Data management in distributed data bases*

The recent advances in large-scale integrated logic and memory technology, coupled with the explosion in size and complexity of the application areas, have led to the design of distributed architectures. Basically, a Distributed Computer System ( DCS ) is considered as an interconnection of digital systems called Processing Elements ( PEs ), each having certain processing capabilities and communicating with each other. This definition encompasses a wide range of configurations from an uniprocessor system with different functional units to multiplicity of general-purpose computers (e.g. ARPANET). In general, the notion of "distributed systems" varies in character and scope with different people. 30 So far, there is no accepted definition and basis for classifying these systems. In this paper, we limit our discussion to a class of DCSs which have an interconnection of dedicated/shared, programmable, functional PEs working on a set of jobs which may be related or unrelated.