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

Ajin Cherian <itsajin@gmail.com>

From: Ajin Cherian <itsajin@gmail.com>

To: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>

Cc: Amit Kapila <amit.kapila16@gmail.com>, Bertrand Drouvot <bertranddrouvot.pg@gmail.com>, shveta malik <shveta.malik@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, Nathan Bossart <nathandbossart@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>

Date: 2024-08-14T03:50:38Z

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 Mon, Jun 24, 2024 at 4:01 PM Bharath Rupireddy <
bharath.rupireddyforpostgres@gmail.com> wrote:

> Hi,
>
> On Mon, Jun 17, 2024 at 5:55 PM Bharath Rupireddy
> <bharath.rupireddyforpostgres@gmail.com> wrote:
>
> Please find the attached v41 patches implementing the idea of vacuum
> doing the invalidation.
>
> Thoughts?
>
>
>

Some minor comments on the patch:
1.
+ /*
+ * Release the lock if it's not yet to keep the cleanup path on
+ * error happy.
+ */

I suggest rephrasing to: " "Release the lock if it hasn't been already to
ensure smooth cleanup on error."


2.

elog(DEBUG1, "performing replication slot invalidation");

Probably change it to "performing replication slot invalidation checks" as
we might not actually invalidate any slot here.

3.

In CheckPointReplicationSlots()

+ invalidated =
InvalidateObsoleteReplicationSlots(RS_INVAL_INACTIVE_TIMEOUT,
+ 0,
+ InvalidOid,
+ InvalidTransactionId);
+
+ if (invalidated)
+ {
+ /*
+ * If any slots have been invalidated, recalculate the resource
+ * limits.
+ */
+ ReplicationSlotsComputeRequiredXmin(false);
+ ReplicationSlotsComputeRequiredLSN();
+ }

Is this calculation of resource limits really required here when the same
is already done inside InvalidateObsoleteReplicationSlots()


regards,
Ajin Cherian
Fujitsu Australia