Re: Lowering temp_buffers minimum

From: Andres Freund <andres(at)anarazel(dot)de>
To: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Lowering temp_buffers minimum
Date: 2025-02-26 09:53:12
Message-ID: knr4aazlaa4nj3xnpe4tu6plwayovzxhmteatcpry2j6a6kc4v@aonkl53s2ecs
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Hi,

On 2025-02-25 09:33:36 -0500, Andres Freund wrote:
> I am working on writing some tests for temporary tables. One of the tests is
> that we correctly handle running out of buffer pins. That's a bit more
> annoying than it needs to because the minimum for temp_buffers is 100.
>
> It seems rather odd that our minimum for temp_buffers is 100 while the minimum
> for shared_buffers, which is shared across connections!, is 16.
>
> Does anybody see a reason we shouldn't lower temp_buffers to match
> shared_buffers?

FWIW, here's a set of patches adding some testing for temp table corner cases
that aren't currently hit, even in master. They work with temp_buffers = 100,
but would require a smaller table if a lower minimum . And indeed the test
would currently fail without the preceding commits I included, which are from

https://www.postgresql.org/message-id/CA%2BhUKGK_%3D4CVmMHvsHjOVrK6t4F%3DLBpFzsrr3R%2BaJYN8kcTfWg%40mail.gmail.com

Greetings,

Andres Freund

Attachment Content-Type Size
v1-0001-Improve-buffer-pool-API-for-per-backend-pin-limit.patch text/x-diff 6.5 KB
v1-0002-Respect-pin-limits-accurately-in-read_stream.c.patch text/x-diff 10.0 KB
v1-0003-WIP-tests-Expand-temp-table-tests-to-some-pin-rel.patch text/x-diff 9.6 KB

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