The 38 Subsystems of ETL

IntelligentEnterprise : The 38 Subsystems of ETL (printable version)

The extract-transform-load (ETL) system, or more informally, the “back room,” is often estimated to consume 70 percent of the time and effort of building a data warehouse. But there hasn’t been enough careful thinking about just why the ETL system is so complex and resource intensive. Everyone understands the three letters: You get the data out of its original source location (E), you do something to it (T), and then you load it (L) into a final set of tables for the users to query.