Can performance increase by adding a unique key for table scans?
Yes, the performance increases if you add a unique key for table scan search criteria. Let’s see an actual demonstration of the same. So right click on the table field and create a unique key on customer code field as shown in the below figure. Now let’s go to SQL Server analyzer and set the statistics to ‘ON’ using ‘set statistics io on’. With the statistics we also execute our query with the customer code criteria as shown in the below code snippet.
