DISTRIBUTED DATABASES ON LOCAL MULTIACCESS COMPUTER SYSTEMS (QUERY PROCESSING, FILE ALLOCATION, CONCURRENCY CONTROL)
Abstract
Concurrency control, distribution design, and query processing are key issues in the design of distributed databases. In this research, we have studied these issues with respect to a relational database on a local computer system connected by a multiaccess broadcast bus. A broadcast bus not only allows information to be distributed efficiently but also provides a synchronization tool for the concurrency control. Consequently, it simplifies the distributed database design. Some NP-hard file placement problems are found to be solvable in polynomial time when updates are broadcast. A transaction model that integrates the concurrency control and query processing is proposed. In concurrency control, a protocol based on locking is used since much less communication overhead is needed for lock management. A dynamic strategy is used in query processing, as less data are transferred when compared to a static strategy. The status information needed in dynamic query processing can be conveniently obtained by broadcasting. Lastly, a new query processing strategy is proposed for the distributed database connected by the fast communication networks. The problem is formulated as a generalized traveling salesman problem, and is solved by various solution algorithms. The performance of the system is evaluated by simulations on a SUN workstation. The results shows the design is feasible and efficient.
Degree
Ph.D.
Subject Area
Electrical engineering
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