A Dimension is the list of elements of a given variable which will be graphically represented or analyzed through the creation of a multidimensional model.
For example: products, zones, and dates are a few typical dimensions of a Sales model.
Each model includes the dimensions the designer deems appropriate, considering the model's objective. Therefore, it is important to consider that the analysis capabilities a user can achieve with a given model are restricted to the dimensions included in the model's definition.
The vast majority of the dimensions through which we can express reality arrange their elements in a hierarchical way. This means that there are relationships between them that "subordinate" the elements of a level to their correspondents in the immediate upper level of the hierarchy.
This hierarchical organization is viewed as a tree, with a principal branch representing the highest level of the hierarchy. That branch subdivides into smaller branches until reaching the leaves, which represent the lowest level of the hierarchy and have no subordinate elements.
For example, in a company, you can group salespeople by the zones in which they work. You can group the zones into areas, the areas into cities, and the cities according to the country they belong to.
Another example is the case of expenses sections for a given company. You can organize them into Departments, which are grouped into Divisions that can even belong to different companies.
Therefore, a "level" is each one of the "layers" of the hierarchy. For example, the salespersons are the lowest layer, followed by the zones, areas, cities, and finally the countries, which are the highest level of the hierarchy.
Hierarchies play a very important role in the analysis process, as they allow the analysis to take place at different levels of detail for each dimension. The hierarchical structure of the Date Dimension, for example, allows the end-user to begin analysis with an annual vision, and then obtain more detailed data on the level of quarters, months, or even weeks, through Drill-downs; that is, through "navigational" operations.
O3 automatically manages the summaries necessary for this type of analysis. That is, O3 automatically calculates the necessary aggregations to obtain consolidated data for the superior levels from the data obtained in the sources in the minimum level of detail. With the hierarchies definition in O3, the designer of the model indicates which aggregation levels are relevant for each particular case.
In addition to the election of the dimensions to be included in the model, the building of the hierarchies determines, a priori, the analysis possibilities with respect to the level of detail the end user will be able to reach with the Cubes created from the model.
The dimensions of a model are identified in the Design Tree, through the Dimensions branch. The nodes corresponding to each one of the dimensions are located within the Dimensions branch.
To configure dimensions, you must be in the Design Tree at Dimensions branch on the node corresponding to the dimension you are configuring. Access the properties of the dimension configuration through the Properties pane display on the right side of the screen.