Hi!
Could you define an extra (covering) index on these fields : (ColD,ColB,ColC) and re-run the query?
And could you please script the table, I'm just curious to see all the fields, indexes , ... of this table?
An execution plan would be really helpful, it would help us (and you too) a lot ...
Maybe I didn't read this thread too carefully, but I don't think you answered the question asking how many rows this query returns?
Virgil Rucsandescu