13 DISTRIBUTED DATA AND DATABASES
This chapter looks at some of the issues that need to be addressed when distributing data. Unfortunately all of the theory is based on the distributing of a single set of data – the top-down approach – to improve reliability and availability, but the more likely scenario these days is where an organisation wishes to integrate its disparate systems so that it looks to the users as if there is a single set of data – the bottom-up approach.
THE RATIONALE FOR DISTRIBUTING DATA
Our discussion of database architecture in Chapter 2, and particularly the three-level schema architecture, was based on the assumption that all the data would be held in a single database at a single site. Such an arrangement is the logical ...