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Add optional pid parameter to pg_replication_origin_session_setup().

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Commit 216a784829 introduced parallel apply workers, allowing multiple
processes to share a replication origin. To support this,
replorigin_session_setup() was extended to accept a pid argument
identifying the process using the origin.

This commit exposes that capability through the SQL interface function
pg_replication_origin_session_setup() by adding an optional pid parameter.
This enables multiple processes to coordinate replication using the same
origin when using SQL-level replication functions.

This change allows the non-builtin logical replication solutions to
implement parallel apply for large transactions.

Additionally, an existing internal error was made user-facing, as it can
now be triggered via the exposed SQL API.

Author: Doruk Yilmaz <doruk@mixrank.com>
Author: Hayato Kuroda <kuroda.hayato@fujitsu.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Reviewed-by: Euler Taveira <euler@eulerto.com>
Discussion: https://postgr.es/m/CAMPB6wfe4zLjJL8jiZV5kjjpwBM2=rTRme0UCL7Ra4L8MTVdOg@mail.gmail.com
Discussion: https://postgr.es/m/CAE2gYzyTSNvHY1+iWUwykaLETSuAZsCWyryokjP6rG46ZvRgQA@mail.gmail.com
This commit is contained in:
Amit Kapila
2025-09-19 05:38:40 +00:00
parent 8aac5923a3
commit 5b148706c5
11 changed files with 193 additions and 10 deletions
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23
doc/src/sgml/func/func-admin.sgml
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@@ -1315,7 +1315,7 @@ postgres=# SELECT '0/0'::pg_lsn + pd.segment_number * ps.setting::int + :offset
<indexterm>
<primary>pg_replication_origin_session_setup</primary>
</indexterm>
<function>pg_replication_origin_session_setup</function> ( <parameter>node_name</parameter> <type>text</type> )
<function>pg_replication_origin_session_setup</function> ( <parameter>node_name</parameter> <type>text</type> <optional>, <parameter>pid</parameter> <type>integer</type> <literal>DEFAULT</literal> <literal>0</literal></optional> )
<returnvalue>void</returnvalue>
</para>
<para>
@@ -1323,7 +1323,26 @@ postgres=# SELECT '0/0'::pg_lsn + pd.segment_number * ps.setting::int + :offset
origin, allowing replay progress to be tracked.
Can only be used if no origin is currently selected.
Use <function>pg_replication_origin_session_reset</function> to undo.
</para></entry>
If multiple processes can safely use the same replication origin (for
example, parallel apply processes), the optional <parameter>pid</parameter>
parameter can be used to specify the process ID of the first process.
The first process must provide <parameter>pid</parameter> equals to
<literal>0</literal> and the other processes that share the same
replication origin should provide the process ID of the first process.
</para>
<caution>
<para>
When multiple processes share the same replication origin, it is critical
to maintain commit order to prevent data inconsistency. While processes
may send operations out of order, they must commit transactions in the
correct sequence to ensure proper replication consistency. The recommended workflow
for each worker is: set up the replication origin session with the first process's PID,
apply changes within transactions, call <function>pg_replication_origin_xact_setup</function>
with the LSN and commit timestamp before committing, then commit the
transaction only if everything succeeded.
</para>
</caution>
</entry>
</row>
<row>