Complex domain-specific requirements preclude simple joins unfortunately. This is why I'd like to redevelop these queries in C#. There are many imperative steps performed on each time series record to decide how these reports are generated.

To give a very broad example of one report: take 10,000 latest time series records from geographic location X. Now for each of those records load the latest 100 time series records from location Y and Z. Multiply all records from Y and Z together then divide by the value at location X. Throw in lots of business rules at every one of these steps so we have no chance of representing this as a tidy join operation and so that we can make no assumptions about the data we'll need to load to generate the report :)