[onion2k]

The difference is largely semantic in the sense that you're still going "forwards" with a down migration, but the important bit is that by calling it a rollback you're accepting that the up migration won't be run again if you ever completely tear down the database and start again. Suggesting that you only ever go forwards implies that you'd run the incorrect migration and the fix for it again in the future,but you wouldn't. Calling it a rollback captures that information.

[hellcow]

It's not a semantic difference. If you rollback, that's not in the history. That's fine if the rollback perfectly reversed your original migration. But if it doesn't (developers make mistakes), now your database has reached a state that can't be reproduced by running migrations, defeating the entire point.

> Suggesting that you only ever go forwards implies that you'd run the incorrect migration and the fix for it again in the future,but you wouldn't.

I wrote a tool that specifically enforces this for my company, and it's worked well for the past four years in prod, staging and on a dozen dev environments, so I don't think your assertion is true.