Horton

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

Nisha Moond <nisha.moond412@gmail.com>

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From: Nisha Moond <nisha.moond412@gmail.com>
To: vignesh C <vignesh21@gmail.com>
Cc: Peter Smith <smithpb2250@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, shveta malik <shveta.malik@gmail.com>, Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, Ajin Cherian <itsajin@gmail.com>, Bertrand Drouvot <bertranddrouvot.pg@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, Nathan Bossart <nathandbossart@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-01-16T07:07:18Z
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 Mon, Jan 13, 2025 at 12:22 PM vignesh C <vignesh21@gmail.com> wrote:
>
> On Thu, 2 Jan 2025 at 15:57, Nisha Moond <nisha.moond412@gmail.com> wrote:
> >
> > Thank you for your feedback! Please find the v59 patch set addressing
> > all the comments.
> > Note: There are no new changes in patch-0001.
>
> Few comments:
> 1) I felt we should not invalidate the slots for which has no
> effective xmin set as they will not be holding the WAL files from
> deletion. This can happen when user created slots with
> immediately_reserve as false and lsn will be actually reserved only
> after the first connection from a streaming replication client:
> +static inline bool
> +CanInvalidateIdleSlot(ReplicationSlot *s)
> +{
> +       return (idle_replication_slot_timeout_mins > 0 &&
> +                       s->inactive_since > 0 &&
> +                       !(RecoveryInProgress() && s->data.synced));
> +}
>

IIUC, for both logical and physical replication slots, the effective
xmin remains NULL until the respective nodes establish their first
connection. However, logical slots always reserve WAL immediately,
whereas physical slots do not unless immediately_reserve=true is set.
To avoid unnecessary slot invalidation for slots that are not
reserving WAL when created, it might be better to check the
restart_lsn instead of effective_xmin. If restart_lsn is invalid for a
slot, it indicates that WAL is not reserved for the slot, and we can
safely skip invalidation due to idle_timeout for such slots. This
logic has been implemented in v60.

--
Thanks,
Nisha