Re: Shouldn't the planner have a higher cost for reverse index scans?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Josh Berkus <josh(at)agliodbs(dot)com>
Cc: postgres performance list <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Shouldn't the planner have a higher cost for reverse index scans?
Date: 2009-04-10 17:19:36
Message-ID: 25703.1239383976@sss.pgh.pa.us
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Josh Berkus <josh(at)agliodbs(dot)com> writes:
> Not as far as I can tell. It looks to me like the planner is assuming
> that a forwards index scan and a reverse index scan will have the same
> cost.

Right, because they do. If you think otherwise, demonstrate it.
(bonnie tests approximating a reverse seqscan are not relevant
to the performance of indexscans.)

regards, tom lane

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