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

Amit Kapila <amit.kapila16@gmail.com>

From: Amit Kapila <amit.kapila16@gmail.com>

To: Peter Smith <smithpb2250@gmail.com>

Cc: Nisha Moond <nisha.moond412@gmail.com>, vignesh C <vignesh21@gmail.com>, "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>, Shlok Kyal <shlok.kyal.oss@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: 2025-02-11T06:17:34Z

Lists: pgsql-hackers

Commits

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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 Tue, Feb 11, 2025 at 8:49 AM Peter Smith <smithpb2250@gmail.com> wrote:
>
>
> InvalidatePossiblyObsoleteSlot:
>
> 2.
> + if (possible_causes & RS_INVAL_IDLE_TIMEOUT)
> + {
> + /*
> + * Assign the current time here to avoid system call overhead
> + * while holding the spinlock in subsequent code.
> + */
> + now = GetCurrentTimestamp();
> + }
> +
>
> I felt that any minuscule benefit gained from having this conditional
> 'now' assignment is outweighed by the subsequent confusion/doubt
> caused by passing around a 'now' to other functions where it may or
> may not still be zero depending on different processing. IMO we should
> just remove all doubts and always assign it so that "now always means
> now".
>

I think we shouldn't pass now to another function, but rather do all
required computations in the caller (probably in a separate inline
function). And keep the above code as is.

-- 
With Regards,
Amit Kapila.