What are the components of a cube?

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

• A measure, which is the name given to the data itself.

• 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.

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.

What are measures?

In OLAP metadata, measures represent data that can be examined and analyzed in crosstabs and graphs. Examples include Sales, Cost, and Profit.

What are dimensions and dimension members?

Measures have dimensions that categorize the data in the measure. For example, a Sales measure might have Product, Time, and Geography as its dimensions. When a measure has a particular dimension, the measure is said to be dimensioned by that dimension. For example, Sales is dimensioned by Product. The group of dimensions for a measure constitute the dimensionality of that measure. For example, the dimensionality of Sales is Product, Time, and Geography.

Each element in a dimension is a dimension member. For example, January 2001, February 2001, March 2001, Quarter 1 2001, and the year 2001 are likely members of the Time dimension.

What are dimension hierarchies?

A dimension hierarchy describes a hierarchical relationship between two or more dimension members.

Individual dimension members might be related to each other in a hierarchical way. For example, a specific day belongs to a particular month, which in turn is within a particular year. To reflect such relationships, dimension members are organized into dimension hierarchies.

A dimension hierarchy is a logical structure that uses ordered levels as a means of organizing and aggregating data. For example, the Time dimension might have a hierarchy to aggregate data from the Month level to the Quarter level to the Year level.

A dimension can have more than one hierarchy. For example, as well as the Month-Quarter-Year dimension hierarchy, the Time dimension might also have a Day-Month-Year dimension hierarchy. Note that where multiple dimension hierarchies exist for the same dimension, one dimension hierarchy must be specified as the default hierarchy.

What are dimension attributes?

A dimension attribute describes a characteristic that is shared by dimension members. Dimension attributes enable you to select data based on similar characteristics. For example, a Product dimension might have a Color attribute that enables you to search for all red products.