This is correct if I understand you. Basically, when people add something new to a schema, they're generally tacitly also admitting it's optional. Optional fiel

This is correct if I understand you. Basically, when people add something new to a schema, they're generally tacitly also admitting it's optional. Optional fields should not exist on the same table as non-optional fields, because then you have to allow everything to be null or a specially designated value.