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Allow enabling two-phase option via replication protocol.

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Extend the replication command CREATE_REPLICATION_SLOT to support the
TWO_PHASE option. This will allow decoding commands like PREPARE
TRANSACTION, COMMIT PREPARED and ROLLBACK PREPARED for slots created with
this option. The decoding of the transaction happens at prepare command.

This patch also adds support of two-phase in pg_recvlogical via a new
option --two-phase.

This option will also be used by future patches that allow streaming of
transactions at prepare time for built-in logical replication. With this,
the out-of-core logical replication solutions can enable replication of
two-phase transactions via replication protocol.

Author: Ajin Cherian
Reviewed-By: Jeff Davis, Vignesh C, Amit Kapila
Discussion:
https://postgr.es/m/02DA5F5E-CECE-4D9C-8B4B-418077E2C010@postgrespro.ru
https://postgr.es/m/64b9f783c6e125f18f88fbc0c0234e34e71d8639.camel@j-davis.com
This commit is contained in:
Amit Kapila
2021-06-30 08:45:47 +05:30
parent 17707c059c
commit cda03cfed6
12 changed files with 143 additions and 13 deletions
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23
doc/src/sgml/logicaldecoding.sgml
View File

@ -144,16 +144,19 @@ postgres=# SELECT pg_drop_replication_slot('regression_slot');
</programlisting>
<para>
The following example shows how logical decoding is controlled over the
The following examples shows how logical decoding is controlled over the
streaming replication protocol, using the
program <xref linkend="app-pgrecvlogical"/> included in the PostgreSQL
distribution. This requires that client authentication is set up to allow
replication connections
(see <xref linkend="streaming-replication-authentication"/>) and
that <varname>max_wal_senders</varname> is set sufficiently high to allow
an additional connection.
an additional connection. The second example shows how to stream two-phase
transactions. Before you use two-phase commands, you must set
<xref linkend="guc-max-prepared-transactions"/> to atleast 1.
</para>
<programlisting>
Example 1:
$ pg_recvlogical -d postgres --slot=test --create-slot
$ pg_recvlogical -d postgres --slot=test --start -f -
<keycombo action="simul"><keycap>Control</keycap><keycap>Z</keycap></keycombo>
@ -164,6 +167,22 @@ table public.data: INSERT: id[integer]:4 data[text]:'4'
COMMIT 693
<keycombo action="simul"><keycap>Control</keycap><keycap>C</keycap></keycombo>
$ pg_recvlogical -d postgres --slot=test --drop-slot
Example 2:
$ pg_recvlogical -d postgres --slot=test --create-slot --two-phase
$ pg_recvlogical -d postgres --slot=test --start -f -
<keycombo action="simul"><keycap>Control</keycap><keycap>Z</keycap></keycombo>
$ psql -d postgres -c "BEGIN;INSERT INTO data(data) VALUES('5');PREPARE TRANSACTION 'test';"
$ fg
BEGIN 694
table public.data: INSERT: id[integer]:5 data[text]:'5'
PREPARE TRANSACTION 'test', txid 694
<keycombo action="simul"><keycap>Control</keycap><keycap>Z</keycap></keycombo>
$ psql -d postgres -c "COMMIT PREPARED 'test';"
$ fg
COMMIT PREPARED 'test', txid 694
<keycombo action="simul"><keycap>Control</keycap><keycap>C</keycap></keycombo>
$ pg_recvlogical -d postgres --slot=test --drop-slot
</programlisting>
<para>

16
doc/src/sgml/protocol.sgml
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@ -1914,7 +1914,7 @@ The commands accepted in replication mode are:
</varlistentry>
<varlistentry id="protocol-replication-create-slot" xreflabel="CREATE_REPLICATION_SLOT">
<term><literal>CREATE_REPLICATION_SLOT</literal> <replaceable class="parameter">slot_name</replaceable> [ <literal>TEMPORARY</literal> ] { <literal>PHYSICAL</literal> [ <literal>RESERVE_WAL</literal> ] | <literal>LOGICAL</literal> <replaceable class="parameter">output_plugin</replaceable> [ <literal>EXPORT_SNAPSHOT</literal> | <literal>NOEXPORT_SNAPSHOT</literal> | <literal>USE_SNAPSHOT</literal> ] }
<term><literal>CREATE_REPLICATION_SLOT</literal> <replaceable class="parameter">slot_name</replaceable> [ <literal>TEMPORARY</literal> ] { <literal>PHYSICAL</literal> [ <literal>RESERVE_WAL</literal> ] | <literal>LOGICAL</literal> <replaceable class="parameter">output_plugin</replaceable> [ <literal>EXPORT_SNAPSHOT</literal> | <literal>NOEXPORT_SNAPSHOT</literal> | <literal>USE_SNAPSHOT</literal> | <literal>TWO_PHASE</literal> ] }
<indexterm><primary>CREATE_REPLICATION_SLOT</primary></indexterm>
</term>
<listitem>
@ -1955,6 +1955,20 @@ The commands accepted in replication mode are:
</listitem>
</varlistentry>
<varlistentry>
<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>
<varlistentry>
<term><literal>RESERVE_WAL</literal></term>
<listitem>

16
doc/src/sgml/ref/pg_recvlogical.sgml
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@ -65,6 +65,11 @@ PostgreSQL documentation
<option>--plugin</option>, for the database specified
by <option>--dbname</option>.
</para>
<para>
The <option>--two-phase</option> can be specified with
<option>--create-slot</option> to enable two-phase decoding.
</para>
</listitem>
</varlistentry>
@ -256,6 +261,17 @@ PostgreSQL documentation
</listitem>
</varlistentry>
<varlistentry>
<term><option>-t</option></term>
<term><option>--two-phase</option></term>
<listitem>
<para>
Enables two-phase decoding. This option should only be specified with
<option>--create-slot</option>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-v</option></term>
<term><option>--verbose</option></term>