I have to agree with the last sentiment. In my experience, one never ends up having all of one's update/migration (to a new version) changes constrained only t

I have to agree with the last sentiment. In my experience, one never ends up having all of one's update/migration (to a new version) changes constrained only to schema alterations. This is because the static database structure can only capture so much metadata. One inevitably ends up facing putting migration logic into the application itself, or logic that says "if old data, treat differently." So now one ends up with a mixed data migration situation: both database-level and application-level. Thus, it's a quite valid, pragmatic tradeoff to make: handle all data migration/schema changes in the application, let the store be completely dynamic and have it all in one level.