Containment and disjointedness in partitioned normal form relations

Abstract.

Containment and disjointedness are two important properties in the updating materialized views. Disjointedness means that the set of tuples to be inserted in the view are disjoint from the view, and containment means that the tuples to be deleted from the view are contained in the view. In this paper we consider how to extend the definition of containment and disjointedness from flat relations to nested relations which are in partitioned normal form. The two correctness requirements that we place on our definitions are that they must be faithful and precise; where faithful means that the definition should coincide with the corresponding definition for flat relations when the nested relations are flat, and precise means that the definition should coincide with the corresponding definition for flat relations after performing a total unnest on the nested relation. We then propose definitions for disjointedness and containment for partitioned normal form relations and prove that the definitions proposed are faithful and precise. We also show that simple set based extensions of the definitions for flat relations are not correct since they are not precise.