The Business Model and Mapping layer of the Oracle BI repository defines the business, or logical, model of the data and specifies the mapping between the business model and the Physical layer schemas.
Business models are always dimensional, unlike objects in the Physical layer, which reflect the organization of the data sources. The Business Model and Mapping layer can contain one or more business models. Each business model contains logical tables, columns, and joins.
Even though similar terminology is used for logical table and physical table objects, such as the concept of keys, logical tables and joins in the Business Model and Mapping layer have their own set of rules that differ from those of relational models. For example, logical fact tables are not required to have keys, and logical joins can represent many possible physical joins.
Logical tables, joins, mappings, and other objects in the Business Model and Mapping layer are typically created automatically when you drag and drop objects from the Physical layer to a particular business model. After these objects have been created, you can perform tasks like creating additional logical joins, performing calculations and transformations on columns, and adding and removing keys from dimension and fact tables.