Engineer at PlanetScale; If you drop columns that are `NOT NULL DEFAULT <something>`, and then you insert some new rows to your newly-versioned table, then you're in a good spot: when you revert, those columns will get the DEFAULT value on those rows.

If those columns were `NOT NULL` and with no DEFAULT, then you are unable to rewind. The rewind process will make an attempt -- after all, maybe you didn't add new rows; maybe you just deleted or updated -- but if you did INSERT new rows, then the Rewind process will fail (and you will be notified that rewind is impossible).

There's a couple more interesting scenarios, see this doc page for more: https://docs.planetscale.com/concepts/deploy-requests