Horton

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

Alvaro Herrera <alvherre@alvh.no-ip.org>

View thread
From: Álvaro Herrera <alvherre@alvh.no-ip.org>
To: Nisha Moond <nisha.moond412@gmail.com>
Cc: Peter Smith <smithpb2250@gmail.com>, vignesh C <vignesh21@gmail.com>, "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>, Amit Kapila <amit.kapila16@gmail.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: 2025-02-11T14:22:49Z
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

Hello,

I find this proposed patch a bit strange and I feel it needs more
explanation.

When this thread started, Bharath justified his patches saying that a
slot that's inactive for a very long time could be problematic because
of XID wraparound.  Fine, that sounds a reasonable feature.  If you
wanted to invalidate slots whose xmins were too old, I would support
that.  He submitted that as his 0004 patch then.

However, he also chose to submit 0003 with invalidation based on a
timeout.  This is far less convincing a feature to me.  The
justification for the time out seems to be that ... it's difficult to
have a one-size-fits-all value because size of disks vary. (???)
Or something like that.  Really?  I mean -- yes, this will prevent
problems in toy databases when run in developer's laptops.  It will not
prevent any problems in production databases.  Do we really want a
setting that is only useful for toy situations rather than production?


Anyway, the thread is way too long, but after some initial pieces were
committed, Nisha took over and submitting patches derived from Bharath's
0003, and at some point the initial 0004 was dropped.  But 0004 was the
more useful one, I thought, so what's going on?

I'm baffled.

-- 
Álvaro Herrera         PostgreSQL Developer  —  https://www.EnterpriseDB.com/
Officer Krupke, what are we to do?
Gee, officer Krupke, Krup you! (West Side Story, "Gee, Officer Krupke")