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

On Wed, Jun 23, 2021 at 3:18 PM vignesh C <vignesh21(at)gmail(dot)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