When you import a cube table into the semantic model's physical layer, Semantic Modeler structures each cube table as a physical cube table, a type of physical table.

A cube contains all of the expected physical table elements, such as columns, keys, and joins. A cube also contains specific multidimensional metadata such as hierarchies and levels. In the physical layer, you can expand a hierarchy to view and work with its levels.

A multidimensional catalog in the data source can contain multiple physical cubes. You can import the metadata for one or more of these cubes into the semantic model.

Oracle recommends that you:

• Import the metadata for cube tables and their components rather than creating cube tables manually.

• Verify that the physical hierarchy's type is set correctly, and verify that the imported physical cube columns' aggregation rule type is set correctly.

• Remove any objects from the physical layer after import such as the cube's hierarchies and columns that you aren't going to use in the logical layer. Eliminating unnecessary objects can result in better performance.

In cases where you create cubes manually, you must build each cube one hierarchy at a time and test each hierarchy before building another. For example, create the time hierarchy and a measure and test it. Then when the cube is correct, you create the geography hierarchy and test it. Creating and testing the cubes you create manually in this sequence ensures that you've set up each cube correctly, and helps you identify any errors as you add each element to the cube.