgresql will
sort the result set. To order by the date implies that the date needs to
be in my select statement, which interferes with uniqueness of the
year-month pair.

Is there anything I could do to optimize this query besides breaking the
date into three separate columns?

Claus

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