As far as I understand WAL in PostgreSQL designed for control of the integrity of Database. On File System same purpose is served by CoW (Copy-on-Write) mechanism.

So WAL look like some overhead. So can it be safely turned off? After all, the integrity of data can provide the file system itself.

  • myself would accept a little overwhelming overhead but nevertheless getting corrupted data whoxh f... your brain and nerves
    – djdomi
    Commented Nov 9, 2021 at 17:35

1 Answer 1


Copy on write does not give you integrity of the filesystem. Assuming that you meant filesystem journalling, which does give you filesystem integrity, then you should almost certainly still use Write Ahead Logging.

Write Ahead Logging in PostgreSQL gives you database integrity at the transaction level, typically increases performance, as well as giving point in time backup and allowing online backups.

The documentation is pretty good at explaining this.

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