From: Tom Lane <tgl@sss.pgh.pa.us>
To: Etsuro Fujita <fujita.etsuro@lab.ntt.co.jp>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Pg Hackers <pgsql-hackers@postgresql.org>
Subject: Re: Oddity with parallel safety test for scan/join target in grouping_planner
Date: Mon, 11 Mar 2019 10:46:12 -0400
Message-ID: <22068.1552315572@sss.pgh.pa.us> (raw)
In-Reply-To: <5C85F24E.4050404@lab.ntt.co.jp>
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<32401.1552277190@sss.pgh.pa.us>
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<5C85F24E.4050404@lab.ntt.co.jp>
Etsuro Fujita <fujita.etsuro@lab.ntt.co.jp> writes:
> (2019/03/11 14:14), Tom Lane wrote:
>> Seems to me it's the other way around: the final target would include
>> all functions invoked in the grouping target plus maybe some more.
>> So a non-parallel-safe grouping target implies a non-parallel-safe
>> final target, but not vice versa.
> I mean the final *scan/join* target, not the final target.
Oh, of course. Yup, I was too tired last night :-(. So this is
just a plan-quality problem not a wrong-answer problem.
However, I'd still argue for back-patching into v11, on the grounds
that this is a regression from v10. The example you just gave does
produce the desired plan in v10, and I think it's more likely that
people would complain about a regression from v10 than that they'd
be unhappy because we changed it between 11.2 and 11.3.
regards, tom lane
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To: pgsql-hackers@postgresql.org
Cc: tgl@sss.pgh.pa.us, fujita.etsuro@lab.ntt.co.jp, robertmhaas@gmail.com
Subject: Re: Oddity with parallel safety test for scan/join target in grouping_planner
In-Reply-To: <22068.1552315572@sss.pgh.pa.us>
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