Reporting Services-generate MDX, Subselects and Formula Caching

Analysis Services can, of course, cache the results of MDX calculations and share that cache with other users most of the time... but when it can't the result is much unnecessary load on your server as calculations are recomputed again and again, and much longer query times. Unfortunately the details on what caching AS can do when are not properly documented anywhere and I've only learned the bits and pieces that I know about this subject from my own experience and from talking to the likes of Mosha; I've avoided blogging about it because my knowledge is incomplete and this is a complex topic. Happily the upcoming AS2008 Performance Guide should rectify this lack of proper documentation, and I believe Mosha is also going to address this subject in his pre-conf seminar at PASS.