Horton

Re: Synchronizing slots from primary to standby

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>
Cc: shveta malik <shveta.malik@gmail.com>, Peter Smith <smithpb2250@gmail.com>, Bertrand Drouvot <bertranddrouvot.pg@gmail.com>, Ajin Cherian <itsajin@gmail.com>, Masahiko Sawada <sawada.mshk@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: 2024-01-30T06:01:18Z
Lists: pgsql-hackers 
On Mon, Jan 29, 2024 at 6:47 PM Zhijie Hou (Fujitsu)
<houzj.fnst@fujitsu.com> wrote:
>
> On Monday, January 29, 2024 7:30 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
>
> > ===================
> > 1.
> > parse_subscription_options()
> > {
> > ...
> > /*
> > * We've been explicitly asked to not connect, that requires some
> > * additional processing.
> > */
> > if (!opts->connect && IsSet(supported_opts, SUBOPT_CONNECT)) {
> >
> > Here, along with other options, we need an explicit check for failover, so that if
> > connect=false and failover=true, the statement should give error. I was
> > expecting the below statement to fail but it passed with WARNING.
> > postgres=# create subscription sub2 connection 'dbname=postgres'
> > publication pub2 with(connect=false, failover=true);
> > WARNING:  subscription was created, but is not connected
> > HINT:  To initiate replication, you must manually create the replication slot,
> > enable the subscription, and refresh the subscription.
> > CREATE SUBSCRIPTION
>
> Added.
>

In this regard, I feel we don't need to dump/restore the 'FAILOVER'
option non-binary upgrade paths similar to the 'ENABLE' option. For
binary upgrade, if the failover option is enabled, then we can enable
it using Alter Subscription SET (failover=true). Let's add one test
corresponding to this behavior in
postgresql\src\bin\pg_upgrade\t\004_subscription.

Additionally, we need to update the pg_dump docs for the 'failover'
option. See "When dumping logical replication subscriptions, .." [1].
I think we also need to update the connect option docs in CREATE
SUBSCRIPTION [2].

[1] - https://www.postgresql.org/docs/devel/app-pgdump.html
[2] - https://www.postgresql.org/docs/devel/sql-createsubscription.html

-- 
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).