pg_checksums(1) PostgreSQL 17.4 Documentation pg_checksums(1)
NAME
pg_checksums - enable, disable or check data checksums in a PostgreSQL
database cluster
SYNOPSIS
pg_checksums [option...] [[-D | --pgdata]datadir]
DESCRIPTION
pg_checksums checks, enables or disables data checksums in a PostgreSQL
cluster. The server must be shut down cleanly before running
pg_checksums. When verifying checksums, the exit status is zero if
there are no checksum errors, and nonzero if at least one checksum
failure is detected. When enabling or disabling checksums, the exit
status is nonzero if the operation failed.
When verifying checksums, every file in the cluster is scanned. When
enabling checksums, each relation file block with a changed checksum is
rewritten in-place. Disabling checksums only updates the file
pg_control.
OPTIONS
The following command-line options are available:
-D directory
--pgdata=directory
Specifies the directory where the database cluster is stored.
-c
--check
Checks checksums. This is the default mode if nothing else is
specified.
-d
--disable
Disables checksums.
-e
--enable
Enables checksums.
-f filenode
--filenode=filenode
Only validate checksums in the relation with filenode filenode.
-N
--no-sync
By default, pg_checksums will wait for all files to be written
safely to disk. This option causes pg_checksums to return without
waiting, which is faster, but means that a subsequent operating
system crash can leave the updated data directory corrupt.
Generally, this option is useful for testing but should not be used
on a production installation. This option has no effect when using
--check.
-P
--progress
Enable progress reporting. Turning this on will deliver a progress
report while checking or enabling checksums.
--sync-method=method
When set to fsync, which is the default, pg_checksums will
recursively open and synchronize all files in the data directory.
The search for files will follow symbolic links for the WAL
directory and each configured tablespace.
On Linux, syncfs may be used instead to ask the operating system to
synchronize the whole file systems that contain the data directory,
the WAL files, and each tablespace. See recovery_init_sync_method
for information about the caveats to be aware of when using syncfs.
This option has no effect when --no-sync is used.
-v
--verbose
Enable verbose output. Lists all checked files.
-V
--version
Print the pg_checksums version and exit.
-?
--help
Show help about pg_checksums command line arguments, and exit.
ENVIRONMENT
PGDATA
Specifies the directory where the database cluster is stored; can
be overridden using the -D option.
PG_COLOR
Specifies whether to use color in diagnostic messages. Possible
values are always, auto and never.
NOTES
Enabling checksums in a large cluster can potentially take a long time.
During this operation, the cluster or other programs that write to the
data directory must not be started or else data loss may occur.
When using a replication setup with tools which perform direct copies
of relation file blocks (for example pg_rewind(1)), enabling or
disabling checksums can lead to page corruptions in the shape of
incorrect checksums if the operation is not done consistently across
all nodes. When enabling or disabling checksums in a replication setup,
it is thus recommended to stop all the clusters before switching them
all consistently. Destroying all standbys, performing the operation on
the primary and finally recreating the standbys from scratch is also
safe.
If pg_checksums is aborted or killed while enabling or disabling
checksums, the cluster's data checksum configuration remains unchanged,
and pg_checksums can be re-run to perform the same operation.
PostgreSQL 17.4 2025 pg_checksums(1)
postgresql 17.4 - Generated Sat Mar 22 11:39:43 CDT 2025