Horton

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

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Cc: Nathan Bossart <nathandbossart@gmail.com>, Bertrand Drouvot <bertranddrouvot.pg@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-03-11T05:55:57Z
Lists: pgsql-hackers

Commits

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  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

On Fri, Mar 8, 2024 at 8:08 PM Bharath Rupireddy
<bharath.rupireddyforpostgres@gmail.com> wrote:
>
> On Wed, Mar 6, 2024 at 4:28 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > IIUC, the current conflict_reason is primarily used to determine
> > logical slots on standby that got invalidated due to recovery time
> > conflict. On the primary, it will also show logical slots that got
> > invalidated due to the corresponding WAL got removed. Is that
> > understanding correct?
>
> That's right.
>
> > If so, we are already sort of overloading this
> > column. However, now adding more invalidation reasons that won't
> > happen during recovery conflict handling will change entirely the
> > purpose (as per the name we use) of this variable. I think
> > invalidation_reason could depict this column correctly but OTOH I
> > guess it would lose its original meaning/purpose.
>
> Hm. I get the concern. Are you okay with having inavlidation_reason
> separately for both logical and physical slots? In such a case,
> logical slots that got invalidated on the standby will have duplicate
> info in conflict_reason and invalidation_reason, is this fine?
>

If we have duplicate information in two columns that could be
confusing for users. BTW, isn't the recovery conflict occur only
because of rows_removed and wal_level_insufficient reasons? The
wal_removed or the new reasons you are proposing can't happen because
of recovery conflict. Am, I missing something here?

> Another idea is to make 'conflict_reason text' as a 'conflicting
> boolean' again (revert 007693f2a3), and have 'invalidation_reason
> text' for both logical and physical slots. So, whenever 'conflicting'
> is true, one can look at invalidation_reason for the reason for
> conflict. How does this sound?
>

So, does this mean that conflicting will only be true for some of the
reasons (say wal_level_insufficient, rows_removed, wal_removed) and
logical slots but not for others? I think that will also not eliminate
the duplicate information as user could have deduced that from single
column

-- 
With Regards,
Amit Kapila.