| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | David Rowley <dgrowleyml(at)gmail(dot)com> |
| Cc: | william(dot)duclot(at)gmail(dot)com, PostgreSQL mailing lists <pgsql-bugs(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: BUG #17540: Prepared statement: PG switches to a generic query plan which is consistently much slower |
| Date: | 2022-07-07 03:50:48 |
| Message-ID: | 2740652.1657165848@sss.pgh.pa.us |
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| Lists: | pgsql-bugs pgsql-hackers |
David Rowley <dgrowleyml(at)gmail(dot)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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