Inside Microsoft® SQL Server™ 2005, Fourth Edition

Special Indexes

SQL Server 2005 allows you to create two special kinds of indexes: indexes on computed columns and indexes on views. Without indexes, both of these constructs–computed columns and views–are purely logical. There is no physical storage for the data involved. A computed column is not stored with the table data; it is recomputed every time a row is accessed. A view does not save any data; it basically saves a SELECT statement that is re-executed every time the data in the view is accessed. With the new special indexes, SQL Server actually materializes what was only logical data into the physical leaf level of an index.

Prerequisites

Before you can create indexes on either computed columns or views, certain prerequisites must be met. ...