What is Index in sql server

 Index is a database object that makes data retrieval faster. Index will improve the performance of data retrieval . Sql server uses following methods to locate the record. One table Scan and second one indexes Scan.

·        In table Scan sql server scans entire data file.

·        In index scan Sql server scans entire data file.

      Two types of Indexes

1.      Non-Cluster Index

2.       Cluster Index

Non-Cluster Index :  If the order of the values in the index and order of the values in the table I not same then the index is called Non-Cluster

Cluster Index :  If order of the records in the table and order of the records in the index then that is called Clustered index.