title: nonclustered index on primary key column?
body: <p>I have a primary key on a table (say ContactID). SQL Server automatically creates and maintains a clustered INDEX on this column. When I ran the Tuning Advisor (against a performance trace), it seemed to recommend another INDEX on the same column - a NON CLUSTERED index on the contactID column. How will this help - since there is already a clustered index on the column? </p>