|Oracle9i OLAP Services Developer's Guide to the Oracle OLAP API
Release 1 (9.0.1)
Part Number A88756-01
Discovering the Available Metadata, 2 of 8
The OLAP API provides access to a collection of Oracle data for which a database administrator has created metadata using the OLAP management feature of Oracle Enterprise Manager. This collection of data and metadata is the data store for the application. Both the data and the metadata reside in the Oracle database instance.
Potentially, the data store includes all of the measure folders that were created by the database administrator in the OLAP management feature of Oracle Enterprise Manager. However, the scope of the data store that is visible when a given application is running depends on the database privileges that apply to the user ID through which the connection was made. A user sees all of the measure folders (as
MdmSchema objects) that the database administrator created, but the user sees the measures and dimensions that are contained in those measure folders only if he or she has access rights to the relational tables on which the measures and dimensions are based.
When the database administrator created the metadata, Oracle Enterprise Manager made measures, dimensions, and other OLAP objects. In the OLAP API, these objects are accessed as multidimensional metadata (MDM) objects, as described in Chapter 2. The mapping between the OLAP objects from Oracle Enterprise Manager and the MDM objects is automatically performed by OLAP Services.
The metadata objects in the data store help your application to make sense of the data. They provide a way for you to find out what data is available, how it is structured, and what its characteristics are.
Therefore, after connecting, your first step is to find out what metadata is available. Armed with this knowledge, you can present choices to the end user about what data should be selected or calculated and how it should be displayed.
Before investigating the metadata, your application must make a connection to the OLAP service and its parent Oracle database, as described in Chapter 3. Then, your application performs the following steps:
MdmSchema, which include
MdmSchemaobjects. In addition, get the contents of any subschemas.
MdmDimension. For example, for each
MdmDimensionobjects, and for each
MdmDimensionfind out whether it is a union
MdmHierarchy, a level
MdmLevel, or an
The next four topics in this chapter describe these steps in detail.
After you discover the metadata, you typically go on to create queries for selecting, calculating, and otherwise manipulating the data. In order to work with data in these ways, you must get the
Source objects that OLAP Services has created to represent the data for querying. These
Source objects are referred to as primary
This chapter focuses on the initial step of discovering the available metadata, but it also briefly mentions the step of getting a primary
Source from a metadata object. Subsequent chapters of this guide explain how you work with primary
Source objects and create queries based on them.