Re: maintenance_work_mem = 64kB doesn't work for vacuum - Mailing list pgsql-hackers

From David Rowley
Subject Re: maintenance_work_mem = 64kB doesn't work for vacuum
Date
Msg-id CAApHDvo8fb9MkfH7VPwg80=hjq64=ps6NaQ8SjoB7soYL-=iZg@mail.gmail.com
Whole thread Raw
In response to maintenance_work_mem = 64kB doesn't work for vacuum  (Masahiko Sawada <sawada.mshk@gmail.com>)
Responses Re: maintenance_work_mem = 64kB doesn't work for vacuum
List pgsql-hackers
On Mon, 10 Mar 2025 at 07:46, Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> A simple fix is to bump the minimum maintenance_work_mem to 256kB. We
> would break the compatibility for backbranch (i.e. v17) but I guess
> it's unlikely that existing v17 users are using less than 1MB
> maintenance_work_mem (the release note doesn't mention the fact that
> we lowered the minimum value).

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.

David



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