Call now: (800) 766-1884  


 SQL Server Tips
 SQL Server Training

 SQL Server Consulting
 SQL Server Support
 SQL Server Remote DBA

 SQL Server Scripts
 Scripts Menu




  SQL Server Tips by Gama and Naughter




The concept behind indexes is to change the order of the data (clustered index) or to add metadata (non-clustered index) for improving the performance of queries.


Clustered indexes 

* Physically stored in order (ascending or descending)

* Only one per table

* When a primary key is created a clustered index is automatically created as well.

* If the table is under heavy data modifications or the primary key is used for searches, a clustered index on the primary key is recommended.

* Columns with values that will not change at all or very seldom, are the best choices.

Non-clustered indexes

* Up to 249 nonclustered indexes are possible for each table or indexed view.

* The clustered index keys are used for searching therefore clustered index keys should be chosen with a minimal length.

* Covered queries (all the columns used for joining, sorting or filtering are indexed) should be non-clustered.

* Foreign keys should be non-clustered.

If the table is under heavy data retrieval from fields other than the primary key, one clustered index and/or one or more non-clustered indexes should be created for the column(s) used to retrieve the data.

The above book excerpt is from:

Super SQL Server Systems
Turbocharge Database Performance with C++ External Procedures

ISBN: 0-9761573-2-2
Joseph Gama, P. J. Naughter


Burleson Consulting Remote DB Administration







Burleson is the America's Team

Note: The pages on this site were created as a support and training reference for use by our staff of DBA consultants.  If you find it confusing, please exit this page.

Errata?  SQL Server technology is changing and we strive to update our SQL Server support information.  If you find an error or have a suggestion for improving our content, we would appreciate your feedback.  Just  e-mail:and include the URL for the page.

Burleson Consulting
SQL Server database support


Copyright 1996 -  2013 by Vaaltech Web Services. All rights reserved.

Hit Counter