A data warehouse is a logical collection of information—gathered from many different operational databases—used to create business intelligence that supports business analysis activities and decision-making tasks (see Figure

1). Sounds simple enough on the surface, but data warehouses represent a fundamentally different way of thinking about organizing and managing information in an organization.

Figure 1

Consider these key features of a data warehouse, detailed in the sections that follow.

DATA WAREHOUSES ARE MULTIDIMENSIONAL

In the relational database model, information is represented in a series of two dimensional files or tables. Not so in a data warehouse—most data warehouses are multidimensional, meaning that they contain layers of columns and rows. For this reason, most data warehouses are really multidimensional databases. The layers in a data warehouse represent information according to different dimensions. This multidimensional representation of information is referred to as a hypercube.