Chapter 12. Conclusions
Designing and building an ETL system for a data warehouse is an exercise in keeping perspective. This is a typical complex undertaking that demands a comprehensive plan up front. It's easy to start transferring data from a specific source and immediately populate tables that can be queried. Hopefully, end users don't see the results of this prototype because such an effort doesn't scale and can't be managed.
Deepening the Definition of ETL
We go to considerable lengths in Chapter 1 to describe the requirements you must surround. These include business needs; compliance requirements; data-profiling results; requirements for such things as security, data integration, data latency, archiving and lineage tracking; and end-user tool delivery. You also must fold in your available skills and your existing legacy licenses. Yes, this is an overconstrained problem.
If you simultaneously keep all these requirements in mind, you must make the BIG decision: Should you buy a comprehensive ETL tool or roll your own with scripts and programs? We've made a serious effort to not bias this book too heavily in either direction, but the bigger the scope and the longer the duration of your project, the more we think a vendor-supplied ETL tool makes sense. Your job is to prepare data, not be a software development manager.
The real value of this book, in our opinion, is the structure we have put on the classic three steps of extract, transform, and load. This book describes a specific ...