Microsoft® SQL Server 2012 Unleashed

Indexes on Views

SQL Server 2012 supports the creation of indexes on views. Like indexes on tables, indexes on views can dramatically improve the performance of the queries that reference the views. By nature, a view is a virtual table and does not have a separate data structure as does a table, even though it can be referenced like a table. After an index is created on a view, the result set of the view is stored in the database, just as it would be for a table. The indexed view is no longer virtual because it requires maintenance as rows are added to, deleted from, or modified in the tables referenced by the view. Refer to Chapter 23 for a more detailed discussion of views.

The first index created on a view must be a unique clustered index. ...