From: | David Rowley <dgrowleyml(at)gmail(dot)com> |
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To: | sk(at)zsrv(dot)org, pgsql-bugs(at)lists(dot)postgresql(dot)org |
Subject: | Re: BUG #17885: slow planning constraint_exclusion |
Date: | 2023-04-04 22:16:28 |
Message-ID: | CAApHDvphHUroVaGHnCtXF6S39_VkE2uL0X2F9HNyuQkfshhyzg@mail.gmail.com |
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Lists: | pgsql-bugs |
On Wed, 5 Apr 2023 at 05:14, PG Bug reporting form
<noreply(at)postgresql(dot)org> wrote:
> Increasing the number of partitions or size of "not in" list further
> increases planning time. Reproduced on today's HEAD 16dev too. I found time
> is wasted somewhere in relation_excluded_by_constraints.
How did you come to the conclusion that the time is wasted?
> If I disable
> constraint_exclusion completely, then the planning time drops to a few
> milliseconds.
We still run relation_excluded_by_constraints() after partition
pruning only the remaining partitions. I believe there were some
cases that we still didn't prune that relation_excluded_by_constraints
was able to eliminate. I don' recall the exact details of what those
cases are. I believe the call to relation_excluded_by_constraints()
was kept due to this.
You may want to just switch it off if it's too slow for you. I don't
think anything you've shown here is worthy of being classed as a bug.
David
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