Microsoft® SQL Server 2012 Unleashed

Indexed Views

You establish indexed views by creating a unique clustered index on the view itself, independent of the member tables that it references. The creation of this unique index transforms a view from an object that is virtual in nature to one that has physical storage associated with it. Like all other indexes, the index on a view takes up physical storage, requires maintenance, and, most importantly, can provide performance benefits that justify its creation.