tailieunhanh - Mastering Data Warehouse DesignRelational and Dimensional Techniques phần 9

Mỗi hộp ĐỘNG Để chủ đề. (Kỹ thuật này không thể được sử dụng nếu công cụ này không Cung cấp khả năng phân chia mô hình đề vào xem.) Tạo điều kiện cho nhóm Kỹ thuật này của các dữ liệu theo chủ đề và các thực thể cung cấp các quan điểm cho phù hợp. Những thuận lợi chính của kỹ thuật này là: | Maintaining the Models 349 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