1. Managing Metadata Repositories for Oracle Analytics Server
  2. Build Your Metadata Repository
  3. Work with Logical Dimensions
  4. About Working with Logical Dimensions

About Working with Logical Dimensions

In the Business Model and Mapping layer, a dimension object represents a hierarchical organization of logical columns (attributes).

You can associate one or more logical dimension tables with one dimension object.

Common dimensions include time periods, products, markets, customers, suppliers, promotion conditions, raw materials, manufacturing plants, transportation methods, media types, and time of day. Dimensions exist in the Business Model and Mapping (logical) layer and in the Presentation layer.

In each dimension, you organize logical columns into the structure of the hierarchy. The structure represents the organization rules and reporting needs required by your business and provides the metadata the Oracle BI Server uses to drill into and across dimensions to get detailed views of the data.

There are two types of logical dimensions:

  • Dimensions with level-based hierarchies (structure hierarchies)

    In level-based hierarchies, members are of several types, and members of the same type occur only at a single level.

  • Dimensions with parent-child hierarchies (value hierarchies)

    In parent-child hierarchies, members all have the same type.

Oracle Analytics Server also supports a special type of level-based dimension, called a time dimension, that provides special functionality for modeling time series data.

Because dimensions for multidimensional data sources are defined in the source, you don't create dimension level keys. A dimension is specific to a particular multidimensional data source. You can't create and manipulate a dimension individually. Each cube in the data source should have at least one dimension and one measure in the Business Model and Mapping layer.

You can expose logical dimensions to Answers users by creating presentation hierarchy objects that are based on particular logical dimensions. Creating hierarchies in the Presentation layer enables users to create hierarchy-based queries, see Work with Presentation Hierarchies and Levels.

You can also expose dimension hierarchies by adding one or more columns from each hierarchy level to a subject area in the Presentation layer. Answers supports drill-down on these hierarchical columns.