Re: allow changing autovacuum_max_workers without restarting

On Mon, Jan 06, 2025 at 03:50:24PM -0600, Nathan Bossart wrote:
> I'm obviously biased, but I think it would be unfortunate to block features
> like this one because of low settings that would otherwise be unsuitable
> for any reasonable production workload. If we do want to at least support
> check-world on these systems, another option could be to simply lower the
> default of autovacuum_worker_slots to 7 (or maybe lower). Of course, that
> only helps until the next time more semaphores are required, but that's not
> a new problem.

I've attached a patch to lower the default to 5. That at least gives a
little bit of wiggle room for autovacuum_max_workers (and for a couple of
new auxiliary processes). FWIW the reason I originally set the default to
16 was to prevent most users from ever needing to think about adjusting
autovacuum_worker_slots (which requires a restart and is a completely new
parameter that most will be unfamiliar with).

--
nathan