A database should have no more than 3 parent-child dimensions that have the UnaryOperatorColumns, CustomRollupColumns, or CustomRollupPropertiesColumns calculations defined on the attributes
This rule analyzes database dimensions to determine whether there are more than three dimensions that both contain parent-child hierarchies and include custom rollups, unary operators, or semi-additive measures.
Best Practices Recommendations
For best performance, you should typically minimize the use of parent-child dimensions that contain custom rollups, unary operators, or semi-additive measures.
Parent-child dimensions, especially those that contain custom rollups and unary operators, can sometimes be useful. However, to prevent poor query performance, such parent-child dimensions should only be used when necessary.
For More Information
For more information about how to define parent-child hierarchies, see Working with Attributes in Parent-Child Hierarchies in SQL Server Books Online.
For more information about performance issues related to dimensions that contain parent-child hierarchies, see the section, "Parent-child hierarchies," in the SQL Server 2005 Analysis Services Performance Guide.