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: Peter Smith <smithpb2250@gmail.com>
Cc: Ajin Cherian <itsajin@gmail.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2020-10-21T08:43:08Z
Lists: pgsql-hackers 
On Wed, Oct 21, 2020 at 1:38 PM Peter Smith <smithpb2250@gmail.com> wrote:
>
> The PG docs for PREPARE TRANSACTION [1] don't say anything about an
> empty (zero length) transaction-id.
> e.g. PREPARE TRANSACTION '';
> [1] https://www.postgresql.org/docs/current/sql-prepare-transaction.html
>
> ~
>
> Meanwhile, during testing I found the 2PC prepare hangs when an empty
> id is used.
>

Can you please take an example to explain what you are trying to say?
I have tried below and doesn't face any problem:

postgres=# Begin;
BEGIN
postgres=*# select txid_current();
 txid_current
--------------
          534
(1 row)
postgres=*# Prepare Transaction 'foo';
PREPARE TRANSACTION
postgres=# Commit Prepared 'foo';
COMMIT PREPARED
postgres=# Begin;
BEGIN
postgres=*# Prepare Transaction 'foo';
PREPARE TRANSACTION
postgres=# Commit Prepared 'foo';
COMMIT PREPARED

-- 
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