Avoid redundant attribute relationships because these relationships may prevent data from being aggregated when the granularity attribute of a cube is a non-key attribute
This rule analyzes dimensions to determine whether they contain redundant attribute relationships.
Do not create redundant attribute relationships. Redundant attribute relationships are attribute relationships that are transitively implied by other attribute relationships. In other words, more than one logically equivalent path exists between attributes. For example, if the relationships A->B, B->C, and A->C have been created, A->C is redundant and should be removed.
Redundant attribute relationships could lead to incorrect aggregation of data because the server picks a single path along which to aggregate. The path picked by the server is typically the shortest path. (In the example discussed in the previous paragraph, the server will pick the path A->C.) However, the longer path is better because it adds more information. (In the example discussed in the previous paragraph, the longer path would be A->B and then B->C.) In addition to being more expressive, relationships higher in the attribute tree provide more efficient storage and memory use because the related attribute must typically be associated to fewer members.