I can't see how this is simpler or more effective than having 5 state fields, each with a timestamp. I guess it would make writing the query slightly easier, bu

I can't see how this is simpler or more effective than having 5 state fields, each with a timestamp. I guess it would make writing the query slightly easier, but you can put your clause for any given state into a builder function anyway. What's the motivation for having an enum then holding in some other system a history of when that enum changed?