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What is the difference between clustered and a non-clustered index?

posted Aug 8, 2012, 3:35 AM by Ashish Jain
A clustered index is a special type of index that reorders the way records in the table are physically stored. Therefore table can have only one clustered index. The leaf nodes of a clustered index contain the data pages. In this, the physical sorting of a database table’s rows in the storage media. For this reason, each database table may have only one clustered index.

nonclustered index is a special type of index in which the logical order of the index does not match the physical stored order of the rows on disk. The leaf node of a nonclustered index does not consist of the data pages. Instead, the leaf nodes contain index rows. They are created outside of the database table and contain a sorted list of references to the table itself.