“When asked about the best way to design and build the ETL system, many designers say, “Well, that depends.” It depends on the source; it depends on limitations of the data; it depends on the scripting languages and ETL tools available; it depends on the staff’s skills; and it depends on the BI tools. But the “it depends” response is dangerous because it becomes an excuse to take an unstructured approach to developing an ETL system, which in the worse-case scenario results in an undifferentiated spaghetti-mess of tables, modules, processes, scripts, triggers, alerts, and job schedules. This “creative” design approach should not be tolerated. With the wisdom of hindsight from thousands of successful data warehouses, a set of ETL best practices have emerged. There is no reason to tolerate an unstructured approach.”