How to optimize database performance in MSSQL through reorganizing and rebuilding indexes

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The SQL Server 2005 Database Engine automatically maintains indexes whenever insert, update, or delete operations are made to the underlying data. Over time these modifications can cause the information in the index to become scattered in the database (fragmented). Fragmentation exists when indexes have pages in which the logical ordering, based on the key value, does not match the physical ordering inside the data file. Heavily fragmented indexes can degrade query performance and cause your application to respond slowly. For more information, see this Microsoft Web site.

In SQL Server 2005 you can remedy index fragmentation by either reorganizing an index or by rebuilding an index.

A. Rebuilding an index

The following example rebuilds a single index.

USE AdventureWorks;
GO
ALTER INDEX PK_Employee_EmployeeID ON HumanResources.Employee
REBUILD;
GO

B. Rebuilding all indexes on a table and specifying options

The following example specifies the keyword ALL. This rebuilds all indexes associated with the table. Three options are specified.

USE AdventureWorks;
GO
ALTER INDEX ALL ON Production.Product
REBUILD WITH (FILLFACTOR = 80, SORT_IN_TEMPDB = ON,
              STATISTICS_NORECOMPUTE = ON);
GO

C. Reorganizing an index with LOB Compaction

The following example reorganizes a single clustered index. Because the index contains a LOB data type in the leaf level, the statement also compacts all pages that contain the large object data. Note that you do not have to specify the WITH (LOB_Compaction) option because the default value is ON.

USE AdventureWorks;
GO
ALTER INDEX PK_ProductPhoto_ProductPhotoID ON Production.ProductPhoto
REORGANIZE ;
GO