Re: BUG #17973: Reinit of pgstats entry for dropped DB can break autovacuum daemon

On Thu, Jun 15, 2023 at 6:01 PM Michael Paquier <michael@paquier.xyz> wrote:
> It requires a few manual steps, but I have been able to stuck the
> autovacuum launcher schedule.  Nice investigation from the reporters.
>
> I may be missing something here, but finishing with an inconsistent
> database list (generated based on the pgstat database entries) in the
> autovacuum launcher is not something that can happen only because of a
> worker, right?  A normal backend would call pgstat_update_dbstats()
> once it exists, re-creating a fresh entry with the dropped database
> OID.  Is that right?

Yes, sorry, Jacob was able to repro with a normal backend just now. We
probably should have tried that earlier. :-)

I'm also unsure if reiniting the pgstats entry (as opposed to creating
a new one) is actually necessary or just what we happened to observe.
We're definitely not very familiar with these internals. :-)