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: Amit Kapila <amit.kapila16@gmail.com>
Cc: Bertrand Drouvot <bertranddrouvot.pg@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: 2024-01-27T06:31:52Z
Lists: pgsql-hackers

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On Saturday, January 27, 2024 11:43 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
> 
> On Thu, Jan 25, 2024 at 6:42 PM Zhijie Hou (Fujitsu) <houzj.fnst@fujitsu.com>
> wrote:
> >
> > Here is the V69 patch set which includes the following changes.
> >
> > V69-0001, V69-0002
> >
> 
> Few minor comments on v69-0001
> 1. In libpqrcv_create_slot(), I see we are using two types of syntaxes based on
> 'use_new_options_syntax' (aka server_version >= 15) whereas this new 'failover'
> option doesn't follow that. What is the reason of the same? I thought it is
> because older versions anyway won't support this option. However, I guess we
> should follow the syntax of the old server and let it error out.

Changed as suggested.

> BTW, did you test
> this patch with old server versions (say < 15 and >=15) by directly using
> replication commands, if so, what is the behavior of same?

Yes, I tested it. We cannot use new failover option or new
alter_replication_slot on server <17, the errors we will get are as follows:

Using failover option in create_replication_slot on server 15 ~ 16
	ERROR:  unrecognized option: failover
Using failover option in create_replication_slot on server < 15
	ERROR:  syntax error
Alter_replication_slot on server < 17
	ERROR:  syntax error at or near "ALTER_REPLICATION_SLOT"


> 
> 2.
>   }
> -
> + if (failover)
> + appendStringInfoString(&cmd, "FAILOVER, ");
> 
> Spurious line removal. Also, to follow a coding pattern similar to nearby code,
> let's have one empty line after handling of failover.

Changed.

> 
> 3.
> +/* ALTER_REPLICATION_SLOT slot */
> +alter_replication_slot:
> + K_ALTER_REPLICATION_SLOT IDENT '(' generic_option_list ')'
> 
> I think it would be better if we follow the create style by specifying syntax in
> comments as that can make the code easier to understand after future
> extensions to this command if any. See
> create_replication_slot:
> /* CREATE_REPLICATION_SLOT slot [TEMPORARY] PHYSICAL [options] */
> K_CREATE_REPLICATION_SLOT IDENT opt_temporary K_PHYSICAL
> create_slot_options

Changed.

Attach the V70 patch set which addressed above comments and Bertrand's comments in [1]

[1] https://www.postgresql.org/message-id/ZbNt1oRZRcdIAw2c%40ip-10-97-1-34.eu-west-3.compute.internal

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).