1. Database evolution

Before giving a technical definition of distributed databases, we'd like to explain how they fit into a company's information systems.

An information system is a set of resources and processes used to process information for decision-making purposes. More precisely, an information system is made up of :

• a database (in the broadest sense of the term, i.e. classic files or databases), the organization's real memory, since it contains information about the company's staff, products and customers;

• a set of processes (and therefore human or automatic processors) capable of processing this data.

The essential role of an information system is to "steer" the company by providing decision-makers (directors, managers, etc.) with reliable, synthetic data on...