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: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Cc: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>, shveta malik <shveta.malik@gmail.com>, Ajin Cherian <itsajin@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.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>, Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: 2024-01-25T10:24:45Z
Lists: pgsql-hackers 
On Thu, Jan 25, 2024 at 1:25 PM Bertrand Drouvot
<bertranddrouvot.pg@gmail.com> wrote:
>
> On Thu, Jan 25, 2024 at 02:57:30AM +0000, Zhijie Hou (Fujitsu) wrote:
> >
> > Agreed. I split the original 0001 patch into 3 patches as suggested.
> > Here is the V68 patch set.

Thanks, I have pushed 0001.

>
> Thanks!
>
> Some comments.
>
> Looking at 0002:
>
> 1 ===
>
> +      <para>The following options are supported:</para>
>
> What about "The following option is supported"? (as currently only the "FAILOVER"
> is)
>
> 2 ===
>
> What about adding some TAP tests too? (I can see that ALTER_REPLICATION_SLOT test
> is added in v68-0004 but I think having some in 0002 would make sense too).
>

The subscription tests in v68-0003 will test this functionality. The
one advantage of adding separate tests for this is that if in the
future we extend this replication command, it could be convenient to
test various options. However, the same could be said about existing
replication commands as well. But is it worth having extra tests which
will be anyway covered in the next commit in a few days?

I understand that it is a good idea and makes one comfortable to have
tests for each separate commit but OTOH, in the longer term it will
just be adding more test time without achieving much benefit. I think
we can tell explicitly in the commit message of this patch that the
subsequent commit will cover the tests for this functionality

One minor comment on 0002:
+          so that logical replication can be resumed after failover.
+         </para>

Can we move this and similar comments or doc changes to the later 0004
patch where we are syncing the slots?


-- 
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).