Horton

Re: Synchronizing slots from primary to standby

Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

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From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>
Cc: Amit Kapila <amit.kapila16@gmail.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: 2024-01-25T07:55:32Z
Lists: pgsql-hackers 
Hi,

On Thu, Jan 25, 2024 at 02:57:30AM +0000, Zhijie Hou (Fujitsu) wrote:
> On Wednesday, January 24, 2024 6:31 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> > 
> > On Tue, Jan 23, 2024 at 5:13 PM shveta malik <shveta.malik@gmail.com> wrote:
> > >
> > > Thanks Ajin for testing the patch. PFA v66 which fixes this issue.
> > >
> > 
> > I think we should try to commit the patch as all of the design concerns are
> > resolved now. To achieve that, can we split the failover setting patch into the
> > following: (a) setting failover property via SQL commands and display it in
> > pg_replication_slots (b) replication protocol command (c) failover property via
> > subscription commands?
> > 
> > It will make each patch smaller and it would be easier to detect any problem in
> > the same after commit.
> 
> Agreed. I split the original 0001 patch into 3 patches as suggested.
> Here is the V68 patch set.

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).

Looking at 0003:

1 ===

+      parameter specified in the subscription. When creating the slot,
+      ensure the slot <literal>failover</literal> property matches the
+      <link linkend="sql-createsubscription-params-with-failover"><literal>failover</literal></link>
+      parameter value of the subscription.

What about explaining what would be the consequence of not doing so?

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com

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).