Data Warehouse Design Solutions

FOREWORD

The timing of this book in mid-1998 coincides with some fundamental shifts in the data warehousing market. Data warehousing has recently entered a more mature phase where most larger organizations have already built their first data warehouse or they at least are completing their first data warehouse. Many thousands of IS professionals have more than a passing acquaintance with data warehousing and all these professionals know that the data warehouse is very different from the transaction processing system. We have come a long way...

At the same time, many of the original assumptions about data warehousing have fallen by the wayside. At the beginning of this decade we thought the data warehouse was a highly-summarized tool for senior management, something just slightly more flexible than the annual report. We thought we couldn't change anything once it entered the data warehouse, and frankly, we thought of the data warehouse as an expensive luxury for occasional analysis. At the beginning of the 1990s, we designed data warehouses like a big aircraft manufacturer designs an airplane. Or at least it felt that way. The data warehouse design task was a significant undertaking. We thought we had to understand and anticipate all the uses of the data warehouse and we couldn't release any data from it until the data warehouse was complete.

We added to the complexity of the design task by using entity-relation modeling all the way from data cleaning through to data presentation. ...