Professional SQL Server™ Analysis Services 2005 with MDX

7.1. Calculation Fundamentals

At the core of the Analysis Services engine is the ability to model various complex business problems using calculations. In Analysis Services 2000, calculations were based on dimensions such that each dimension typically contained one or more multilevel hierarchies. The calculation model of Analysis Services 2005 differs from the previous version because it combines the traditional OLAP and relational worlds. That combination occurs by leveraging the Unified Dimensional Model through attribute hierarchies (which are entities within a dimension). The attributes and the relationships between the attributes form the basis of the calculation model. The hierarchies (attribute or multilevel) are a way of navigating the dimensional space. Attribute hierarchies typically have two levels, the optional "All" level and another level that contains all the members of the attributes. Hence cells in the cube space can be accessed directly through the attribute hierarchies or multilevel hierarchies, and you will get the same results. Most of the calculation definitions for a cube are defined within an entity called MDX Script, which is part of every cube object. Some calculations are specified as properties of dimension attributes. Even while defining security for various hierarchies within a dimension, you specify the security restrictions through the attribute hierarchies of the dimension. Hence, attributes form the fundamental building blocks for all calculations ...