Horton

Re: [HACKERS] logical decoding of two-phase transactions

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: Ajin Cherian <itsajin@gmail.com>, Peter Smith <smithpb2250@gmail.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2020-11-20T03:45:28Z
Lists: pgsql-hackers 
On Fri, Nov 20, 2020 at 7:54 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
>
> On Wed, Nov 18, 2020 at 12:42 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > > IIUC logical replication workers always set the origin's commit
> > > timestamp as the commit timestamp of the replicated transaction. OTOH,
> > > the timestamp of PREPARE, ‘prepare’ of pg_prepared_xacts, always uses
> > > the local timestamp even if the caller of PrepareTransaction() sets
> > > replorigin_session_origin_timestamp. In terms of user-visible
> > > timestamps of transaction operations, I think users might expect these
> > > timestamps are matched between the origin and its subscribers. But the
> > > pg_xact_commit_timestamp() is a function of the commit timestamp
> > > feature whereas ‘prepare’ is a pure timestamp when the transaction is
> > > prepared. So I’m not sure these timestamps really need to be matched,
> > > though.
> > >
> >
> > Yeah, I am not sure if it is a good idea for users to rely on this
> > especially if the same behavior is visible on the publisher as well.
> > We might want to think separately if there is a value in making
> > prepare-time to also rely on replorigin_session_origin_timestamp and
> > if so, that can be done as a separate patch. What do you think?
>
> I agree that we can think about it separately. If it's necessary we
> can make a patch later.
>

Thanks for the confirmation. Your review and suggestions are quite helpful.

-- 
With Regards,
Amit Kapila.

Commits

  1. Add prepare API support for streaming transactions in logical replication.

  2. Doc: minor improvements for logical replication protocol documentation.

  3. Fix test failure in 021_twophase.pl.

  4. Refactor to make common functions in proto.c and worker.c.

  5. Unify PostgresNode's new() and get_new_node() methods

  6. Fix potential buffer overruns in proto.c.

  7. Add support for prepared transactions to built-in logical replication.

  8. Refactor function parse_subscription_options.

  9. Allow enabling two-phase option via replication protocol.

  10. Don't use Asserts to check for violations of replication protocol.

  11. Improve psql tab completion for options of subcriptions and publications

  12. Rearrange logrep worker's snapshot handling some more.

  13. doc: Update information of new messages for logical replication.

  14. ALTER SUBSCRIPTION ... ADD/DROP PUBLICATION

  15. Allow pgoutput to send logical decoding messages.

  16. Refactor function parse_output_parameters.

  17. Avoid repeated decoding of prepared transactions after a restart.

  18. Fix an oversight in ReorderBufferFinishPrepared.

  19. Allow multiple xacts during table sync in logical replication.

  20. Fix replication of in-progress transactions in tablesync worker.

  21. Fix 'skip-empty-xacts' option in test_decoding for streaming mode.

  22. Use Enum for top level logical replication message types.

  23. Add support for streaming to built-in logical replication.

  24. Fix the logical streaming test.

  25. Implement streaming mode in ReorderBuffer.

  26. Extend the logical decoding output plugin API with stream methods.

  27. Store 2PC GID in commit/abort WAL recs for logical decoding