Composite Keys and Complex Joins
Fact tables often have several columns that uniquely identify one row of data. In the sample Island Resorts Marketing universe, the CUST_ID and INV_ID columns uniquely identify the records in the SALES table. These two columns together are called a composite key.
Lookup or dimension tables also may have a composite key. Neither of the SAP BusinessObjects sample universes contain lookup tables with composite keys, and well-designed data warehouses also should not require them. However, early data warehouses often used composite keys, and transaction systems still do.
For example, to track changes in customer reference data, the month and year may be part of the composite key. To illustrate this concept, we have ...
Get SAP BusinessObjects BI 4.0 The Complete Reference 3/E now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.
