From: Alexander Staubo <alex@bengler.no>
To: Kevin Grittner <kgrittn@ymail.com>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: Bad query plan with high-cardinality column
Date: Fri, 22 Feb 2013 22:34:21 +0100
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On Friday, February 22, 2013 at 21:47 , Kevin Grittner wrote:
> I suspect you would be better off without those two indexes, and
> instead having an index on (conversation_id, created_at). Not just
> for the query you show, but in general.
Indeed, that solved it, thanks!
> In my experience these problems come largely from the planner not
> knowing the cost of dealing with each tuple. I see a lot less of
> this if I raise cpu_tuple_cost to something in the 0.03 to 0.05
> range.
Is this something I can just frob a bit without worrying about it adversely impacting database performance across the board, or should I be very careful and do lots of testing on a staging box first?
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To: pgsql-performance@postgresql.org
Cc: alex@bengler.no, kgrittn@ymail.com
Subject: Re: Bad query plan with high-cardinality column
In-Reply-To: <D0D7098559DD470B9C2DE753E74B83E4@gmail.com>
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