Re: allow changing autovacuum_max_workers without restarting

On Mon, Jul 08, 2024 at 02:29:16PM -0500, Nathan Bossart wrote:
> One thing that still bugs me is that there is no feedback sent to the user
> when autovacuum_max_workers is set higher than autovacuum_worker_slots. I
> think we should at least emit a WARNING, perhaps from the autovacuum
> launcher, i.e., once when the launcher starts and then again as needed via
> HandleAutoVacLauncherInterrupts(). Or we could fail to start in
> PostmasterMain() and then ignore later misconfigurations via a GUC check
> hook. I'm not too thrilled about adding more GUC check hooks that depend
> on the value of other GUCs, but I do like the idea of failing instead of
> silently proceeding with a different value than the user configured. Any
> thoughts?

From recent discussions, it sounds like there isn't much appetite for GUC
check hooks that depend on the values of other GUCs. Here is a new version
of the patch that adds the WARNING described above.

--
nathan