| pg_checksums(1) - phpMan
PG_CHECKSUMS(1) PostgreSQL 12.3 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,
every file in the cluster is rewritten. 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.
-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 12.3 2020 PG_CHECKSUMS(1)
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