pg_switch_wal()

pg_switch_wal() is a system function which forces PostgreSQL to switch to a new WAL file.

    pg_switch_wal() returns the end LSN + 1 of the old WAL file.

    However, if there has been no activity which generates WAL since the last WAL file switch, a switch will not be carried out and the start location of the current WAL file will be returned.

    pg_switch_wal() can only be executed on a primary server (i.e. not a read-only standby).

    postgres=# SELECT pg_switch_wal();

    pg_switch_wal

    —————

    0/161E050

     If there has been no activity which generated WAL since the last WAL file  switch, a new WAL file will not be created:

    postgres=# SELECT pg_walfile_name(pg_switch_wal()), pg_walfile_name(pg_switch_wal());

     pg_walfile_name      |     pg_walfile_name     

————————–+————————–

 000000010000000200000086 | 000000010000000200000086

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