Long Navigation Parameters
I was shocked recently when my nice report that was executing in 2 seconds suddenly took 22 seconds to finish after I enabled navigation (i.e. drillthrough links) in every textbox in the report. The point of this post is to explain what’s going on and suggest workarounds to improve performance.
This particular report was an MDX report in Reporting Services 2005. If your MDX reports are anything like mine, you end up having an obscene number of multi-select parameters to give the end user maximum flexibility. This report was no exception. In SQL reports, the parameter values are often integers. However, in MDX reports, the parameter values are usually MDX unique member names such as [Product].[Category].&[Bikes]. You can already see the problem. If you have many large multi-select parameters, the concatenated list of selected parameter values becomes large. In fact, for this report, that list ended up being about 30KB long. Multiply that times 3,000 textboxes in the report, and your speedy report is now a 90MB beast.