This paper describes a simulation study of the effect of runtime schema interpretation in a network data model database management system. To perform database operations, programmers use a data manipulation language which supports calls to the data manipulation routines. The data manipulation routines utilize database descriptors from the schema to determine which operations on the database are to be performed for a given actual parameter to the procedure. Current database systems perform the binding of schema descriptors in the data manipulation routines at run-time by interpretation. A niumber of researchers are studying methods to precompute the information required to determine the correct function to execute rather than using run-time interpretation.

This paper examines object-oriented programming as an implementation technique for database systems. The object-oriented approach encapsulates the representations of database entities and relationships with the procedures that manipulate them. To achieve this, we first define abstractions of the modeling constructs of the data model that describe their common properties and behavior. Then we represent the entity types and relationship types in the conceptual schema and the internal schema by objects that are instances of these abstractions. The generic procedures (data manipulation routines) that comprise the user interface can now be implemented as calls to the procedures associated with these objects. A generic procedure model of database implementation techniques is presented and discussed. Several current database system implementation techniques are illustrated as examples of this model, followed by a critical analysis of our implementation technique based on the use of objects. We demonstrate that the object-oriented approach has advantages of data independence, run-time efficiency due to eliminating access to system descriptors, and support for low-level views.