| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Ashutosh Bapat <ashutosh(dot)bapat(dot)oss(at)gmail(dot)com> |
| Cc: | David Christensen <david+pg(at)pgguru(dot)net>, Richard Guo <guofenglinux(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Reuse child_relids in try_partitionwise_join was Re: Assert failure on bms_equal(child_joinrel->relids, child_joinrelids) |
| Date: | 2024-06-06 16:30:39 |
| Message-ID: | CA+TgmoZUKhE_ZM0LrphpUwmQJtZk-rOo8Qtto1znSG+PKrPm2Q@mail.gmail.com |
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On Wed, Jun 5, 2024 at 3:48 AM Ashutosh Bapat
<ashutosh(dot)bapat(dot)oss(at)gmail(dot)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
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