Horton

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

Peter Smith <smithpb2250@gmail.com>

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From: Peter Smith <smithpb2250@gmail.com>
To: vignesh C <vignesh21@gmail.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>, "tanghy.fnst@fujitsu.com" <tanghy.fnst@fujitsu.com>, Ajin Cherian <itsajin@gmail.com>, Greg Nancarrow <gregn4422@gmail.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2021-07-20T04:02:02Z
Lists: pgsql-hackers 
On Fri, Jul 16, 2021 at 4:08 PM vignesh C <vignesh21@gmail.com> wrote:
>
[...]
> Thanks for the updated patch, the patch applies cleanly and test passes:
> I had couple of comments:
> 1) Should we include "stream_prepare_cb" here  in
> logicaldecoding-streaming section of logicaldecoding.sgml
> documentation:
> To reduce the apply lag caused by large transactions, an output plugin
> may provide additional callback to support incremental streaming of
> in-progress transactions. There are multiple required streaming
> callbacks (stream_start_cb, stream_stop_cb, stream_abort_cb,
> stream_commit_cb and stream_change_cb) and two optional callbacks
> (stream_message_cb and stream_truncate_cb).
>

Modified in v98. The information about 'stream_prepare_cb' and friends
is given in detail in section 49.10 so I added a link to that page.


> 2) Should we add an example for stream_prepare_cb here  in
> logicaldecoding-streaming section of logicaldecoding.sgml
> documentation:
> One example sequence of streaming callback calls for one transaction
> may look like this:
>
> stream_start_cb(...);   <-- start of first block of changes
>   stream_change_cb(...);
>   stream_change_cb(...);
>   stream_message_cb(...);
>   stream_change_cb(...);
>   ...
>   stream_change_cb(...);
> stream_stop_cb(...);    <-- end of first block of changes
>
> stream_start_cb(...);   <-- start of second block of changes
>   stream_change_cb(...);
>   stream_change_cb(...);
>   stream_change_cb(...);
>   ...
>   stream_message_cb(...);
>   stream_change_cb(...);
> stream_stop_cb(...);    <-- end of second block of changes
>
> stream_commit_cb(...);  <-- commit of the streamed transaction
>

Modified in v98. I felt it would be too verbose to add another full
example since it would be 90% the same as the current example. So I
have combined the information.

------
Kind Regards,
Peter Smith.
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