tailieunhanh - Data Modeling Techniques for Data Warehousing phần 10

Trong ý nghĩa đó, một mô hình dữ liệu lịch sử có thể được phát triển bằng cách sử dụng một cách tiếp cận mô hình chiều. Trong bối cảnh của mô hình công ty kho dữ liệu, xây dựng xương sống của một kho dữ liệu quy mô lớn, chúng tôi tin rằng điều này làm cho không có ý nghĩa. | duplicate is detected a sequence number is appended to the name. This check is repeated until the name and sequence number combination are determined to be unique. Once uniqueness has been confirmed the update insert takes place. Selection Logic Only new or changed rows are selected. Name Customer Location Table Conversion Rules Rows in each customer location table are copied on a daily basis. For existing customer locations the ship-to address is updated. For new customer locations the key is generated and a row inserted. Selection Logic Only new or changed rows are selected. Attributes Name Customer Key Definition This is an arbitrary value assigned to guarantee uniqueness for each customer and location. Alias None Change Rules Once assigned the values of this attribute never change. Data Type Numeric Domain 1 - 999 999 999 Derivation Rules A system generated key of the highest used customer key 1 is assigned when creating a new customer and location entry. Source System Generated Name Name Definition This is the name by which a customer is known to CelDial. Alias None Change Rules When a customer name changes it is updated in place in this dimension. Data Type Character 30 Domain Derivation Rules To ensure the separation of data for customers who have the same name but are not part of the same organization a number will be appended to names where duplicates exist. Source Name in Customer Table Name Ship-to Address Definition This is an address where CelDial ships goods to a corporate customer. It is possible for a corporate customer to have multiple ship-to locations. For retail customers no ship-to address is kept. Therefore there can only be one entry in the customer dimension for a retail customer. Alias None Change Rules When a ship-to address changes it is updated in place in this dimension. Data Type Character 60 Appendix A. The CelDial Case Study 175 Domain All valid addresses within CelDial s service area. Derivation Rules The ship-to address is a .