Re: for/loop performance in plpgsql ? - Mailing list pgsql-performance

From Tom Lane
Subject Re: for/loop performance in plpgsql ?
Date
Msg-id 20274.1037714642@sss.pgh.pa.us
Whole thread Raw
In response to Re: for/loop performance in plpgsql ?  (Federico /* juri */ Pedemonte <fepede@inwind.it>)
List pgsql-performance
Federico /* juri */ Pedemonte <fepede@inwind.it> writes:
> On Tue, Nov 19, 2002 at 12:23:56AM -0500, Tom Lane wrote:
>> The planner has to fall back to default selectivity estimates when it's
>> looking at queries involving plpgsql variables (since it can't know
>> their actual values in advance).  I suspect your problem is related to
>> an inaccurate default estimate.

> mmm... does it mean that i can't do anything about that ?

A brute-force solution is to use EXECUTE so that the query is re-planned
each time, with the planner seeing constants instead of variables
compared to the column values.

            regards, tom lane

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