Horton

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

Ajin Cherian <itsajin@gmail.com>

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From: Ajin Cherian <itsajin@gmail.com>
To: vignesh C <vignesh21@gmail.com>
Cc: Greg Nancarrow <gregn4422@gmail.com>, Peter Smith <smithpb2250@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, "tanghy.fnst@fujitsu.com" <tanghy.fnst@fujitsu.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2021-06-23T10:40:46Z
Lists: pgsql-hackers

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On Wed, Jun 23, 2021 at 3:18 PM vignesh C <vignesh21@gmail.com> wrote:

> Thanks for the updated patch.
> The patch v89-0001-Add-option-to-set-two-phase-in-CREATE_REPLICATIO.patch
> has the following:
> +       <term><literal>TWO_PHASE</literal></term>
> +       <listitem>
> +        <para>
> +         Specify that this logical replication slot supports decoding
> of two-phase
> +         transactions. With this option, two-phase commands like
> +         <literal>PREPARE TRANSACTION</literal>, <literal>COMMIT
> PREPARED</literal>
> +         and <literal>ROLLBACK PREPARED</literal> are decoded and transmitted.
> +         The transaction will be decoded and transmitted at
> +         <literal>PREPARE TRANSACTION</literal> time.
> +        </para>
> +       </listitem>
> +      </varlistentry>
>
> The patch v89-0003-Add-support-for-prepared-transactions-to-built-i.patch
> has the following:
> +       <term><literal>TWO_PHASE</literal></term>
> +       <listitem>
> +        <para>
> +         Specify that this replication slot supports decode of two-phase
> +         transactions. With this option, two-phase commands like
> +         <literal>PREPARE TRANSACTION</literal>, <literal>COMMIT
> PREPARED</literal>
> +         and <literal>ROLLBACK PREPARED</literal> are decoded and transmitted.
> +         The transaction will be decoded and transmitted at
> +         <literal>PREPARE TRANSACTION</literal> time.
> +        </para>
> +       </listitem>
> +      </varlistentry>
>
> We can remove one of them.

I missed this. Updated.

Also fixed this comment below which I had missed in my last patch:

>4) You could mention "Before you use two-phase commit commands, you
>must set max_prepared_transactions to at least 1" for example 2.
> $ pg_recvlogical -d postgres --slot=test --drop-slot
>+
>+$ pg_recvlogical -d postgres --slot=test --create-slot --two-phase
>+$ pg_recvlogical -d postgres --slot=test --start -f -

Comment 6:
>6)  This should be before verbose, the options are printed alphabetically
>       printf(_("  -v, --verbose          output verbose messages\n"));
>+       printf(_("  -t, --two-phase        enable two-phase decoding
>when creating a slot\n"));
>        printf(_("  -V, --version          output version information,
>then exit\n"));

This was also fixed in the last patch.

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