|Oracle9i OLAP Developer's Guide to the OLAP API
Release 2 (9.2)
Part Number A95297-01
Discovering the Available Metadata, 4 of 8
Getting the root
MdmSchema is the first step in exploring the metadata in your data store.
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
MdmDimension objects and one or more
MdmSchema objects, which are referred to as subschemas. In addition, if there are any
MdmMeasure objects that do not belong to a subschema, they are included under the root.
Subschemas have their own
MdmDimension objects. Optionally, they can have their own subschemas as well.
MdmSchema contains all the
MdmDimension objects that are in the subschemas. Therefore, a given
MdmDimension typically appears twice in the tree. It appears once under the root
MdmSchema and again under the subschema. If an
MdmDimension does not belong to a subschema, it is listed only under the root.
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
MdmSchema that has two subschemas and four
Using the OLAP Metadata APIs, a database administrator arranges dimensions and measures under one or more top-level measure folders. When Oracle OLAP 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 metadata objects, see Chapter 2, "Understanding OLAP API Metadata".
The following code gets the root
MdmSchema for an
MdmMetadataProvider called mp.