Create hierarchies in non-parent child dimensions
This rule analyzes each database dimension to determine whether its attributes are organized into levels of a user hierarchy.
For best performance, you should typically organize attributes into a user hierarchy and then define attribute relationships between attributes that correspond to the levels in a user hierarchy. The data in most dimensions has some hierarchical structure that is worth exposing in the cube. Frequently, the Cube Wizard or Dimension Wizard will not detect this hierarchy. In these cases, you should manually define a user hierarchy. Only define relationships between attributes that have a one-to-many relationship. Organizing attributes into a user hierarchy also improves usability for most user scenarios. To increase usability even more, hide or rename the attribute hierarchies that are used as levels in the user hierarchy.
For more information about how to configure attributes and user hierarchies, see Defining and Configuring a User-Defined Hierarchy and Specifying Attribute Relationships Between Attributes in a User-Defined Hierarchy in SQL Server Books Online.
For performance issues related to attributes and user hierarchies, see the section, "Using hierarchies effectively," in the SQL Server 2005 Analysis Services Performance Guide.