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

On 2026-Jul-09, Heikki Linnakangas 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.

Because it scans pg_database.

commit 00e6a16d01683762c2f34eb4909fc739093ab3bf
Author: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> []
AuthorDate: Mon Aug 31 19:41:00 2009 +0000
CommitDate: Mon Aug 31 19:41:00 2009 +0000

Change the autovacuum launcher to read pg_database directly, rather than
via the "flat files" facility. This requires making it enough like a backend
to be able to run transactions; it's no longer an "auxiliary process" but
more like the autovacuum worker processes. Also, its signal handling has
to be brought into line with backends/workers. In particular, since it
now has to handle procsignal.c processing, the special autovac-launcher-only
signal conditions are moved to SIGUSR2.

Alvaro, with some cleanup from Tom

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