Constructing a Dimension

Creating a dimension entity is only the first step in constructing the OLAP metadata for a dimension. Each dimension must have at least one level. More typically, it will have multiple levels, hierarchies, and attributes. Table 13-1 shows the parent-child relationships between the metadata components of a dimension.

Table 13-1  Hierarchical Relationships Between Components of a Dimension

Parent Entity	Child Entity
dimension	dimension attribute, hierarchy, level
dimension attribute	level attribute
hierarchy	level
level	level attribute

Procedure: Construct an OLAP Dimension

Generally, you will create hierarchies and dimension attributes after creating the dimension and before creating the dimension levels and level attributes. Once the levels and level attributes are defined, you can map them to columns in one or more warehouse dimension tables. The general steps are as follows:

1. Call procedures in CWM2_OLAP_DIMENSION to create the dimension.
2. Call procedures in CWM2_OLAP_DIMENSION_ATTRIBUTE to create dimension attributes.
3. Call procedures in CWM2_OLAP_HIERARCHY to define hierarchical relationships for the dimension's levels.
4. Call procedures in CWM2_OLAP_LEVEL to create levels and assign them to hierarchies.
5. Call procedures in CWM2_OLAP_LEVEL_ATTRIBUTE to create level attributes and assign them to dimension attributes.
6. Call procedures in CWM2_OLAP_TABLE_MAP to map the dimension's levels and level attributes to columns in a dimension table.