Re: Changing the state of data checksums in a running cluster

Tomas Vondra <tomas@vondra.me>

From: Tomas Vondra <tomas@vondra.me>

To: Daniel Gustafsson <daniel@yesql.se>, Bernd Helmle <mailings@oopsware.de>

Cc: Michael Paquier <michael@paquier.xyz>, Michael Banck <mbanck@gmx.net>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>

Date: 2025-08-20T17:02:57Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Use correct datatype for PID
- 0ca1b3010597 19 (unreleased) landed
Improve comments in online checksums code
- cd857dec0e0a 19 (unreleased) landed
Fix checksum state transition during promotion
- 5fee7cab1b87 19 (unreleased) landed
Fix regex searching for page verification failures in tests
- 486b9a9b9eb4 19 (unreleased) landed
Apply data-checksum worker throttling parameters
- 9a39056c418c 19 (unreleased) landed
Skip WAL for unlogged main fork during online checksum enable
- 2018bd616790 19 (unreleased) landed
Revert "Get rid of WALBufMappingLock"
- c13070a27b63 19 (unreleased) cited
Get rid of WALBufMappingLock
- bc22dc0e0ddc 18.0 cited
Improve grammar of options for command arrays in TAP tests
- ce1b0f9da03e 18.0 cited

Hi,

I think there's a minor issue in how pg_checksums validates state before
checking the data.

The current patch simply does:

  if (ControlFile->data_checksum_version == 0 &&
      mode == PG_MODE_CHECK)
      pg_fatal("data checksums are not enabled in cluster");

and that worked when the version was either 0 or 1. But now it can be
also 2 or 3, for inprogress-on / inprogress-off, and if the cluster gets
shut down at the right moment, that can end in the control file.

It doesn't make sense to verify checksums in such cluster, pg_checksums
should handle that as "off", i.e. error out.


regards

-- 
Tomas Vondra