Re: index in desc order - Mailing list pgsql-general

From Michal Politowski
Subject Re: index in desc order
Date
Msg-id 20101102142157.GA12638@meep.pl
Whole thread Raw
In response to Re: index in desc order  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: index in desc order  (Dimitri Fontaine <dimitri@2ndQuadrant.fr>)
List pgsql-general
On Tue,  2 Nov 2010 10:10:19 -0400, Tom Lane wrote:
> Szymon Guz <mabewlun@gmail.com> writes:
> > On 2 November 2010 10:36, AI Rumman <rummandba@gmail.com> wrote:
> >> Is it possible to create an index in descending order?
>
> > create index i on t(i desc);
>
> Note that there is actually no point at all in such a declaration.
> The planner is perfectly capable of using backwards indexscans at
> need, so the above index doesn't do anything you couldn't do with
> a regular ascending-order index.

Cannot there be a (system/hardware) setup where there is a perceptible
performance difference between forward and backward index scans?

--
Michał Politowski
Talking has been known to lead to communication if practiced carelessly.

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