Re: Partial hash index is not used for implied qual.

From: Sergei Glukhov <s(dot)glukhov(at)postgrespro(dot)ru>
To: David Rowley <dgrowleyml(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: Partial hash index is not used for implied qual.
Date: 2025-11-27 08:39:34
Message-ID: 7009dd30-5d4e-49a2-af1d-c1b5f8e02288@postgrespro.ru
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Hi,

On 11/27/25 7:01 AM, David Rowley wrote:
> On Thu, 27 Nov 2025 at 07:26, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> So I'm inclined to apply the attached and just call it good.
> I think the patch looks fine.

+1, verified, thanks a lot!

>
>> Should we back-patch? I'm unsure. Clearly it's a bug that we
>> cannot generate an indexscan plan in this case, but we've learned
>> that changing plans in released branches is often not wanted.
>> And given the lack of field complaints, nobody is using the case
>> anyway.
> I feel like anyone adding a partial hash index has done so quite
> purposefully. I suspect they might be surprised if there's no means
> whatsoever to use that index in scans, so perhaps it's ok to
> backpatch.
>
> Sergei, can you confirm if this was something he noticed when playing
> around on master, or if this came from a field report?

It was reported for v16.

Regards,
Sergei Glukhov

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