Index FAQ

The following section contains several frequently asked questions and answers about indexes.

Q1: How can I view the index selectivity (density) of an indexed column?
A1: The index selectivity can be viewed by using the Transact SQL Statement DBCC SHOW_STATISTICS. DBCC SHOW_STATISTICS displays the average key length of an index, the index density, and the distribution steps.
Q2:What are composite indexes?
A2: Composite indexes are indexes created with two or more columns. (The maximum number of columns for an index is 16.) SQL Server 2000 keeps distribution page and histogram statistics on the columns that make up the index. Try not to get carried away by creating composite indexes with a large number of columns. (I try to keep them under ...

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