What is the difference between Clustered index & Non Clustered Index?

Clustered Index

  • Data is stored in physical order.
  • The leaf nodes of Clustered indexes will contain actual data.
  • Only one clustered index should exist in a table.

 Non-Clustered Index

  • It does not sort the data in physical order. But it will have the exact address of particular data.
  • The leaf nodes of Non-clustered indexes will contain the pointer to the data.
  • We can create Max 999 Non clustered indexes in a table.(As per SQL Server 2008)

Latest Comments
  1. Amit Banerjee

    Non clustered indexes are not *faster* than a clustered index. It depends on the situation. A key lookup or RID lookup is a expensive operation. A blanket statement which makes non-clustered indexes seems better than clustered indexes is incorrect!!

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