Re: [HACKERS] Runtime Partition Pruning

On 22 December 2017 at 12:45, Robert Haas <robertmhaas@gmail.com> wrote:
> PREPARE q3 (int, int) AS SELECT * FROM unpartitioned_table WHERE
> partkey BETWEEN $1 AND $2;
>
> ...that has to decide whether to use an index.  And to do that it has
> to estimate what fraction of the table will match the BETWEEN clause.
> That may be an uninformed guess, but it guesses something.  We
> probably want to do something here that makes the guess for a
> partitioned_table similar to the guess for an unpartitioned_table.

Are you considering some sort of clauselist_selectivity() estimate on
the given parameters and comparing that to the same selectivities that
were determined for the previous custom plans?

-- 
 David Rowley                   http://www.2ndQuadrant.com/
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