From: Tom Lane <tgl@sss.pgh.pa.us>
To: David Rowley <dgrowleyml@gmail.com>
Cc: william.duclot@gmail.com, PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>
Subject: Re: BUG #17540: Prepared statement: PG switches to a generic query plan which is consistently much slower
Date: Wed, 06 Jul 2022 23:50:48 -0400
Message-ID: <2740652.1657165848@sss.pgh.pa.us> (raw)
In-Reply-To: <CAApHDvqhr1eU9v42w5gt_gL=G15pB9RBpAH_Jmg7eDU6iZ_2zg@mail.gmail.com>
References: <17540-7aa1855ad5ec18b4@postgresql.org>
<CAApHDvqRR81Dvur_zcrY+RsKxv_e8uDpJ2xxAPMmnfgDY7VNew@mail.gmail.com>
<2732256.1657163219@sss.pgh.pa.us>
<CAApHDvqhr1eU9v42w5gt_gL=G15pB9RBpAH_Jmg7eDU6iZ_2zg@mail.gmail.com>
David Rowley <dgrowleyml@gmail.com> writes:
> Anyway, I've no current plans to take the attached any further. I
> think it'll be better to pursue your NULLable-Var stuff and see if we
> can do something more generic like remove provably redundant NullTests
> from baserestrictinfo.
Yeah, I suspect that the way forward is to allow
preprocess_minmax_aggregates to do what it does now, and then
remove the IS NOT NULL clause again later when we have the
info available to let us do that in a generic way.
In any case, as you said, it's just a band-aid that happens to
help in this exact scenario. It's not doing much for the bad
cost estimation that's the root of the problem.
regards, tom lane
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To: pgsql-bugs@postgresql.org
Cc: tgl@sss.pgh.pa.us, dgrowleyml@gmail.com, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #17540: Prepared statement: PG switches to a generic query plan which is consistently much slower
In-Reply-To: <2740652.1657165848@sss.pgh.pa.us>
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