IIF Function Query Hints in SQL Server Analysis Services 2008

Thomas Kejser and I are doing some work to produce the SQL Server 2008 Analysis Services Performance Guide. Among a bunch of other things, it discusses the IIF function. But because I recently mentioned MDX query hints in a recent podcast, I wanted to get this out quickly. Some references are a bit hazy (expensive vs inexpensive query plans, default values and the like) and I’ll elaborate either in future blogs or in the white paper itself.

Anyway, the IIF mdx function is a commonly used expression that can be very costly to evaluate. It takes 3 arguments: