Re: Introduce XID age and inactive timeout based replication slot invalidation
Amit Kapila <amit.kapila16@gmail.com>
Commits
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 Fri, Mar 22, 2024 at 5:30 PM Bertrand Drouvot
<bertranddrouvot.pg@gmail.com> wrote:
>
> On Fri, Mar 22, 2024 at 03:56:23PM +0530, Amit Kapila wrote:
> > On Fri, Mar 22, 2024 at 3:15 PM Bertrand Drouvot
> > <bertranddrouvot.pg@gmail.com> wrote:
> > >
> > > On Fri, Mar 22, 2024 at 01:45:01PM +0530, Bharath Rupireddy wrote:
> > >
> > > 1 ===
> > >
> > > @@ -691,6 +699,13 @@ ReplicationSlotRelease(void)
> > > ConditionVariableBroadcast(&slot->active_cv);
> > > }
> > >
> > > + if (slot->data.persistency == RS_PERSISTENT)
> > > + {
> > > + SpinLockAcquire(&slot->mutex);
> > > + slot->last_inactive_at = GetCurrentTimestamp();
> > > + SpinLockRelease(&slot->mutex);
> > > + }
> > >
> > > I'm not sure we should do system calls while we're holding a spinlock.
> > > Assign a variable before?
> > >
> > > 2 ===
> > >
> > > Also, what about moving this here?
> > >
> > > "
> > > if (slot->data.persistency == RS_PERSISTENT)
> > > {
> > > /*
> > > * Mark persistent slot inactive. We're not freeing it, just
> > > * disconnecting, but wake up others that may be waiting for it.
> > > */
> > > SpinLockAcquire(&slot->mutex);
> > > slot->active_pid = 0;
> > > SpinLockRelease(&slot->mutex);
> > > ConditionVariableBroadcast(&slot->active_cv);
> > > }
> > > "
> > >
> > > That would avoid testing twice "slot->data.persistency == RS_PERSISTENT".
> > >
> >
> > That sounds like a good idea. Also, don't we need to consider physical
> > slots where we don't reserve WAL during slot creation? I don't think
> > there is a need to set inactive_at for such slots.
>
> If the slot is not active, why shouldn't we set inactive_at? I can understand
> that such a slots do not present "any risks" but I think we should still set
> inactive_at (also to not give the false impression that the slot is active).
>
But OTOH, there is a chance that we will invalidate such slots even
though they have never reserved WAL in the first place which doesn't
appear to be a good thing.
> > > 5 ===
> > >
> > > Most of the fields that reflect a time (not duration) in the system views are
> > > xxxx_time, so I'm wondering if instead of "last_inactive_at" we should use
> > > something like "last_inactive_time"?
> > >
> >
> > How about naming it as last_active_time? This will indicate the time
> > at which the slot was last active.
>
> I thought about it too but I think it could be missleading as one could think that
> it should be updated each time WAL record decoding is happening.
>
Fair enough.
--
With Regards,
Amit Kapila.