data_checksums

data_checksums — Shows whether data checksums are turned on for this cluster. Observed in PG9.3–19 Beta 3; its last measured boot default is off in PG19 Beta 3, with internal context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA.

Note

Fact — official short description: “Shows whether data checksums are turned on for this cluster.”

Identity

Type , Valueenum: Upstream pg_settings type
Context , Valueinternal: Internal/preset and not user-settable
Unit , Value—: Raw unit
Range , Value—: Raw limits in the last observed version
Enum values , Value"": — for non-enum types
Category , ValuePreset Options: Upstream classification
Latest boot value , Valueoff: off

Lifecycle

Fact	Value
First observed	PG9.3
Present in	PG9.3–19 Beta 3
Removed in	No
Introduction commit	`5a7e75849cb5` — Add a GUC to report whether data page checksums are enabled.
Commit date	2013-09-16
Discussion	—

Default history

Measured PG9.0–19 Beta 3 boot defaults
Versions	Raw `boot_val`	Unit	Human value
PG9.3–19 Beta 3	`off`	—	off

How it works

Reports the cluster-wide data-checksum state stored in the control file. It is internal/read-only in SQL and cannot be changed with SET.

Checksums are chosen by initdb or changed later with the server stopped by pg_checksums. PostgreSQL verifies page checksums when reading from storage and computes them when writing pages.

A checksum detects a torn or corrupted page; it does not repair it or prove that WAL, backups, memory, and every storage layer are healthy. Changes require an offline procedure, capacity for a full-cluster scan, and a verified backup.

Tuning advice

Tip

Advice. These are workload-specific starting points and must be validated with measurements.

Workload	Guidance
OLTP	Treat the value as an integrity capability, not a performance knob. Prefer checksums for persistent clusters and monitor checksum failures; use a planned offline pg_checksums procedure for an existing cluster.
OLAP	Budget the checksum CPU and full-cluster enable/disable scan on the actual dataset. Verify backup and replica compatibility before the offline transition.
Small nodes	Enable at initdb when possible. For an existing small cluster, pg_checksums is usually simpler than a rebuild, but still requires shutdown and a recoverable backup.

Pigsty

Values use the fixed 8-vCPU, 32-GiB, 100-GiB SSD fixture and render the current Pigsty templates for PG19 Beta 3; this does not assert current Pigsty support for that historical or beta release.

Template	Effective value	Versus upstream boot	Source expression
OLTP	Unmodified	—	—
OLAP	Unmodified	—	—
CRIT	Unmodified	—	—
TINY	Unmodified	—	—

Caution

Advice — pending human review. Fact from the current Pigsty template projection: OLTP: PG9.3–19 Beta 3 unmodified; OLAP: PG9.3–19 Beta 3 unmodified; CRIT: PG9.3–19 Beta 3 unmodified; TINY: PG9.3–19 Beta 3 unmodified. No Pigsty-specific rationale is inferred from an absent override.

Common pitfalls

Trying to change the read-only report with SET or ALTER SYSTEM.
Running pg_checksums while the server is not cleanly shut down.
Treating a checksum failure as repairable by ignoring the error.
Assuming checksums validate WAL records, logical correctness, or backups by themselves.
Enabling checksums without monitoring checksum failures and storage health.

ignore_checksum_failure · zero_damaged_pages · wal_log_hints · full_page_writes · data_directory · block_size