Re: Should vacuum process config file reload more often

On Thu, Mar 2, 2023 at 5:45 AM Andres Freund <andres(at)anarazel(dot)de> wrote:
>
> On 2023-02-28 11:16:45 +0900, Masahiko Sawada wrote:
> > On Tue, Feb 28, 2023 at 10:21 AM Andres Freund <andres(at)anarazel(dot)de> wrote:
> > > 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?
> >
> > For example, I guess we will need to take care of changes of
> > maintenance_work_mem. Currently we initialize the dead tuple space at
> > the beginning of lazy vacuum, but perhaps we would need to
> > enlarge/shrink it based on the new value?
>
> I don't think we need to do anything about that initially, just because the
> config can be changed in a more granular way, doesn't mean we have to react to
> every change for the current operation.
>

+1. I also don't see the need to do anything for this case.

--
With Regards,
Amit Kapila.