Questionable duplicate index suggested by optimization
The index suggested by the system is a much better fit for the query you have shown. You should aim to have columns with equality predicates as the leading columns.
Consider a phone book ordered by lastname, firstname
. If your rquirement is to find all people with surnames between "Brown" and "Yates" and a first name of "John" then you need to read most of the phone book. If the phonebook was instead ordered by firstname, lastname
you could easily find the "John" section and the first "Brown" in the section then all you need to do is read all the names until the lastname
is after "Yates" or a new firstname is encountered.
It might not be the ideal index. Potentially you should just change the key columns in the clustered index to this order rather than creating a new one though. You need to evaluate this based on knowledge of your workload.