Horton

Re: Synchronizing slots from primary to standby

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Peter Smith <smithpb2250@gmail.com>
Cc: shveta malik <shveta.malik@gmail.com>, Ajin Cherian <itsajin@gmail.com>, Bertrand Drouvot <bertranddrouvot.pg@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>, Dilip Kumar <dilipbalaut@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>, Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: 2024-01-24T04:09:01Z
Lists: pgsql-hackers 
On Wed, Jan 24, 2024 at 8:52 AM Peter Smith <smithpb2250@gmail.com> wrote:
>
> Here are some comments for patch v66-0001.
>
> ======
> doc/src/sgml/catalogs.sgml
>
> 1.
> +      <para>
> +       If true, the associated replication slots (i.e. the main slot and the
> +       table sync slots) in the upstream database are enabled to be
> +       synchronized to the physical standbys
> +      </para></entry>
>
> /physical standbys/physical standby/
>
> I wondered if it is better just to say singular "standby" instead of
> "standbys" in places like this; e.g. plural might imply cascading for
> some readers.
>

I don't think it is confusing as we used in a similar way in docs. We
can probably avoid using physical in places similar to above as that
is implied

>
>
> ======
> src/backend/replication/slotfuncs.c
>
> 11. create_physical_replication_slot
>
>   /* acquire replication slot, this will check for conflicting names */
>   ReplicationSlotCreate(name, false,
> -   temporary ? RS_TEMPORARY : RS_PERSISTENT, false);
> +   temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
> +   false);
>
> Having an inline comment might be helpful here instead of passing "false,false"
>
> SUGGESTION
> ReplicationSlotCreate(name, false,
>  temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
>  false /* failover */);
>

I don't think we follow to use of inline comments. I feel that
sometimes makes code difficult to read considering when we have
multiple such parameters.

-- 
With Regards,
Amit Kapila.

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).