Oracle9i OLAP Services Developer's Guide to the Oracle OLAP API Release 1 (9.0.1) Part Number A88756-01 |
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Understanding OLAP API Metadata, 6 of 10
An MdmLevel
is an MdmHierarchicalDimension
whose parents and children are elements from other MdmLevel
objects. The elements from a given MdmLevel
correspond to a subset of the elements in an MdmHierarchy
.
A given MdmLevel
is based on a level that was specified by a database administrator in the OLAP management feature of Oracle Enterprise Manager. Typically, the database administrator specified a column in a database table to provide the elements for the level.
Even though the elements of an MdmLevel
have parent-child relationships, an MdmLevel
is represented as a simple list. The parent-child relationships among the elements are recorded in the parent and ancestors attributes, which you can obtain by calling the getParentRelation
and getAncestorsRelation
methods on the MdmLevel
. Sometimes the parent and ancestors attributes are referred to as parent and ancestors relations.
Typically, an MdmLevel
has an MdmBaseDimensionDefinition
, because the underlying data is structured as a single list.
The list of elements in an MdmLevel
includes only the elements in that one level. The values of the elements must be unique. However, uniqueness can be achieved by a database administrator who defines the level using two relational columns. For example, a level that represents cities can be defined in the relational database based on both the city column and the state column. This makes it possible for the value "Springfield" to appear for two different elements in the city level: one appears for Springfield, Illinois and another appears for Springfield, Massachusetts.
The following table lists the elements for an MdmLevel
called mdmQuarter
, which records the three-month quarters for a level MdmHierarchy
called mdmTimesDimCalHier
. This MdmHierarchy
covers four years, so the number of elements in mdmQuarter
is 16.
Elements of |
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1998-Q1 |
1998-Q2 |
1998-Q3 |
1998-Q4 |
1999-Q1 |
1999-Q2 |
1999-Q3 |
1999-Q4 |
2000-Q1 |
. . . |
2001-Q4 |
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