Database Constraint Enforcement: A Decompositional Approach.

This thesis presents an efficient and integrated approach to integrity constraint checking for advanced database systems. The proposed approach essentially consists of three phases: constraint decomposition, global enforcement strategy and local enforcement tuning. The central theme of this dissertation is the development of constraint decomposition theory, which can be used to decompose each constraint formula into a set of constraint sub-formulas. The constraint sub-formulas derived from the decomposition satisfy the sufficient conditions imposed by the original constraint and are also much simpler and more efficient to check. The decomposition is done only once for each constraint, at the time of its definition. The global enforcement strategies, with the application of decomposition theory, are studied in both sequential and parallel environments. The physical characteristics of the database state is used to determine the checking order or to make assignment of constraint sub-formulas to processing elements. It is shown that the performance of constraint enforcement, with the application of the decomposition theory, is much better than that without the application of the decomposition theory. Local enforcement tuning methods are developed to further simplify each constraint sub-formula derived at constraint decomposition phase. Because of the simplicity of constraint sub-formulas, more efficient and simple methods can be used. Furthermore, more information, such as update types and update data, are available for the purpose of simplification. The fundamental assumption underlying our approach is that most database updates satisfy integrity constaints. A second assumption is that transactions are localized and database updates are nonuniform in their distribution. Based on these assumptions, the proposed approach will achieve a significant performance increase over previous approaches

Economic data bank management in a developing nation

This dissertation describes the results of a research project which was undertaken at Loughborough University of Technology. The basic objectives of the research project were: (1) to investigate the management elements required for organising the development of an Economic Data Bank (EDB), with particular emphasis on the requirements of a developing nation; (2) to investigate the sociological, political and technical implications associated with organising the development of an EDB in a developing nation. A theoretical framework was established for this study. This was dene after an extensive search and review of literature was performed in the areas of data and data base management systems, management information systems, and computer technology in general. [Continues.