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

On Tue, Mar 12, 2024 at 10:10 PM Bharath Rupireddy
<bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:
>
> On Mon, Mar 11, 2024 at 3:44 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> >
> > Yes, your understanding is correct. I wanted us to consider having new
> > parameters like 'inactive_replication_slot_timeout' to be at
> > slot-level instead of GUC. I think this new parameter doesn't seem to
> > be the similar as 'max_slot_wal_keep_size' which leads to truncation
> > of WAL at global and then invalidates the appropriate slots. OTOH, the
> > 'inactive_replication_slot_timeout' doesn't appear to have a similar
> > global effect.
>
> last_inactive_at is tracked for each slot using which slots get
> invalidated based on inactive_replication_slot_timeout. It's like
> max_slot_wal_keep_size invalidating slots based on restart_lsn. In a
> way, both are similar, right?
>

There is some similarity but 'max_slot_wal_keep_size' leads to
truncation of WAL which in turn leads to invalidation of slots. Here,
I am also trying to be cautious in adding a GUC unless it is required
or having a slot-level parameter doesn't serve the need. Having said
that, I see that there is an argument that we should follow the path
of 'max_slot_wal_keep_size' GUC and there is some value to it but
still I think avoiding a new GUC for inactivity in the slot would
outweigh.

--
With Regards,
Amit Kapila.