Calculated members vs assignments to real members
One design technique I see used quite frequently on my travels, usually in financial applications and usually by people who have experience with OLAP tools other than AS, is the creation of members on a dimension which have no real data associated with them in the fact table and whose value is later overwritten with an assignment in the MDX Script. Imagine the following scenario, for example: you have a chart of accounts dimension which has a member Total Sales, which represents the total sales of all of the operating units in your company; you also want another member, Sales Plus Tax, which is the Total Sales value multiplied by a constant representing the rate of tax. To implement this you could either create a calculated member on the Account dimension which did the calculation, or in your Account dimension table create an extra real member and then in the MDX Script use a scoped assignment to write the value of the calculation to that member.
Tags: mdx, performance