When a user drills up, Discoverer leaves the original item in situ, adds the drilled-up item to the query to the right of the original item, and leaves the number of rows the same.
When a user drills down, Discoverer removes the original item, replaces it with the drilled-down item, and increases the number of rows to accommodate the new situation.
Because a picture tells a thousand words, allow me to explain the above scenarios using sme images from my own system. First of all, I must have a start point. I will then take this base worksheet and first of all drill up from the quarter to the year, followed by drilling down from the quarter to the month:
The base worksheet:
Note: for this demonstration, the fiscal year runs from October 1 to September 30.
Let's drill UP. When drilling up, the new item is added to the query rather than replacing the original, thus retaining the same number of rows. Interestingly the new (aka summary) drilled-to item is added to the right of the original item rather than to the left which is where it should be. This is all standard Discoverer functionality so please don't shoot the messenger. Personally, I think it would be better if Discoverer were to replace the original item with the drilled-up item and reduce the number of rows to summarize the data. Unfortunately, as you can see below, it does not:
The drilled-up worksheet:
Let's drill DOWN. When drilling down, the new item replaces the original item and Discoverer increases the number of rows to accommodate the new situation. In my opinion, this is also incorrect. I think it would have been better if Discoverer had retained the original item and added the drilled-down item to its right-hand side. This way I could easily add a group sort on the higher-level item with a sub-total on each break.
Here is Discoverer's method of drilling down:
The drilled-down worksheet:
Of course, I know you can always edit the worksheet and add back in the item that was removed, which is exactly what I did above.