Hi All [SQL Server 2008] I have a table(DATALOG_4) with 10 Millions records. It contains 18 columns. The column DATE_TIME is a primary key column. We have created Non-Clustered Index on DATE_Time because we are using this column in WHERE Clause. The issue is, It takes more than 20 seconds for even after I created Non-Clustered index. We are using the following Query: SELECT DATE_TIME,  AS CT,  AS BID, ROW_NUMBER() OVER (PARTITION BY  ORDER BY DATE_TIME DESC) AS Row_No FROM DATALOG_4 (NOLOCK) WHERE DATE_TIME >= '2012-11-01 12:00:00' and DATE_TIME <= '2012-12-31 11:59:59' Please anyone suggest me, How to make the select Query fast?