Horton

Re: Synchronizing slots from primary to standby

shveta malik <shveta.malik@gmail.com>

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From: shveta malik <shveta.malik@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: "Drouvot, Bertrand" <bertranddrouvot.pg@gmail.com>, Peter Smith <smithpb2250@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>, shveta malik <shveta.malik@gmail.com>
Date: 2023-10-18T10:28:03Z
Lists: pgsql-hackers 
On Wed, Oct 18, 2023 at 10:20 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Tue, Oct 17, 2023 at 9:06 PM Drouvot, Bertrand
> <bertranddrouvot.pg@gmail.com> wrote:
> >
> > On 10/13/23 10:35 AM, shveta malik wrote:
> > > On Thu, Oct 12, 2023 at 9:18 AM shveta malik <shveta.malik@gmail.com> wrote:
> > >>
> >
> > Code:
> >
> > +       True if this logical slot is enabled to be synced to the physical standbys
> > +       so that logical replication is not blocked after failover. Always false
> > +       for physical slots.
> >
> > Not sure "not blocked" is the right wording. "can be resumed from the new primary" maybe?
> >
>
> Yeah, your proposed wording sounds better. Also, I think we should
> document the impact of not doing so because I think the replication
> can continue after failover but it may lead to data inconsistency.
>
> BTW, I noticed that the code for Create Subscription is updated but
> not the corresponding docs. By looking at other parameters like
> password_required, streaming, two_phase where true or false indicates
> whether that option is enabled or not, I am thinking about whether
> enable_failover is an appropriate name for this option. The other
> option name that comes to mind is 'failover' where true indicates that
> the corresponding subscription will be enabled for failover. What do
> you think?

+1.  'failover' seems more in sync with other options' names.

> --
> 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).