Re: pgsql: Refactor how some aux processes advertise their ProcNumber

From: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
To: Heikki Linnakangas <hlinnaka(at)iki(dot)fi>
Cc: Thom Brown <thom(at)linux(dot)com>, pgsql-committers(at)lists(dot)postgresql(dot)org
Subject: Re: pgsql: Refactor how some aux processes advertise their ProcNumber
Date: 2026-07-09 12:34:50
Message-ID: CAHGQGwEwLCGpRnKOnxBz-a5zPUdEdBPhGrq7GPgxc3KtDpyHoQ@mail.gmail.com
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On Thu, Jul 9, 2026 at 9:17 PM Heikki Linnakangas <hlinnaka(at)iki(dot)fi> wrote:
> Why is the autovacuum launcher not an aux process? I guess it's because
> it needs to acquire a heavy-weight lock in order to read the list of
> databases.

That seems to be one of the reasons, based on the comment about auxiliary
processes in miscadmin.h:

-------------------------
* Auxiliary processes. These have PGPROC entries, but they are not
* attached to any particular database, and cannot run transactions or
* even take heavyweight locks. There can be only one of each of these
* running at a time, except for IO workers.
-------------------------

Regards,

--
Fujii Masao

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