Two or three views on database views

Bob Rosebrugh – 22 August 2007

Views are important in information system design and management. The view update problem: `when can a change in a view state be extended to the total database state?' has been much studied. An early approach treated states as unstructured sets and advocated views with `constant complement', although `constant factor' would have been a better name. Recently the `lens' concept and a simple monad have elucidated the situation. A more recent order-based approach with an ordered set of states provides a generalization though still requiring complements. When states are a category of models, a less narrow view of updatability emerges. This is joint work with Michael Johnson and Richard Wood