Oracle Consulting Oracle Training Oracle Support Development
Oracle Books
SQL Server Books
IT Books
Job Interview Books
Rampant Horse Books
911 Series
Pedagogue Books

Oracle Software
Write for Rampant
Publish with Rampant
Rampant News
Rampant Authors
Rampant Staff
Oracle News
Oracle Forum
Oracle Tips
Articles by our Authors
Press Releases
SQL Server Books

Oracle 11g Books

Oracle tuning

Oracle training

Oracle support

Remote Oracle


Privacy Policy


  SQL Server Tips by Burleson

Clustered Indexes

There is plenty of debate on whether every table should have a clustered index. Many SQL Server gurus suggest that each table should indeed have a clustered index. But, how can one know what series of columns are best suited for a clustered index?

Since clustered indexes sort the underlying table data in the order defined in the index, columns that are the targets of queries that routinely return single or few rows should not be indexed. Instead, a clustered index should be created on one or more columns that are the object of range searches, because the requested data will be found on the same page or pages within close proximity. The end results of smart clustered index designs are reduced I/O and better query response times for queries that return a range of data.

Another benefit of clustered indexes is that they assist in reorganizing a table. Unlike other database engines, SQL Server has no command for reorganizing a heap table. It only works on indexes. So, if there is a badly fragmented table, the DBA is usually stuck with executing a table purge, copying all the data out, truncating the table, and copying all the data back in. This feat is not easy to accomplish in an environment with high amounts of enforced referential integrity.

If the table has a clustered index, the DBA can simply rebuild the clustered index, which reorganizes the data pages because the leaf level of the clustered index is the data.

The above book excerpt is from:

High-Performance SQL Server DBA
Tuning & Optimization Secrets

ISBN: 0-9761573-6-5
Robin Schumacher  

Linux Oracle commands syntax poster

ION Oracle tuning software

Oracle data dictionary reference poster

Oracle Forum

BC Oracle consulting support training

BC remote Oracle DBA   



 Copyright © 1996 -2017 by Burleson. All rights reserved.

Oracle® is the registered trademark of Oracle Corporation. SQL Server® is the registered trademark of Microsoft Corporation. 
Many of the designations used by computer vendors to distinguish their products are claimed as Trademarks

Hit Counter