quote:Are the following secondary non-clustered indexes the same due to hidden column?
The clustered index is keyed on EventID. #2 is keyed on UserID; EventID will be included in the index because it's part of the clus key, but it will not be part of the key. This index could be very useful.
Indexes #1 and #3 aren't needed, since EventID is unique and is already the clustering key.