[JackFr]

> A "big bang" migration makes more sense, if everything is properly prepared and tested, which it wasn't.

That sounds like ‘A “big bang” migration makes more sense, if it works.’

Your rollback plan should never be an afterthought. Your rollback plan should be designed like you expect to use it. If your rollback plan is “Burn the ships” and fix-forward, you shouldn’t be working at a bank.

[flerchin]

Definitely been the plan at a variety of places I've worked. Including a bank.