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: Ajin Cherian <itsajin@gmail.com>
Cc: Peter Smith <smithpb2250@gmail.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2020-12-17T03:42:52Z
Lists: pgsql-hackers 
On Thu, Dec 17, 2020 at 9:02 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Thu, Dec 17, 2020 at 7:02 AM Ajin Cherian <itsajin@gmail.com> wrote:
> >
> >
> > I have reviewed the changes, did not have any new comments.
> > While testing, I found an issue in this patch. During initialisation,
> > the pg_output is not initialised fully and the subscription parameters
> > are not all read. As a result, ctx->twophase could be
> > set to true , even if the subscription does not specify so. For this,
> > we need to make the following change in pgoutput.c:
> > pgoutput_startup(), similar to how streaming is handled.
> >
> >     /*
> >      * This is replication start and not slot initialization.
> >      *
> >      * Parse and validate options passed by the client.
> >      */
> >     if (!is_init)
> > {
> > :
> > :
> > }
> >  else
> > {
> >        /* Disable the streaming during the slot initialization mode. */
> >         ctx->streaming = false;
> > +        ctx->twophase = false
> >  }
> >
>
> makes sense.
>

On again thinking about this, I think it is good to disable it during
slot initialization but will it create any problem because during slot
initialization we don't stream any xact and stop processing WAL as
soon as we reach CONSISTENT_STATE? Did you observe any problem with
this?

-- 
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