Types of Databases

Database Systems Design, Implementation, and Management, 6e
Chapter 1: Database Systems

ISBN: 061921323X Author: Peter Rob, Carlos M. Coronel
copyright © 2005 Course Technology

1.2.1 Types of Databases

A DBMS can support many different types of databases. Databases can be classified according to the number of users, the database site location(s), and the expected type and extent of use.

The number of users determines whether the database is classified as single-user or multiuser. A single-user database supports only one user at a time. In other words, if user A is using the database, users B and C must wait until user A has completed his/her database work. If a single-user database runs on a personal computer, it is also called a desktop database. In contrast, a multiuser database supports multiple users at the same time. If the multiuser database supports a relatively small number of users (usually fewer than 50) or a specific department within an organization, it is called a workgroup database. If the database is used by the entire organization and supports many users (more than 50, usually hundreds) across many departments, the database is known as an enterprise database.

The database site location might also be used to classify the database. For example, a database that supports data located at a single site is called a centralized database. A database that supports data distributed across several different sites is called a distributed database. The extent to which a database can be distributed and the way in which such distribution is managed is addressed in detail in Chapter 10, “Distributed Database Management Systems.”

The most popular way of classifying databases today, however, is based on how they will be used, and on the time sensitivity of the information gathered from them. For example, transactions such as product or service sales, payments, and supply purchases reflect critical day-to-day operations. Such transactions are time-critical and must be recorded accurately and immediately. A database that is primarily designed to support a company’s day-to-day operations is classified as a transactional database or a production database. In contrast, a data warehouse database focuses primarily on the storage of data used to generate information required to make tactical or strategic decisions. Such decisions typically require extensive “data massaging” (data manipulation) to extract information from historical data to formulate pricing decisions, sales forecasts, market positioning, and so on. Because most decision support information is based on historical data, the time factor is not likely to be as critical as for transactional databases. Additionally, the data warehouse database can store complex data derived from many sources. To make it easier to retrieve such complex data, the data warehouse database structure is quite different from that of a transaction-oriented database. We cover the design, implementation, and use of data warehouse databases and their “offspring” in detail in Chapter 12, “The Data Warehouse.”

Most of the database design, implementation, and management issues addressed in this book are based on production (transaction) databases. Our focus on production databases is based on two considerations. First, they are the databases you most frequently encounter in common activities such as enrolling in a class, registering your car, buying a product, or making a bank deposit or withdrawal. Second, data warehouse databases derive most of their data from production databases, and if production databases are poorly designed, the data warehouse databases based on them will lose their reliability and value as well.

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