Data Warehousing For Dummies®, 2nd Edition

Chapter 22. Existing Sort-of Data Warehouses: Upgrade or Replace?

In This Chapter

• Taking a complete inventory of your organization's extract files

• Deciding what to do with each extract file

• Mastering the complexities of migrating extract files to a real data warehouse

• Recognizing that you (almost) never want to take away user functionality

Your organization has overwhelmingly favorable odds of having at least one sort-of data warehouse — a reporting system that provides informational capabilities and, sometimes, analytical capabilities to one or more groups of users. Your users probably use the term extract file to describe this type of environment because it's populated by extracts of data from production systems, rather than by users being forced to execute their queries or receive their reports from the operational production databases or files. Still interested in playing the odds? Here are a few more examples of types of data environments that might be described as sort-of data warehouses:

• Although the extracted data is almost always housed in a single file or database, a merge process probably combines extracted data from more than one application source.

• Only selected elements, not all elements from all tables or files, from each data source are usually extracted and copied to the extract file.

• Some sort of data quality assurance process is usually going on each step of the way, from the initial extract to loading the data into the extract file.

• Some power users probably can execute ...