What is an indexed view?

An indexed view is a view whose result is physically materialized through an index. The first index created on it must be a unique clustered index. Additional indexes can then be added. Indexed views have strict requirements, including schema binding and restrictions on allowed query constructs. They can improve specific aggregation or read-heavy workloads, but they add storage and write-maintenance cost because underlying data changes must also maintain the indexed view. They should be introduced only after measuring the workload and understanding SQL Server edition and optimizer behavior relevant to the environment.