Re: MIN() performance regression 8.0 -> 8.1 - Mailing list pgsql-hackers

From Tom Lane
Subject Re: MIN() performance regression 8.0 -> 8.1
Date
Msg-id 12394.1133751935@sss.pgh.pa.us
Whole thread Raw
In response to MIN() performance regression 8.0 -> 8.1  (Paul Lindner <lindner@inuus.com>)
List pgsql-hackers
Paul Lindner <lindner@inuus.com> writes:
> I believe I've found a performance regression between 8.0 and 8.1 for
> some cases.  For some queries it appears that the old MIN() ran much
> faster than the new optimized MIN().

When you are complaining about planner mistakes, showing EXPLAIN rather
than EXPLAIN ANALYZE output is an entirely ineffective way of making
your point.

I suspect the problem is that there is a correlation between the
moo_summary_date and moo_summary_b_id columns, which the planner
will not realize --- is that the case?
        regards, tom lane


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