Horton

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

Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

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From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: shveta malik <shveta.malik@gmail.com>, Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, Nathan Bossart <nathandbossart@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-03-25T08:07:35Z
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 →

  1. Add a test for commit ac0e33136a using the injection point.

  2. Invalidate inactive replication slots.

  3. Fix incorrect slot type in BuildTupleHashTableExt

  4. Allow synced slots to have their inactive_since.

  5. Change last_inactive_time to inactive_since in pg_replication_slots.

  6. Track last_inactive_time in pg_replication_slots.

  7. Track invalidation_reason in pg_replication_slots.

  8. Add option force_initdb to PostgreSQL::Test::Cluster:init()

  9. Add a failover option to subscriptions.

  10. Allow setting failover property in the replication command.

  11. Allow to enable failover property for replication slots via SQL API.

  12. Track conflict_reason in pg_replication_slots.

  13. Log messages for replication slot acquisition and release.

  14. Remove vacuum_defer_cleanup_age

  15. Fix corruption due to vacuum_defer_cleanup_age underflowing 64bit xids

  16. meson: Add initial version of meson based build system

Hi,

On Mon, Mar 25, 2024 at 12:59:52PM +0530, Amit Kapila wrote:
> On Mon, Mar 25, 2024 at 12:43 PM shveta malik <shveta.malik@gmail.com> wrote:
> >
> > On Mon, Mar 25, 2024 at 11:53 AM shveta malik <shveta.malik@gmail.com> wrote:
> > >
> > > On Mon, Mar 25, 2024 at 10:33 AM shveta malik <shveta.malik@gmail.com> wrote:
> > > >
> > > > On Sun, Mar 24, 2024 at 3:06 PM Bharath Rupireddy
> > > > <bharath.rupireddyforpostgres@gmail.com> wrote:
> > > > >
> > > > > I've attached the v18 patch set here.
> >
> > I have one concern, for synced slots on standby, how do we disallow
> > invalidation due to inactive-timeout immediately after promotion?
> >
> > For synced slots, last_inactive_time and inactive_timeout are both
> > set.

Yeah, and I can see last_inactive_time is moving on the standby (while not the
case on the primary), probably due to the sync worker slot acquisition/release
which does not seem right.

> Let's say I bring down primary for promotion of standby and then
> > promote standby, there are chances that it may end up invalidating
> > synced slots (considering standby is not brought down during promotion
> > and thus inactive_timeout may already be past 'last_inactive_time').
> >
> 
> This raises the question of whether we need to set
> 'last_inactive_time' synced slots on the standby?

Yeah, I think that last_inactive_time should stay at 0 on synced slots on the
standby because such slots are not usable anyway (until the standby gets promoted).

So, I think that last_inactive_time does not make sense if the slot never had
the chance to be active.

OTOH I think the timeout invalidation (if any) should be synced from primary.

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com