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CHECKPOINT
An SQL command which forces a checkpoint
CHECKPOINT is an SQL command which forces PostgreSQL to carry out an immediate checkpoint, after which the on-disk datafiles are guaranteed to be up-to-date as of the point the command was executed.
CHECKPOINT was added in PostgreSQL 7.1.
Usage
CHECKPOINT can only be executed by a superuser.
Following execution of the CHECKPOINT command, the checkpoints_req column in pg_stat_bgwriter will be incremented.
Change history
- PostgreSQL 7.1
- added (commit f0e37a85)
Examples
Execution of the CHECKPOINT command:
postgres=# CHECKPOINT; CHECKPOINT
Log file output during the checkpoint operation (assuming log_checkpoints is set to on):
[2021-03-29 12:28:06 UTC] LOG: 00000: checkpoint starting: immediate force wait [2021-03-29 12:28:06 UTC] LOG: 00000: checkpoint complete: wrote 33 buffers (0.2%); 0 WAL file(s) added, 0 removed, 0 recycled; write=0.001 s, sync=0.001 s, total=0.001 s; sync files=0, longest=0.000 s, average=0.000 s; distance=132 kB, estimate=132 kB
The checkpoints_req column in pg_stat_bgwriter will be incremented after each execution of the CHECKPOINT command:
postgres=# SELECT checkpoints_timed, checkpoints_req FROM pg_stat_bgwriter;
checkpoints_timed | checkpoints_req
-------------------+-----------------
0 | 0
(1 row)
postgres=# CHECKPOINT;
CHECKPOINT
postgres=# SELECT checkpoints_timed, checkpoints_req FROM pg_stat_bgwriter;
checkpoints_timed | checkpoints_req
-------------------+-----------------
0 | 1
(1 row)
References
- PostgreSQL documentation: CHECKPOINT