Re: Introduce XID age and inactive timeout based replication slot invalidation

On Tue, Mar 19, 2024 at 3:11 PM Bertrand Drouvot
<bertranddrouvot(dot)pg(at)gmail(dot)com> wrote:
>
> On Tue, Mar 19, 2024 at 10:56:25AM +0530, Amit Kapila wrote:
> > On Mon, Mar 18, 2024 at 8:19 PM Bertrand Drouvot
> > <bertranddrouvot(dot)pg(at)gmail(dot)com> wrote:
> > > Agree. While it makes sense to invalidate slots for wal removal in
> > > CreateCheckPoint() (because this is the place where wal is removed), I 'm not
> > > sure this is the right place for the 2 new cases.
> > >
> > > Let's focus on the timeout one as proposed above (as probably the simplest one):
> > > as this one is purely related to time and activity what about to invalidate them
> > > when?:
> > >
> > > - their usage resume
> > > - in pg_get_replication_slots()
> > >
> > > The idea is to invalidate the slot when one resumes activity on it or wants to
> > > get information about it (and among other things wants to know if the slot is
> > > valid or not).
> > >
> >
> > Trying to invalidate at those two places makes sense to me but we
> > still need to cover the cases where it takes very long to resume the
> > slot activity and the dangling slot cases where the activity is never
> > resumed.
>
> I understand it's better to have the slot reflecting its real status internally
> but it is a real issue if that's not the case until the activity on it is resumed?
> (just asking, not saying we should not)
>

Sorry, I didn't understand your point. Can you try to explain by example?

--
With Regards,
Amit Kapila.