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: "tanghy.fnst@fujitsu.com" <tanghy.fnst@fujitsu.com>
Cc: Peter Smith <smithpb2250@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, vignesh C <vignesh21@gmail.com>, Greg Nancarrow <gregn4422@gmail.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2021-07-06T11:18:18Z
Lists: pgsql-hackers

Attachments

On Fri, Jul 2, 2021 at 8:18 PM tanghy.fnst@fujitsu.com
<tanghy.fnst@fujitsu.com> wrote:
>
> Thanks for your patch. I met an issue while using it. When a transaction contains TRUNCATE, the subscriber reported an error: " ERROR:  no data left in message" and the data couldn't be replicated.
>
> Steps to reproduce the issue:
>
> (set logical_decoding_work_mem to 64kB at publisher so that streaming could work. )
>
> ------publisher------
> create table test (a int primary key, b varchar);
> create publication pub for table test;
>
> ------subscriber------
> create table test (a int primary key, b varchar);
> create subscription sub connection 'dbname=postgres' publication pub with(two_phase=on, streaming=on);
>
> ------publisher------
> BEGIN;
> TRUNCATE test;
> INSERT INTO test SELECT i, md5(i::text) FROM generate_series(1001, 6000) s(i);
> UPDATE test SET b = md5(b) WHERE mod(a,2) = 0;
> DELETE FROM test WHERE mod(a,3) = 0;
> COMMIT;
>
> The above case worked ok when remove 0004 patch, so I think it’s a problem of 0004 patch. Please have a look.

thanks for the test!
I hadn't updated the case where sending schema across was the first
change of the transaction as part of the decoding of the
truncate command. In this test case, the schema was sent across
without the stream start, hence the error on the apply worker.
I have updated with a fix. Please do a test and confirm.

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