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pg_checksums

pg_checksums — enable, disable or check data checksums in a PostgreSQL database cluster

Reading PostgreSQL 18.6.

Description

pg_checksums — enable, disable or check data checksums in a PostgreSQL database cluster

Documented executable: pg_checksums
Executable version: 18.6
Reference inventory: Server applications
Option definition groups: 11

Usage

pg_checksums [ option ...] [[ -D | --pgdata ] datadir ]

Documented options

Option and arguments	Description
-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.
-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 variables

Variable	Meaning
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 .

Manual definition

pg_checksums

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), 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.

Documentation and source

Source build

Version: 18.6
Build: https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2
Source fingerprint: ee8d1a3612338fd9adf250730cb640fcc5233b5491337cc00a316a44e3a0b9f8

Compare versions

PostgreSQL 16 → 17: changed.

--- PostgreSQL 16
+++ PostgreSQL 17
@@ -67,6 +67,13 @@
       "signature": "-P --progress"
     },
     {
+      "description": "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.",
+      "names": [
+        "--sync-method= method"
+      ],
+      "signature": "--sync-method= method"
+    },
+    {
       "description": "Enable verbose output. Lists all checked files.",
       "names": [
         "-v",

Compares recorded interfaces and attributes. Source fingerprints and build metadata are excluded; an absent sample is not proof of the introduction or removal release.

Related entries

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