A common approach in designing relational databases is to start with a universal relation schema, which is then decomposed into multiple subschemas. A good choice of subschemas can be determined using integrity constraints defined on the schema, such as functional, multivalued or join dependencies. In this paper we propose and analyze a new normal form based on the idea of minimizing overall storage space and update costs, and as a consequence redundancy as well. This is in contrast to existing normal forms such as BCNF, 4NF or KCNF, which only characterize the absence of redundancy (and thus space and update time minimality) for a single schema. We show that our new normal form naturally extendexisting normal forms to multiple schemas, and provide an algorithm for computing decompositions.

database design, universal relation, dependencies, normal form