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PostgreSQL 19 lets you enable or disable data checksums on a running cluster, without a restart or reinitialization. That capability is part of a PostgreSQL 19 beta, so treat the details below as provisional until the final release documentation is published.
What PostgreSQL 19 changes
The PostgreSQL 19 Beta 1 announcement states that data checksums can be enabled or disabled online, without requiring a cluster restart or reinitialization. The official commit announcement by Daniel Gustafsson, dated 2026-04-03, puts the same capability in terms of access: “This allows data checksums to be enabled, or disabled, in a running cluster without restricting access to the cluster during processing.”
The phrase that matters is “without restricting access.” Enabling checksums is no longer something you do only by taking the cluster down. The commit text describes the change as processing in a running cluster, and it does not promise that the operation is instantaneous or free of load. No processing times or performance figures were published with the announcements reviewed, so you should not assume either.
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One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchRelease status: The official PostgreSQL 19 release documentation page reviewed in October 2026 showed a Beta 4 announcement dated September 24, 2026, and listed the final release date as unknown. Until a final release is published, this is a beta feature whose interface and caveats may still change.
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The offline workflow it does not replace
Before this change, the documented way to turn checksums on for an existing cluster was the pg_checksums utility. It works on a cluster that has been shut down cleanly. While enabling checksums, it rewrites the blocks of relation files, and the manual warns that the cluster and any other program writing to the data directory must not be started during the operation.
Because of that offline requirement, pg_checksums should not be described as the online control. The online capability in PostgreSQL 19 is a separate mechanism, and the announcements do not say that pg_checksums has changed to match it.
Offline versus online at a glance
| Comparison point | pg_checksums (documented offline utility) |
PostgreSQL 19 online enablement (beta) |
|---|---|---|
| Required operating state | Cluster must be shut down cleanly | Cluster is running |
| Access during the operation | No server or writing programs may run against the data directory | Access is not restricted during processing, according to the official commit announcement |
| What gets rewritten | Relation-file blocks | Not stated in the announcements reviewed |
| Published processing time or performance impact | Not stated in the manual reviewed | Not stated in the announcements reviewed |
| Availability | Established, documented PostgreSQL utility | PostgreSQL 19 beta; final release date not yet published |
What checksums protect
When data checksums are enabled, the checksum on a data page is updated when the page is written and verified when it is read. That is the full scope of the protection. The PostgreSQL documentation states that checksums cover data pages only, not internal data structures or temporary files.
Checksums are also a cluster-wide setting. You cannot turn them on for one database or one table while leaving the rest of the cluster unchecked.
How to check the current state
You can read the checksum state from any session connected to the cluster:
- Connect with
psqlto the cluster you want to inspect. - Run
SHOW data_checksums; - Read the result. The
data_checksumssetting is read-only and is a boolean that reports whether checksums are enabled for the cluster, so the value isonoroff.
The setting shows the cluster’s state. It does not tell you whether an enablement or disablement operation is still in progress, so check the server logs and the final documentation before assuming a change has completed.
Before you rely on this in production
- Confirm the release. Wait for the final PostgreSQL 19 release notes and the final version of the data-checksum documentation. The SQL and utility interface for changing the state should be confirmed there, because beta-era documentation can change.
- Check your provider. The announcements reviewed do not say whether managed PostgreSQL services expose this online control to their customers. Confirm with your provider’s own documentation before planning around it.
- Rehearse on a copy. No processing times, load measurements or performance figures were published with the announcements reviewed. Run the operation against a restored copy of a representative database and measure the effect before doing it on production.
- Keep the offline option in mind. If your version of PostgreSQL does not include the online capability, the documented
pg_checksumsroute with a clean shutdown remains the established method.
The Bottom Line
PostgreSQL 19 beta adds online enablement and disablement of data checksums without a restart or reinitialization, and the official commit describes access as not restricted during processing. Treat it as a beta capability: confirm the final release, the exact interface, and provider support before relying on it, and rehearse the change on a copy of your data first.
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