Asymmetric Sets on Columns in Reporting Services
Now I don't know if I've blogged about this before - apologies if I have, but I can't find any trace of it on Google and since this is a fairly common performance-related problem it deserves to be mentioned. It's not rocket science MDX either but sometimes I think I focus too much on fun but obscure problems at the expense of real-world scenarios...
As you know, Reporting Services only allows you to have members from the Measures dimension on columns in a dataset. This is rubbish at the best of times since you need to use a matrix control to pivot your results, but it can sometimes present a performance problem.