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: Nisha Moond <nisha.moond412@gmail.com>
Cc: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>, Peter Smith <smithpb2250@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, "Drouvot, Bertrand" <bertranddrouvot.pg@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: 2023-12-13T06:09:07Z
Lists: pgsql-hackers 
On Tue, Dec 12, 2023 at 5:56 PM Nisha Moond <nisha.moond412@gmail.com> wrote:
>
> A review on v45 patch:
>
> If one creates a logical slot with failover=true as -
> select pg_create_logical_replication_slot('logical_slot','pgoutput',
> false, true, true);
>
> Then, uses the existing logical slot while creating a subscription -
> postgres=#  create subscription sub4 connection 'dbname=postgres
> host=localhost port=5433' publication pub1t4 WITH
> (slot_name=logical_slot, create_slot=false, failover=true);
> NOTICE:  changed the failover state of replication slot "logical_slot"
> on publisher to false
> CREATE SUBSCRIPTION
>
> Despite configuring logical_slot's failover to true and specifying
> failover=true during subscription creation, the NOTICE indicates a
> change in the failover state to 'false', without providing any
> explanation for this transition.
> It can be confusing for users, so IMO, the notice should include the
> reason for switching failover to 'false' or should give a hint to use
> either refresh=false or copy_data=false to enable failover=true for
> the slot as we do in other similar 'alter subscription...' scenarios.
>

Agree. The NOTICE should be more informative.

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).