Chapter 6 Working with PDMs

Retrieving Multidimensional Objects

You will need to identify fact and dimension tables and views during the design of a data warehouse. Tables and views support multidimensional types, in this section both are referred to as fact and dimension tables.

A fact table stores variable numerical values related to aspects of a business. For example, sales, revenue, budget. These are usually the values you want to obtain when you carry out a decision support investigation.

A dimension table stores data related to the axis of investigation of a fact. For example, geography, time, product. A dimension table should be connected to a central fact table.

You can use the retrieve multidimensional objects feature to highlight the fact and dimension tables in a physical diagram. The Retrieve Multidimensional Object feature analyzes the references between the tables in order to deduce the table type:

Child tables or views become Fact tables or views
Parent tables or views along the path to the child table or view become Dimension tables or views

The new table type is indicated in the Type dropdown list box in the table property sheet. A type icon is also displayed in the upper left corner of the table symbol:

Fact table	Dimension table

To retrieve multidimensional objects:

Select Tools→Multidimension→Retrieve Multidimensional Objects.

A selection box appears.

Select retrieve options in the General tab.

Select the tables that will be transformed in the Selection tab.

If you are using Sybase AS IQ (version 12.0)
If your current DBMS is Sybase AS IQ (version 12.0), an additional check box appears. The option allows you to automatically rebuild join indexes after retrieving multidimensional objects. For more information on rebuilding join indexes, see section Rebuilding Join Indexes in section Support for Sybase Adaptive Server IQ in chapter DBMS Specific Features.

Click OK.

The selected tables are assigned a multidimensional type.