Re: Join over two tables of 50K records takes 2 hours - Mailing list pgsql-performance

From Tom Lane
Subject Re: Join over two tables of 50K records takes 2 hours
Date
Msg-id 13425.1318567068@sss.pgh.pa.us
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In response to Join over two tables of 50K records takes 2 hours  (Svetlin Manavski <svetlin.manavski@gmail.com>)
Responses Re: Join over two tables of 50K records takes 2 hours  (Svetlin Manavski <svetlin.manavski@gmail.com>)
List pgsql-performance
Svetlin Manavski <svetlin.manavski@gmail.com> writes:
> I am running 9.03 with the settings listed below. I have a prohibitively
> slow query in an application which has an overall good performance:

It's slow because the planner is choosing a nestloop join on the
strength of its estimate that there's only a half dozen rows to be
joined.  You need to figure out why those rowcount estimates are so bad.
I suspect that you've shot yourself in the foot by raising
autovacuum_analyze_threshold so high --- most likely, none of those
tables have ever gotten analyzed.  And what's with the high
autovacuum_naptime setting?  You might need to increase
default_statistics_target too, but first see if a manual ANALYZE makes
things better.

            regards, tom lane

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