When I'm asked questions about SQL, I like Intersystems staff at the WRC, generally ask about the Query Plan. My feeling is that even before you run a query you should examine the results of Show Plan to confirm that the code is going to give me the results in the manner I would expect. If I expect it to leverage an index and I see that it is not then I go back and look at what I might have done incorrectly and try to re-write the query to get the index behavior I'm looking for. To that end, there's a poll below to ask you if think moving the Show Plan button as the first button would be