Tom,
Now, while index scans (for indexes on disk) aren't 100% sequential
reads, it seems like we should be increasing (substantially) the
estimated cost of reverse index scans if the index is likely to be on
disk. No?
AFAICS this is already folded into random_page_cost.
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.
--
Josh Berkus
PostgreSQL Experts Inc.
www.pgexperts.com
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