Re: Remove redundant DISTINCT when GROUP BY already guarantees uniqueness

From: Ilia Evdokimov <ilya(dot)evdokimov(at)tantorlabs(dot)com>
To: Antonin Houska <ah(at)cybertec(dot)at>
Cc: andres(at)taylor(dot)se, pgsql-hackers(at)lists(dot)postgresql(dot)org, David Rowley <dgrowleyml(at)gmail(dot)com>, zhihuifan1213(at)163(dot)com, guofenglinux(at)gmail(dot)com
Subject: Re: Remove redundant DISTINCT when GROUP BY already guarantees uniqueness
Date: 2026-07-23 20:39:44
Message-ID: d695e06c-dc0e-460f-84e3-077acb6132a2@tantorlabs.com
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On 7/23/26 18:23, Antonin Houska wrote:

> Ilia Evdokimov<ilya(dot)evdokimov(at)tantorlabs(dot)com> wrote:
>
>> Thanks a lot for detailed review.
>>
>> Since there's already patch work on the UniqueKeys approach, I think it make
>> sense to keep building on that rather than staring over. Thanks for rebase
>> onto master. I attached 0001-patch with it.
>>
>> CC: Antonin, Andy
> Not sure if you noticed that, related work was posted yesterday:
>
> https://www.postgresql.org/message-id/CAMbWs4-iLcqBr_n_F5gNrzQbBMrKgkpGwqTu7boWeoYepf%3D%2B8g%40mail.gmail.com

Thanks for the information.

> I've already spent some time looking at it and I think it's more advanced than
> the previous attempts to implement the "unique keys".

So do I. Therefore I'll switch current commitfest into "Withdrawn". I'll
take a look Richard's patch too.

--
Best regards,
Ilia Evdokimov,
Tantor Labs LLC,
https://tantorlabs.com/

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