Oracle Distributed Systems

Chapter 1. Introduction to Distributed Systems

Any organization that uses the Oracle relational database management system (RDBMS) probably has multiple databases. There are a variety of reasons why you might use more than a single database in a distributed database system:

• Different databases may be associated with particular business functions, such as manufacturing or human resources.

• Databases may be aligned with geographic boundaries, such as a behemoth database at a headquarters site and smaller databases at regional offices.

• Two different databases may be required to access the same data in different ways, such as an order entry database whose transactions are aggregated and analyzed in a data warehouse.

• A busy Internet commerce site may create multiple copies of the same database to attain horizontal scalability.

• A copy of a production database may be created to serve as a development test bed.

Sometimes the relationship between multiple databases is part of a well-planned architecture, in which distributed databases are designed and implemented as such from the beginning. In other cases, though, the relationship is unforeseen; it is quite common for distributed databases to evolve as businesses expand, requirements grow, and applications spawn. But common to all cases is the need to copy or reference data in one or more remote databases.

A distributed database system will meet one or more of the following objectives:

Availability

Data must be available at the local site even when ...