What are the best practices redarding rollbacks when the database is affected. I would think a large amount of overhead would be required.
Rainforest QA had a blog post on strategies a while ago.
One could imagine a test rig which created a db with test users in it, then ran v1 of the software, then v2, then v1 again, and checked v1 didn't crash on the now mutated datastructures.
Most datastore mutations might only happen on certain user actions and inputs, so making sure you get full coverage would be rather tricky.
I like that -- reminds me of aviation, where a go-around is normal. If your approach to landing isn't stabilized, you're too high, too low, too fast, too slow, etc. don't try to save it. Go around and try again.
Next we plan to automate the process - 1 in 10 rollouts will actually be a rollout, a rollback, and another rollout, checking system health at each step.