Maintaining the Models

correspond to each subject area. (This technique cannot be used if the tool does not provide the ability to divide the model into subject area views.) This technique facilitates the grouping of the data entities by subject area and the provision of views accordingly. The major advantages of this technique are: ■■ Each entity is assigned to a subject area and the subject area assignment is clear. ■■ If a particular data steward or data modeler has responsibility for a specific subject area, then all of the data for which that person is responsible is in one place. ■■ Information can easily be retrieved for specific subject areas. The major disadvantage of this technique is that the subject area view is fine for developing the data model, but a single subject area rarely provides a complete picture of the business scenario. Hence, for discussion with business users, we need to create additional (for example, process-oriented) views, thereby increasing the maintenance work. Including the Subject Area within the Entity Name The third approach is to include the subject area name or code within the entity name. For example, if the Customers subject area is coded CU and the Products subject area is coded PR, we would have entities such as CU Customer, CU Prospect, PR Item, and PR Product Family. The major advantages of this approach are: ■■ It is easy to create the initial entity name with the relationship to the subject area. ■■ It is independent of the data-modeling tool. ■■ There is no issue with respect to displaying the relationship between an entity and a subject area. ■■ Alphabetic lists of entities will be grouped by subject area. The major disadvantages of this approach are: ■■ The entity name is awkward. With this approach, the modeler is moving away from using business-meaningful names for the entity names. ■■ Maintenance is more difficult. It is possible to have an entity move from one subject area to another when the subject area is refined. A refinement, for example, may change the definition of subject areas, so that with the revised definition, some of the entities previously assigned to it may need to be reassigned. With this approach, the names of the entities must change. This is a relatively minor inconve