On bi-level conceptual schemas

The advent of Entity-Relationship (E-R) model has revolutionized the database design process. The overwhelming success of Entity-Relationship approach to database design partly lies in the simplicity and semantic clarity of the E-R model. However, two seemingly conflicting measurements of database design: logical-clarity and physical-efficiency, force database designers to choose either logically-clear design or physically-efficient design. As a result, the resulting design is either logically-clear or physically-efficient, but not both. This paper is to provide a remedy for this situation. In this paper, we first discuss the concept of logical-clarity and physical-efficiency of logical database design. Then the concept of bi-level conceptual schema is introduced. The bi-level conceptual schema concept allows us to create a logical database design that is both logically-clear and physically-efficient. Finally, a database management system prototype (DBMSB) that supports bi-level conceptual schema is described.