Horton

Re: Synchronizing slots from primary to standby

Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

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From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: shveta malik <shveta.malik@gmail.com>, "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>, Masahiko Sawada <sawada.mshk@gmail.com>, Peter Smith <smithpb2250@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: 2024-02-28T06:37:42Z
Lists: pgsql-hackers 
Hi,

On Wed, Feb 28, 2024 at 08:49:19AM +0530, Amit Kapila wrote:
> On Mon, Feb 26, 2024 at 9:13 AM shveta malik <shveta.malik@gmail.com> wrote:
> >
> > On Fri, Feb 23, 2024 at 7:41 PM Bertrand Drouvot
> > <bertranddrouvot.pg@gmail.com> wrote:
> > >
> > > Hi,
> > > > I think to set secure search path for remote connection, the standard approach
> > > > could be to extend the code in libpqrcv_connect[1], so that we don't need to schema
> > > > qualify all the operators in the queries.
> > > >
> > > > And for local connection, I agree it's also needed to add a
> > > > SetConfigOption("search_path", "" call in the slotsync worker.
> > > >
> > > > [1]
> > > > libpqrcv_connect
> > > > ...
> > > >       if (logical)
> > > > ...
> > > >               res = libpqrcv_PQexec(conn->streamConn,
> > > >                                                         ALWAYS_SECURE_SEARCH_PATH_SQL);
> > > >
> > >
> > > Agree, something like in the attached? (it's .txt to not disturb the CF bot).
> >
> > Thanks for the patch, changes look good. I have corporated it in the
> > patch which addresses the rest of your comments in [1]. I have
> > attached the patch as .txt
> >
> 
> Few comments:
> ===============
> 1.
> - if (logical)
> + if (logical || !replication)
>   {
> 
> Can we add a comment about connection types that require
> ALWAYS_SECURE_SEARCH_PATH_SQL?

Yeah, will do.

> 
> 2.
> Can we add a test case to demonstrate that the '=' operator can be
> hijacked to do different things when the slotsync worker didn't use
> ALWAYS_SECURE_SEARCH_PATH_SQL?

I don't think that's good to create a test to show how to hijack an operator
within a background worker.

I had a quick look and did not find existing tests in this area around
ALWAYS_SECURE_SEARCH_PATH_SQL / search_patch and background worker.

Such a test would:

- "just" ensure that search_path works as expected
- show how to hijack an operator within a background worker

Based on the above I don't think that such a test is worth it.

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com

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).