Getting the Root MdmSchema

Function of the root MdmSchema

The metadata objects that are accessible through a given MdmMetadataProvider are organized in a tree-like structure, with the root MdmSchema at the top. Under the root MdmSchema are MdmMeasure objects, MdmDimension objects, and one or more MdmSchema objects, which are referred to as subschemas.

Subschemas have their own MdmMeasure and MdmDimension objects. Optionally, they can have their own subschemas as well.

The root MdmSchema contains all the MdmMeasure and MdmDimension objects that are in the subschemas. Therefore, a given MdmMeasure or MdmDimension always appears twice in the tree. It appears once under the root MdmSchema and again under the subschema.

The starting point for discovering the available metadata objects is the root MdmSchema, which is the top of the tree. The following diagram illustrates an example in which one subschema has two MdmMeasure objects and two MdmDimension objects. Another subschema has one MdmMeasure object and two MdmDimension objects. The root MdmSchema contains, in addition to the two subschemas, all three MdmMeasure objects and all four MdmDimension objects.

Using the OLAP management feature of Oracle Enterprise Manager, a database administrator arranges dimensions and measures under one or more top-level measure folders. When OLAP Services maps the measure folders to MdmSchema objects, it always creates the root MdmSchema above the MdmSchema objects for the top-level measure folders. Therefore, even if the database administrator creates only one measure folder, its corresponding MdmSchema will be a subschema under the root.

For more information about MDM metadata objects and how they map to OLAP objects in the OLAP management feature of Oracle Enterprise Manager, see Chapter 2.

Calling the getRootSchema method

The following code gets the root MdmSchema for an MdmMetadataProvider called mp.

MdmSchema root = mp.getRootSchema();