If you can insert into either before/after versions of the schema, I feel like it’d be possible to reach an irreconcilable state; eg if you add a unique constra

If you can insert into either before/after versions of the schema, I feel like it’d be possible to reach an irreconcilable state; eg if you add a unique constraint to your schema, but the app is inserting into the pre-constraint version of the schema, there’s no way to roll forward. Unless you have a migration script to specify the roll-forward logic, but then you’re just back to the same problem you have today. Immutable data I understand under a static schema, but I can’t imagine there’s a way to make immutable data under a dynamic schema sane