Re: Reuse child_relids in try_partitionwise_join was Re: Assert failure on bms_equal(child_joinrel->relids, child_joinrelids) - Mailing list pgsql-hackers

On Wed, Jun 5, 2024 at 3:48 AM Ashutosh Bapat
<ashutosh.bapat.oss@gmail.com> wrote:
> Here's planning time measurements.
>  num_joins | master (ms) | patched (ms) | change in planning time (ms) | change in planning time
> -----------+-------------+--------------+------------------------------+---------------------------------------
>          2 |      187.86 |       177.27 |                        10.59 |                                  5.64%
>          3 |      721.81 |       758.80 |                       -36.99 |                                 -5.12%
>          4 |     2239.87 |      2236.19 |                         3.68 |                                  0.16%
>          5 |     6830.86 |      7027.76 |                      -196.90 |                                 -2.88%

I find these results concerning. Why should the planning time
sometimes go up? And why should it go up for odd numbers of joinrels
and down for even numbers of joinrels? I wonder if these results are
really correct, and if they are, I wonder what could account for such
odd behavior

--
Robert Haas
EDB: http://www.enterprisedb.com