Re: Introduce XID age and inactive timeout based replication slot invalidation - Mailing list pgsql-hackers

On Tue, Sep 3, 2024 at 3:01 PM shveta malik <shveta.malik@gmail.com> wrote:
>
>
> 1)
> I see that ReplicationSlotAlter() will error out if the slot is
> invalidated due to timeout. I have not tested it myself, but do you
> know if  slot-alter errors out for other invalidation causes as well?
> Just wanted to confirm that the behaviour is consistent for all
> invalidation causes.

I was able to test this and as anticipated behavior is different. When
slot is invalidated due to say 'wal_removed', I am still able to do
'alter' of that slot.
Please see:

Pub:
  slot_name  | failover | synced |          inactive_since          |
invalidation_reason
-------------+----------+--------+----------------------------------+---------------------
 mysubnew1_1 | t        | f      | 2024-09-04 08:58:12.802278+05:30 |
wal_removed

Sub:
newdb1=# alter subscription mysubnew1_1 disable;
ALTER SUBSCRIPTION

newdb1=# alter subscription mysubnew1_1 set (failover=false);
ALTER SUBSCRIPTION

Pub: (failover altered)
  slot_name  | failover | synced |          inactive_since          |
invalidation_reason
-------------+----------+--------+----------------------------------+---------------------
 mysubnew1_1 | f        | f      | 2024-09-04 08:58:47.824471+05:30 |
wal_removed


while when invalidation_reason is 'inactive_timeout', it fails:

Pub:
  slot_name  | failover | synced |          inactive_since          |
invalidation_reason
-------------+----------+--------+----------------------------------+---------------------
 mysubnew1_1 | t        | f      | 2024-09-03 14:30:57.532206+05:30 |
inactive_timeout

Sub:
newdb1=# alter subscription mysubnew1_1 disable;
ALTER SUBSCRIPTION

newdb1=# alter subscription mysubnew1_1 set (failover=false);
ERROR:  could not alter replication slot "mysubnew1_1": ERROR:  can no
longer get changes from replication slot "mysubnew1_1"
DETAIL:  The slot became invalid because it was inactive since
2024-09-04 08:54:20.308996+05:30, which is more than 0 seconds ago.
HINT:  You might need to increase "replication_slot_inactive_timeout.".

I think the behavior should be same.

thanks
Shveta