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

Amit Kapila <amit.kapila16@gmail.com>

From: Amit Kapila <amit.kapila16@gmail.com>

To: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

Cc: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, shveta malik <shveta.malik@gmail.com>, Nathan Bossart <nathandbossart@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>

Date: 2024-03-26T08:07:21Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Add a test for commit ac0e33136a using the injection point.
- 8a695d7998be 18.0 landed
Invalidate inactive replication slots.
- ac0e33136abc 18.0 landed
Fix incorrect slot type in BuildTupleHashTableExt
- d96d1d5152f3 18.0 cited
Allow synced slots to have their inactive_since.
- 6f132ed693b6 17.0 landed
Change last_inactive_time to inactive_since in pg_replication_slots.
- 6d49c8d4b4f4 17.0 landed
Track last_inactive_time in pg_replication_slots.
- a11f330b5584 17.0 landed
Track invalidation_reason in pg_replication_slots.
- 6ae701b4378d 17.0 landed
Add option force_initdb to PostgreSQL::Test::Cluster:init()
- ff9e1e764fcc 17.0 cited
Add a failover option to subscriptions.
- 776621a5e479 17.0 cited
Allow setting failover property in the replication command.
- 73292404370c 17.0 cited
Allow to enable failover property for replication slots via SQL API.
- c393308b69d2 17.0 cited
Track conflict_reason in pg_replication_slots.
- 007693f2a3ac 17.0 cited
Log messages for replication slot acquisition and release.
- 7c3fb505b14e 17.0 cited
Remove vacuum_defer_cleanup_age
- 1118cd37eb61 16.0 cited
Fix corruption due to vacuum_defer_cleanup_age underflowing 64bit xids
- be504a3e974d 16.0 cited
meson: Add initial version of meson based build system
- e6927270cd18 16.0 cited

On Tue, Mar 26, 2024 at 1:15 PM Bertrand Drouvot
<bertranddrouvot.pg@gmail.com> wrote:
>
> 2 ===
>
> It looks like inactive_since is set to the current timestamp on the standby
> each time the sync worker does a cycle:
>
> primary:
>
> postgres=# select slot_name,inactive_since from pg_replication_slots where failover = 't';
>   slot_name  |        inactive_since
> -------------+-------------------------------
>  lsub27_slot | 2024-03-26 07:39:19.745517+00
>  lsub28_slot | 2024-03-26 07:40:24.953826+00
>
> standby:
>
> postgres=# select slot_name,inactive_since from pg_replication_slots where failover = 't';
>   slot_name  |        inactive_since
> -------------+-------------------------------
>  lsub27_slot | 2024-03-26 07:43:56.387324+00
>  lsub28_slot | 2024-03-26 07:43:56.387338+00
>
> I don't think that should be the case.
>

But why? This is exactly what we discussed in another thread where we
agreed to update inactive_since even for sync slots. In each sync
cycle, we acquire/release the slot, so the inactive_since gets
updated. See synchronize_one_slot().

-- 
With Regards,
Amit Kapila.