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

Hi,

On Mon, Mar 18, 2024 at 08:50:56AM +0530, Amit Kapila wrote:
> On Sun, Mar 17, 2024 at 2:03 PM Bharath Rupireddy
> <bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:
> >
> > On Sat, Mar 16, 2024 at 3:55 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> > >
> > > procArray->replication_slot_catalog_xmin) but then don't adjust it for
> > > 'max_slot_xid_age'. I could be missing something in this but it is
> > > better to keep discussing this and try to move with another parameter
> > > 'inactive_replication_slot_timeout' which according to me can be kept
> > > at slot level instead of a GUC but OTOH we need to see the arguments
> > > on both side and then decide which makes more sense.
> >
> > Hm. Are you suggesting inactive_timeout to be a slot level parameter
> > similar to 'failover' property added recently by
> > c393308b69d229b664391ac583b9e07418d411b6 and
> > 73292404370c9900a96e2bebdc7144f7010339cf? With this approach, one can
> > set inactive_timeout while creating the slot either via
> > pg_create_physical_replication_slot() or
> > pg_create_logical_replication_slot() or CREATE_REPLICATION_SLOT or
> > ALTER_REPLICATION_SLOT command, and postgres tracks the
> > last_inactive_at for every slot based on which the slot gets
> > invalidated. If this understanding is right, I can go ahead and work
> > towards it.
> >
>
> Yeah, I have something like that in mind. You can prepare the patch
> but it would be good if others involved in this thread can also share
> their opinion.

I think it makes sense to put the inactive_timeout granularity at the slot
level (as the activity could vary a lot say between one slot linked to a
subcription and one linked to some plugins). As far max_slot_xid_age I've the
feeling that a new GUC is good enough.

> > Alternatively, we can go the route of making GUC a list of key-value
> > pairs of {slot_name, inactive_timeout}, but this kind of GUC for
> > setting slot level parameters is going to be the first of its kind, so
> > I'd prefer the above approach.
> >
>
> I would prefer a slot-level parameter in this case rather than a GUC.

Yeah, same here.

Regards,

--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com