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: shveta malik <shveta.malik@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>
Cc: Peter Smith <smithpb2250@gmail.com>, "Drouvot, Bertrand" <bertranddrouvot.pg@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>, Ajin Cherian <itsajin@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: 2023-12-18T12:12:26Z
Lists: pgsql-hackers

Attachments

On Friday, December 15, 2023 1:32 PM shveta malik <shveta.malik@gmail.com> wrote:
> 
> TODO:
> --Address the test comments in [1] for 050_standby_failover_slots_sync.pl
> --Review the feasibility of addressing one pending comment (comment 13 in
> [5]) of 'r'->'n' conversion.

Here is the V49 patch set which addressed above TODO items.

The patch also includes the following changes:

V49-0001

1) added some documents to mention it's user responsibility to ensure the table
   sync is completed before subscriber to the new primary.
2) fix one CFbot failure in 050_standby_failover_slots_sync.pl.

V49-0002
1) added few comments to mention why we retain the READY state after promotion.
2) Prevent user from altering the slots that is being synced.
3) fix one CFbot failure in 050_standby_failover_slots_sync.pl.
4) Improve the 050_standby_failover_slots_sync.pl to remove some unnecessary
   operations.

V49-0003

There is one unstable test in V48-0002 which is to validate the restart_lsn of
synced slot. We test it by checking "'$primary_restart_lsn' <= restart_lsn"
which would wrongly allow the standby to go ahead of primary. And it may fail
randomly as standby may still be lagging behind primary if the slot-sync worker
has gone to longer nap (10 sec) and has not taken the slots-changes yet.  And
we cannot put sleep of 10sec here.

We may consider removing this test as it may be enough to test
that logical replication is proceeding well from the synced slots on new
primary. So, I temporarily move it into a separately patch for review.


Thanks Ajin for working on the testcases improvement.


> 
> [1]:
> https://www.postgresql.org/message-id/CAHut%2BPtOc7J_n24HJ6f_dFWTu
> D3X2ApOByQzZf6jZz%2B0wb-ebQ%40mail.gmail.com
> [5]:
> https://www.postgresql.org/message-id/CAJpy0uDcOf5Hvk_CdCCAbfx9SY%
> 2Bog%3D%3D%3DtgiuhWKzkYyqebui9g%40mail.gmail.com

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).