A uniform view mechanism for the TIGUKAT objectbase

Abstract

Object-Oriented database systems (OODBs) are emerging as the most likely candidate to meet data management requirements of new complex applications. Object-Oriented views have been recognized as a powerful mechanism for customizing the structural as well as behavioral aspects of OODBs interfaces for diverse user needs. They are used to provide data independence, authorization enforcement, integration of heterogeneous and distributed systems and efficient update mechanisms. In this thesis, a uniform capacity-augmenting view mechanism for the TIGUKAT object model is presented. Following the uniform semantics of the TIGUKAT object model, two new types, T-virtualtype and T-view, are added into the primitive type system and the behaviors defined on them are given. The capacity-augmenting virtual type, T-virtualtype, can restructure base types and augment the storage capacity of base types by incorporating additional behaviors. A view is defined as a user-selected subschema of the global schema with internal and external aspects. We extend the TIGUKAT defini ion language and query language to define virtual types and view schema. To integrate virtual types into a consistent type lattice, a type integration algorithm based on the TIGUKAT axiomatic model of dynamic schema evolution is developed.