they don't need to expand anything for you to have this functionality. You don't expose the schema where your tables live, you create a different schema (api) w

they don't need to expand anything for you to have this functionality. You don't expose the schema where your tables live, you create a different schema (api) where mirror views for those tables live. The second step is to add conditions on those views in such a way that when conceptually your client does "select * from A/B" he sees only the rows he is supposed to see and not all the rows.