RE: Resetting recovery target parameters in pg_createsubscriber

Hayato Kuroda (Fujitsu) <kuroda.hayato@fujitsu.com>

From: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>

To: 'D Laaren' <dlaaren8@gmail.com>

Cc: "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>

Date: 2025-09-01T02:06:34Z

Lists: pgsql-hackers

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

pg_createsubscriber: Improve handling of automated recovery configuration
- 639352d904c8 19 (unreleased) landed

Dear Laaren,

> I noticed that pg_createsubscriber sets recovery target params for
> correct recovery before converting a physical replica to a logical
> one but does not reset them afterward. It can lead to recovery
> failures in certain scenarios.
> For example, if recovery begins from a checkpoint where no WAL records
> need to be applied, the system might incorrectly determine that the
> recovery target was never reached because these parameters remain
> active.

Thanks for reporting.
I have known that parameters won't be overwritten, but I didn't recognize the
case that recovery fails.

> I’ve attached a TAP test to reproduce the issue.
> The proposed patch ensures all recovery parameters are reset after
> conversion to prevent such edge cases.

WriteRecoveryConfig() has been used to setup the recovery parameters. Can we
follow the way to restore them?

Also, can we add a test to 040_pg_createsubscriber? IIUC it is enough to check
one of recovery parameter is reset after the conversion.

Best regards,
Hayato Kuroda
FUJITSU LIMITED