Horton

Re: Synchronizing slots from primary to standby

shveta malik <shveta.malik@gmail.com>

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From: shveta malik <shveta.malik@gmail.com>
To: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>, Dilip Kumar <dilipbalaut@gmail.com>, Peter Smith <smithpb2250@gmail.com>, Nisha Moond <nisha.moond412@gmail.com>, "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>, Bruce Momjian <bruce@momjian.us>, Ashutosh Sharma <ashu.coek88@gmail.com>, Andres Freund <andres@anarazel.de>, pgsql-hackers <pgsql-hackers@postgresql.org>, Ajin Cherian <itsajin@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>, shveta malik <shveta.malik@gmail.com>
Date: 2024-01-24T10:39:15Z
Lists: pgsql-hackers 
On Wed, Jan 24, 2024 at 2:38 PM Bertrand Drouvot
<bertranddrouvot.pg@gmail.com> wrote:
>
> Hi,
>
> On Wed, Jan 24, 2024 at 01:51:54PM +0530, Amit Kapila wrote:
> > On Wed, Jan 24, 2024 at 11:24 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> > >
> > > On Wed, Jan 24, 2024 at 2:43 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> > > >
> > > > >
> > > > > +/* GUC variable */
> > > > > +bool       enable_syncslot = false;
> > > > >
> > > > > Is enable_syncslot a really good name? We use "enable" prefix only for
> > > > > planner parameters such as enable_seqscan, and it seems to me that
> > > > > "slot" is not specific. Other candidates are:
> > > > >
> > > > > * synchronize_replication_slots = on|off
> > > > > * synchronize_failover_slots = on|off
> > > > >
> > > >
> > > > I would prefer the second one. Would it be better to just say
> > > > sync_failover_slots?
> > >
> > > Works for me. But if we want to extend this option for non-failover
> > > slots as well in the future, synchronize_replication_slots (or
> > > sync_replication_slots) seems better. We can extend it by having an
> > > enum later. For example, the values can be on, off, or failover etc.
> > >
> >
> > I see your point. Let us see if others have any suggestions on this.
>
> I also see Sawada-San's point and I'd vote for "sync_replication_slots". Then for
> the current feature I think "failover" and "on" should be the values to turn the
> feature on (assuming "on" would mean "all kind of supported slots").

Even if others agree and we change this GUC name to
"sync_replication_slots", I feel we should keep the values as "on" and
"off" currently, where "on" would mean 'sync failover slots' (docs can
state that clearly).  I do not think we should support sync of "all
kinds of supported slots" in the first version. Maybe we can think
about it for future versions.

thanks
Shveta

Commits

  1. Doc: Add the new section "Logical Replication Failover".

  2. Fix the review comments and a bug in the slot sync code.

  3. Fix a test in failover slots regression test.

  4. Fix the intermittent buildfarm failures in 040_standby_failover_slots_sync.

  5. Split XLogCtl->LogwrtResult into separate struct members

  6. Ensure that the sync slots reach a consistent state after promotion without losing data.

  7. Introduce a new GUC 'standby_slot_names'.

  8. Fix BF failure introduced by commit b3f6b14cf4.

  9. Fixups for commit 93db6cbda0.

  10. Fix BF failure in commit 93db6cbda0.

  11. Add a new slot sync worker to synchronize logical slots.

  12. Improve ERROR/LOG messages added by commits ddd5f4f54a and 7a424ece48.

  13. Disable autovacuum on primary in 040_standby_failover_slots_sync test.

  14. Fix the incorrect format specifier used in commit 7a424ece48.

  15. Change the LOG level in 040_standby_failover_slots_sync.pl to DEBUG2.

  16. Add more LOG and DEBUG messages for slot synchronization.

  17. Another try to fix BF failure introduced in commit ddd5f4f54a.

  18. Fix BF introduced in commit ddd5f4f54a.

  19. Add a slot synchronization function.

  20. Clean-ups for 776621a5e4 and 7329240437.

  21. Enhance libpqrcv APIs to support slot synchronization.

  22. Add a failover option to subscriptions.

  23. Allow setting failover property in the replication command.

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

  25. Add macros for looping through a List without a ListCell.

  26. Track conflict_reason in pg_replication_slots.

  27. Allow upgrades to preserve the full subscription's state.

  28. Add support for incremental backup.

  29. Simplify some logic in CreateReplicationSlot()

  30. Fix uninitialized access to InitialRunningXacts during decoding after ERROR.

  31. Flexible options for CREATE_REPLICATION_SLOT.

  32. Empty search_path in logical replication apply worker and walsender.

  33. Fix oldest xmin and LSN computation across repslots after advancing

  34. Require C99 (and thus MSCV 2013 upwards).