What are multidimensional cubes?

A cube in a multidimensional data source has the following components:

• A measure, which is the name given to the data itself; that is, to the data that you track such as sales figures or cost numbers.

• One or more dimensions. Dimension is the name given to the parts of the cube that categorize the data, such as Product, Geography, and Time. Dimensions have dimension members, dimension hierarchies, and attributes.

For example, Figure 3-3 shows a cube that contains sales figures for different products in different years and in different cities:

• The sales figures are the data in the cells of the cube. Sales is the measure for this cube.

• The parts of the cube that categorize the data are Product, Time, and City. Product, Time, and City are the dimensions of this cube.

Figure 3-3 Cube of Sales data

Description of the illustration cube1.gif

The cube contains a measure value for each possible combination of the different dimensions. It is therefore very quick for applications such as Discoverer Plus OLAP to find the value for sales of a particular product in a particular city in a particular year. For example, to find sales of Product C in 2003 in Dallas, Discoverer Plus OLAP simply uses the Product, Time, and City dimensions to identify the cell that contains the required value, as shown in Figure 3-4.

Figure 3-4 One measure value in a cube

Description of the illustration cube2.gif