A data source defines a particular set of business object instances for reporting purposes. A data source is similar to a database view, except it is more flexible in two key areas. First, a database view always returns a flattened out tabular data structure, whereas a data source can return hierarchical data structures. Second, a database view requires that technical staff manually join related tables together, while a data source automatically allows reportable access to all business objects related to those in the data source.