Re: Should vacuum process config file reload more often

Hi,

On 2023-02-27 23:11:53 +0900, Masahiko Sawada wrote:
> As far as I know there are not such GUC parameters in the core but
> there might be in third-party table AM and index AM extensions.

We already reload in a pretty broad range of situations, so I'm not sure
there's a lot that could be unsafe that isn't already.

> Also, I'm concerned that allowing to change any GUC parameters during
> vacuum/analyze could be a foot-gun in the future. When modifying
> vacuum/analyze-related codes, we have to consider the case where any GUC
> parameters could be changed during vacuum/analyze.

What kind of scenario are you thinking of?

> I guess it would be better to apply the parameter changes for only vacuum
> delay related parameters. For example, autovacuum launcher advertises the
> values of the vacuum delay parameters on the shared memory not only for
> autovacuum processes but also for manual vacuum/analyze processes. Both
> processes can update them accordingly in vacuum_delay_point().

I don't think this is a good idea. It'd introduce a fair amount of complexity
without, as far as I can tell, a benefit.

Greetings,

Andres Freund