Dimensions and Hierarchical Levels

In a business model, a dimension represents a hierarchical organization of logical columns (attributes) belonging to a single logical dimension table. Common dimensions might be 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 are not visible to end users.
In each dimension, you organize attributes into hierarchical levels. These logical levels represent the organizational rules, and reporting needs required by your business. They provide the structure (metadata) that the Oracle BI Server uses to drill into and across dimensions to get more detailed views of the data.
Dimension hierarchical levels are used to perform the following actions:
  • Set up aggregate navigation
  • Configure level-based measure calculations (refer to Level-Based Measure Calculations Example)
  • Determine what attributes appear when Oracle BI Presentation Services users drill down in their data requests
  • Process of Creating and Administering Dimensions

    Each business model can have one or more dimensions, each dimension can have one or more logical levels, and each logical level has one or more attributes (columns) associated with it.
    NOTE:  The concept of dimensions for a multidimensional data source is less complex than for dimensions in other data sources. For example, you do not create dimension level keys. A dimension is specific to a particular multidimensional data source (cannot be used by more than one) and cannot be created and manipulated individually. Additionally, each cube in the data source should have at least one dimension and one measure in the logical layer.
    The following sections explain how to create dimensions:
    • Creating Dimensions
    • Creating Dimension Levels and Keys
    • Creating Dimensions Automatically
    • Creating Dimensions

      After creating a dimension, each dimension can be associated with attributes (columns) from one or more logical dimension tables and level-based measures from logical fact tables. After you associate logical columns with a dimension level, the tables in which these columns exist will appear in the Tables tab of the Dimension dialog box.
      To create a dimension
      1. In the Business Model and Mapping Layer, right-click a business model and select New Object > Dimension.
      2. In the Dimension dialog box, in the General tab, type a name for the dimension.
      3. If the dimension is a time dimension, select the Time Dimension check box.
        NOTE:  The Default root level field will be automatically populated after you associate logical columns with a dimension level.
      4. (Optional) Type a description of the dimension.
      5. Click OK

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