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Clustered index vs. non-clustered index

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

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This is a great question. A single clustered index can be created on a table and this index physically sorts the data for the entire table based on the values in this column. A table can have up to 255 nonclustered indexes. Nonclustered indexes are based on order of the data, but do not physically sort the data.

A table can have one of the following index configurations:

  • No indexes
  • A clustered index
  • A clustered index and many nonclustered indexes
  • A nonclustered index
  • Many nonclustered indexes

For more information about clustered indexes visit:

For more information about nonclustered indexes visit:

I hope this is helpful to you!

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This was first published in July 2005

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