Horton

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

Ajin Cherian <itsajin@gmail.com>

View thread View on postgr.es
From: Ajin Cherian <itsajin@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Masahiko Sawada <sawada.mshk@gmail.com>, Peter Smith <smithpb2250@gmail.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2020-12-22T09:21:43Z
Lists: pgsql-hackers 
On Sat, Dec 19, 2020 at 2:13 PM Amit Kapila <amit.kapila16@gmail.com> wrote:

> Okay, I have changed the rollback_prepare API as discussed above and
> accordingly handle the case where rollback is received without prepare
> in apply_handle_rollback_prepared.


I have reviewed and tested your new patchset, I agree with all the
changes that you have made and have tested quite a few scenarios and
they seem to be working as expected.
No major comments but some minor observations:

Patch 1:
logical.c: 984
Comment should be "rollback prepared" rather than "abort prepared".

Patch 2:
decode.c: 737: The comments in the header of DecodePrepare seem out of
place, I think here it should describe what the function does rather
than what it does not.
reorderbuffer.c: 2422: It looks like pg_indent has mangled the
comments, the numbering is no longer aligned.

Patch 5:
worker.c: 753: Type: change "dont" to "don't"

Patch 6: logicaldecoding.sgml
logicaldecoding example is no longer correct. This was true prior to
the changes done to replay prepared transactions after a restart. Now
the whole transaction will get decoded again after the commit
prepared.

postgres=# COMMIT PREPARED 'test_prepared1';
COMMIT PREPARED
postgres=# select * from
pg_logical_slot_get_changes('regression_slot', NULL, NULL,
'two-phase-commit', '1');
    lsn    | xid |                    data
-----------+-----+--------------------------------------------
 0/168A060 | 529 | COMMIT PREPARED 'test_prepared1', txid 529
(1 row)

Patch 8:
worker.c: 2798 :
worker.c: 3445 : disabling two-phase in tablesync worker.
 considering new design of multiple commits in tablesync, do we need
to disable two-phase in tablesync?

Other than this I've noticed a few typos that are not in the patch but
in the surrounding code.
logical.c: 1383: Comment should mention stream_commit_cb not stream_abort_cb.
decode.c: 686 - Extra "it's" here:  "because it's it happened"

regards,
Ajin Cherian
Fujitsu Australia

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