Solving Operational Business Intelligence with InfoSphere Warehouse Advanced Edition

104 Solving Operational Business Intelligence with InfoSphere Warehouse Advanced Edition

A new overview diagram is created and opened within the main working area,

as shown in Figure 4-13.

Figure 4-13 Reduced logical data model showing our star schema

It is at this point in the development process that you look to de-normalize your

fact and dimensional entities within your logical data model, with the aim of

creating a set of entities that represent a star schema model.

4.3.3 Add dimensional notation to the logical data model

The next stage in the process of developing our OLAP database is to add

dimensional notation to our logical data model, thus moving it closer to the goal

of a logical dimensional model.

We perform these steps to add dimensional notation to the logical data model

with IBM InfoSphere Data Architect:

1. Open our Redbooks Model project and select the new logical data model

IND_CST_DYN_FACT.ldm.

Chapter 4. Data modeling: End to end 105

2. Right-click the model to display the option menu. Select Use Dimensional

Notation.

As shown in Figure 4-14 on page 106, the icon depicting our logical data

model in the Data Project Explorer area has now changed from a type of book

icon to a three arrow book icon representing three dimensions.

However, as shown within this figure, the icons representing the entities listed

beneath these changed book icons still remain as blue squares.

3. Right-click the model again to display the option menu. Select the new menu

option Discover Facts and Dimensions. The tool automatically discovers

and annotates which entities within the model are either dimensional or fact.

4. During the discover process, a wizard window appears and asks if to

generate the hierarchy for each discovered dimension. For our example, we

select Yes.

At the end of this discover process, the blue square entity icons of the

dimensional logical model changed to represent their associated function of

either being a fact, dimensional, or outrigger entity type. Entities that the tool

cannot determine an appropriate entity type remain a blue square. These

particular entities can be set manually to an appropriate entity type using the

Set Dimensional Notation To option on the right-click menu.

Note also that an additional menu option Generate Hierarchy appears that

can be used to create a dimension hierarchy. Using the same menu, you also

can add additional levels to the hierarchy.