Everyone working with Business Intelligence must have heard of Mr Kimball. While reading newsletters from various BI sites I came across a interesting article from Kimball University. The article discuss how to handle an employee dimension so that hierarchies can be easily traversed when doing reporting and ad-hoc queries, while keeping query performance and enabling type 2 slowly chanching dimensions.
Since employee dimensions can be rather large it's also important that the amount of rows is kept to a minium.
Take a look at the article to get some inspiration on how to design the warehouse to efficiently handle complex hierarchies.