Database Systems: Concepts, Design and Applications

18.1. Introduction

In the previous chapter we discussed parallel database architectures in which multiple CPUs are used in a closed vicinity (for instance, in a building). The processors (CPUs) are tightly coupled and constitute a single database system. In other architecture, multiple CPUs are loosely coupled and geographically distributed at several sites, may be in different buildings or cities, communicating relatively slowly by telephone lines, optical fibre networks or satellite networks, with no sharing of physical components. The databases operating in such environment is known as distributed databases. Distributed database technology has now become the reality due to the rapid development in recent times in the field of networking and ...