Re: Planner selects slow "Bitmap Heap Scan" when "Index Scan" is faster

From: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
To: <pgsql-performance(at)postgresql(dot)org>,"Kim Hansen" <kim(at)rthansen(dot)dk>
Subject: Re: Planner selects slow "Bitmap Heap Scan" when "Index Scan" is faster
Date: 2012-04-05 15:34:36
Message-ID: 4F7D753C0200002500046BF5@gw.wicourts.gov
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Kim Hansen <kim(at)rthansen(dot)dk> wrote:

> I have a query where the planner makes a wrong cost estimate, it
> looks like it underestimates the cost of a "Bitmap Heap Scan"
> compared to an "Index Scan".

> What can I do to fix the cost estimate?

Could you try running the query with cpu_tuple_cost = 0.05 and let
us know how that goes?

-Kevin

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