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pg_wal_replay_pause()

A function for pausing WAL replay

pg_wal_replay_pause() is a system function for pausing WAL replay (recovery) on a standby.

pg_wal_replay_pause() was added in PostgreSQL 9.1 as pg_xlog_replay_pause().

Usage

pg_wal_replay_pause() → void

pg_wal_replay_pause() issues a request to PostgreSQL to pause replay; once successful, no further changes are applied. Execute pg_wal_replay_resume() to resume WAL replay.

Note that although pg_wal_replay_pause() returns immediately, there may be a delay before WAL replay is actually paused. The point at which reply was paused is noted in the PostgreSQL logfile with an entry like:

LOG:  00000: recovery has paused

From PostgreSQL 14 the function pg_get_wal_replay_pause_state() is also available to determine the status of a replay pause request.

Change history

Examples

Basic usage of pg_wal_replay_pause():

postgres=# SELECT pg_wal_replay_pause();
 pg_wal_replay_pause
---------------------

(1 row)

postgres=# SELECT pg_get_wal_replay_pause_state();
 pg_get_wal_replay_pause_state
-------------------------------
 paused
(1 row)

postgres=# SELECT pg_wal_replay_resume();
 pg_wal_replay_resume
----------------------

(1 row)

This generates entries like the following in the PostgreSQL logfile:

[2021-04-06 15:14:24 UTC] psql postgres postgres LOG:  00000: statement: SELECT pg_wal_replay_pause();
[2021-04-06 15:14:24 UTC]    LOG:  00000: recovery has paused
[2021-04-06 15:14:24 UTC]    HINT:  Execute pg_wal_replay_resume() to continue.
[2021-04-06 15:14:34 UTC] psql postgres postgres LOG:  00000: statement: SELECT pg_get_wal_replay_pause_state();
[2021-04-06 15:14:58 UTC] psql postgres postgres LOG:  00000: statement: SELECT pg_wal_replay_resume();

Categories

Replication, System function, WAL

See also

pg_wal_replay_resume(), pg_get_wal_replay_pause_state()