Re: maintenance_work_mem = 64kB doesn't work for vacuum

David Rowley <dgrowleyml@gmail.com>

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From: David Rowley <dgrowleyml@gmail.com>

To: Masahiko Sawada <sawada.mshk@gmail.com>

Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>

Date: 2025-03-10T02:03:24Z

Lists: pgsql-hackers

Attachments

ensure_weve_at_least_one_page_before_vacuum_index_cleanup.patch (application/octet-stream) patch

On Mon, 10 Mar 2025 at 10:30, David Rowley <dgrowleyml@gmail.com> wrote:
> Could you do something similar to what's in hash_agg_check_limits()
> where we check we've got at least 1 item before bailing before we've
> used up the all the prescribed memory?  That seems like a safer coding
> practise as if in the future the minimum usage for a DSM segment goes
> above 256KB, the bug comes back again.

FWIW, I had something like the attached in mind.

David

Commits

Fix assertion failure in parallel vacuum with minimal maintenance_work_mem setting.
- f4290f20dd4d 18.0 landed
- a38dce3c4a90 17.5 landed
Lower minimum maintenance_work_mem to 64kB
- bbf668d66fbf 18.0 cited