Replication Origin Functions

A replication origin records how far changes from some remote source have been applied, as the LSN of that source. Every subscription has one, named pg_<subscription oid>, and you can create your own to track any other replication you run. Origins belong to the whole server, like roles, and are listed in pg_replication_origin, with their progress in pg_replication_origin_status. The progress is stored durably: it commits with the transaction that set it.

The functions work as in PostgreSQL, and only superusers may call them.

Function	Description
`pg_replication_origin_create(node_name)`	Creates an origin and returns its oid. Names `any`, `none` and names starting with `pg_` are reserved.
`pg_replication_origin_drop(node_name)`	Drops an origin. A subscription's origin goes away with the subscription.
`pg_replication_origin_oid(node_name)`	Returns the oid of an origin, or `NULL` when there is none.
`pg_replication_origin_progress(node_name, flush)`	Returns the LSN up to which the origin has applied, or `NULL` before it has any. Progress is always durable, so `flush` makes no difference.
`pg_replication_origin_advance(node_name, lsn)`	Sets the origin's progress to `lsn`, also backwards. The origin must not be in use by a session or by a running subscription.
`pg_replication_origin_session_setup(node_name [, pid])`	Makes the origin the current session's origin. With `pid`, shares the origin that session `pid` has set up.
`pg_replication_origin_session_reset()`	Releases the current session's origin.
`pg_replication_origin_session_is_setup()`	Whether the current session has an origin.
`pg_replication_origin_session_progress(flush)`	The progress of the current session's origin.
`pg_replication_origin_xact_setup(origin_lsn, origin_timestamp)`	Makes the current transaction advance the session's origin to `origin_lsn` when it commits.
`pg_replication_origin_xact_reset()`	Undoes `pg_replication_origin_xact_setup()` in the current transaction.

Creating and advancing an origin

SQL

SELECT pg_replication_origin_create('docs_origin');
SELECT pg_replication_origin_advance('docs_origin', '0/16B3748');
SELECT pg_replication_origin_progress('docs_origin', true) AS remote_lsn;

 remote_lsn
------------
 0/16B3748

Recording progress with the applied rows

A session that applies changes from a source sets up the origin once, then marks each transaction with the source position it applies. The position commits together with the rows, so after a crash the origin shows exactly what was applied.

SQL

SELECT pg_replication_origin_session_setup('docs_origin');
CREATE TABLE docs_origin_rows (id INTEGER);
BEGIN;
SELECT pg_replication_origin_xact_setup('0/16B3800', now());
INSERT INTO docs_origin_rows VALUES (1);
COMMIT;
SELECT pg_replication_origin_session_progress(true) AS remote_lsn;
SELECT pg_replication_origin_session_reset();
DROP TABLE docs_origin_rows;
SELECT pg_replication_origin_drop('docs_origin');

 remote_lsn
------------
 0/16B3800

local_lsn in pg_replication_origin_status is always 0/0. Marking a transaction with an origin does not filter its changes from anything, since SereneDB does not publish changes.

Creating and advancing an origin​

Recording progress with the applied rows​

Creating and advancing an origin

Recording progress with the applied rows