The following documentation comment has been logged on the website: Page: https://www.postgresql.org/docs/18/app-pgrewind.html Description:
Reference Page: https://www.postgresql.org/docs/current/app-pgrewind.html Proposed Enhancement: Include an explicit warning in the **"Description"** or **"Warnings"** section regarding the requirement for the target data directory to remain static during the rewind process. Reasoning: While the documentation states that `pg_rewind` "will fail immediately if it finds files it cannot write directly to," it does not currently warn against asynchronous file deletions within the target `$PGDATA` (or tablespace/WAL directories) while the utility is running. In high-concurrency or automated environments, background processes—such as the **WAL summarizer** cleanup, automated log rotations, or external archiver tools (e.g., `pgbackrest` spooling)—may remove files that `pg_rewind` has already indexed for synchronization. This results in a fatal "No such file or directory" error during the final stages of the rewind, often leaving the target directory in an unrecoverable state. Suggested Phrasing: "Warning: The target data directory must remain static during the rewind operation. Any asynchronous file modifications or deletions—such as those performed by automated log rotation, WAL summary cleanups, or external backup tools—may cause `pg_rewind` to fail. If a file is removed after the synchronization process has begun, the utility may error out, leaving the target cluster in an inconsistent state that requires a new base backup."
