> it is helpful to have a tracking of which schema is in the database and which > one is expected by the code.
[Norman](https://moigagoo.github.io/norman/norman.html) is a migration manager for Norm. It lets you apply and undo migrations, preserving order. I have to update it for Norm 2, possibly rewriting it since Norm has changed a lot. As of now, it just stores the name of the last applied migration in a file called `.last`. I'd rather store that information in the DB, but that requires more work. Also, I find your idea with hashes really interesting.
