How do table indexes come into play when using a view?

Question

I have a view that collects data from several tables. While there are no indexes on the view itself anything that uses the view seems to benefit from the underlying tables having indexes. Are these being used automatically? If they are then what is the point of creating indexes on your views? Any recommended articles on this subject would be welcomed.

Answer 1

Yes, the underlying table indexes are used automatically - a view just pulls the data from the underlying tables after all.

With regards to the benefits of creating indexes on a view, see this MS Technet article. Small excerpt:

Using indexes to improve query performance is not a new concept; however, indexed views provide additional performance benefits that cannot be achieved using standard indexes. Indexed views can increase query performance in the following ways:

• Aggregations can be precomputed and stored in the index to minimize expensive computations during query execution.
• Tables can be prejoined and the resulting data set stored.
• Combinations of joins or aggregations can be stored.

Answer 2

The query optimizer rewrites the query and "flattens" the use of sub-queries (which a view really is). So underlying indexes will be used.