From: Tomas Vondra <tomas@vondra.me>
To: David Rowley <dgrowleyml@gmail.com>
Cc: Andrei Lepikhov <lepihov@gmail.com>
Cc: tharakan@gmail.com, pgsql-bugs@lists.postgresql.org, PG Bug reporting form <noreply@postgresql.org>
Cc: Alexander Korotkov <aekorotkov@gmail.com>
Subject: Re: BUG #18885: ERROR: corrupt MVNDistinct entry - 2
Date: Mon, 21 Apr 2025 11:41:19 +0200
Message-ID: <afb124fc-f595-4681-bae8-e11c1ff52305@vondra.me> (raw)
In-Reply-To: <CAApHDvrk3jYTe2WgB5ZaTKC3JHgVWhK3FD1gy7A3OYmrQH3+RQ@mail.gmail.com>
References: <18885-da51324078588253@postgresql.org>
<f485c85f-9796-467e-81fe-43e8127cbb35@vondra.me>
<CAApHDvocZCUhM9W9mJ39d6oQz7ePKoqFnao_347mvC-A7QatcQ@mail.gmail.com>
<048f142e-18eb-4416-b7c7-b1398e667b3c@gmail.com>
<769393be-6fea-435e-8316-66546c6f4a49@vondra.me>
<CAApHDvrk3jYTe2WgB5ZaTKC3JHgVWhK3FD1gy7A3OYmrQH3+RQ@mail.gmail.com>
On 4/16/25 06:11, David Rowley wrote:
> On Wed, 16 Apr 2025 at 01:16, Tomas Vondra <tomas@vondra.me> wrote:
>> In any case, such rework seems out of scope for PG18 - it's much more
>> than a fix for the bug.
>
> This is the reason I stopped short of adjusting the code in the patch
> I proposed in [1]. Speaking of which, do you have any views on that?
> It seems much more likely that someone would have caught the issue
> being reported here when writing the patch or during review if there
> was some sort of documentation to mention the function can't handle
> duplicate GroupVarInfos.
>
> I'll look at that patch again in the next few days with aims to push
> it unless someone has something to say about it.
>
Yeah, you're right the estimate_multivariate_ndistinct() comments should
have mentioned that the GroupVarInfos are expected to be unique ... and
perhaps there could have been some assert to check that.
regards
--
Tomas Vondra
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To: pgsql-bugs@postgresql.org
Cc: tomas@vondra.me, dgrowleyml@gmail.com, lepihov@gmail.com, noreply@postgresql.org, aekorotkov@gmail.com
Subject: Re: BUG #18885: ERROR: corrupt MVNDistinct entry - 2
In-Reply-To: <afb124fc-f595-4681-bae8-e11c1ff52305@vondra.me>
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