Aspects of the design of distributed databases

Distributed data - data, processed by a system, can be distributed among several computers, but it is accessible from any of them. A distributed database design problem is presented that involves the development of a global model, a fragmentation, and a data allocation. The student is given a conceptual entity-relationship model for the database and a description of the transactions and a generic network environment. A stepwise solution approach to this problem is shown, based on mean value assumptions about workload and service. A management system of a distributed database (SGBDD) is a software system that enables management and distributing BDD transparent to the user. A SGBDD consists of a single database which is decomposed into fragments, poassibly some fragments are multiplied, and each fragment or copy kept on one or more sites under the control of a local DBMS. Each site is capable of processing user queries in the local system, independently of the rest of the network, or is able to participate in the processing of data in other sites in the network. To say that a DBMS is distributed CLE should be less global demand.