Background Typically sales, marketing and financial data warehouses are regarded by their users as 3-dimensional data cubes. Each cell of the cube contains related data such as sales units, sales dollars, price etc. The geography and product dimensions contain hierarchies that model the corporate structure. A transaction in a data warehouse is a customer purchasing an SKU at some point in time.
Aggregates contain summary data for all the possible combinations at all levels in both hierarchies.
Relational Databases Data cubes are a useful representation of warehouse data, particularly for aggregation and pivoting dimensions. They do not store data very efficiently however since the cubes have cells in them for all possible intersections of the dimensions. Relational databases do not store non-existing intersections and for this reason are more common for data warehouses. The standard access method for relational databases is the SQL language. SQL is notably inefficient is its aggregating capabilities.