ASSESSING THE TEMPORAL DIFFERENTIATION OF ATTRIBUTES AS AN IMPLEMENTATION STRATEGY FOR A TEMPORALLY ORIENTED RELATIONAL DBMS

Abstract

Temporally Oriented Databases (TODBs) are database systems in which both historical and current data are accessed and treated with full symmetry. The growing interest in such systems is manifested recently in a number of research efforts focusing on a wide set of issues, ranging from the study of abstract conceptual models to the practical implementation of working systems. Attempts to implement TODBs have so far been at best preliminary, characterized by an ad hoc flavor, or have had a very limited scope. This dissertation research is an attempt to design a general purpose relational Temporally-Oriented Database Management System (TDMS), and examine the feasibility of its implementation along current theoretical concepts. The users view data in a TDMS as a temporally oriented, three dimensional cube; this is, in fact, implemented as a two layered data structure. The implementation model interrelates the external user view with an underlying functional view of the data , and specifies on the translation between these layers. The major principle in the implementation is the differentiation of attributes according to their temporal variation . This research uses this concept as an implementation strategy of TDMSs, and assesses this approach for dealing with the following primary questions: efficient ways to store and retrieve data, the integrity constraints needed to maintain the database consistency and the definitions and implementations of temporal operations in such systems. Further validation of the model was achieved through the development of a TDMS prototype. The prototype was developed using INGRES commands embedded in PASCAL programs on VAX/VMS, and provides a test bed for further studies of temporally oriented information systems.