Horton

RE: Synchronizing slots from primary to standby

Zhijie Hou (Fujitsu) <houzj.fnst@fujitsu.com>

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From: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>
To: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Cc: Peter Smith <smithpb2250@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, shveta malik <shveta.malik@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, Ajin Cherian <itsajin@gmail.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: 2024-02-29T03:16:15Z
Lists: pgsql-hackers 
On Wednesday, February 28, 2024 7:36 PM Bertrand Drouvot <bertranddrouvot.pg@gmail.com> wrote:
> 
> On Wed, Feb 28, 2024 at 02:23:27AM +0000, Zhijie Hou (Fujitsu) wrote:
> > Attach the V100 patch set which addressed above comments.
> 
> A few random comments:

Thanks for the comments!

> 
> 1 ===
> 
> +       if (!ok)
> +       {
> +               GUC_check_errdetail("List syntax is invalid.");
> +       }
> 
> What about to get rid of the brackets here?

I personally prefer the current style.

> 
> 2 ===
> 
> +
> +       /*
> +        * If the replication slots' data have been initialized, verify if the
> +        * specified slots exist and are logical slots.
> +        */
> 
> remove the empty line above the comment?

I feel it would be clean to have an empty line before the comments.

> 
> 3 ===
> 
> +check_standby_slot_names(char **newval, void **extra, GucSource source)
> +{
> +       if ((*newval)[0] == '\0')
> +               return true;
> 
> I think "**newval == '\0'" is easier to read but that's a matter of taste and
> check_synchronous_standby_names() is already using the same so it's a nit.

I don't have a strong opinion on this, so will change if others also feel so.

> 
> 4 ===
> 
> Regarding the test, what about adding one to test the "new" behavior
> discussed up-thread? (logical replication will wait if slot mentioned in
> standby_slot_names is dropped and/or does not exist when the engine starts?)

Will think about this.

Best Regards,
Hou zj

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).