The 34 Subsystems of ETL
With an understanding of the existing requirements, realities, and constraints, you’re ready to learn about the 34 critical subsystems that form the architecture for every ETL system. This chapter describes all 34 subsystems with equal emphasis. The next chapter then describes the practical steps of implementing those subsystems needed for each particular situation. Although we have adopted the industry vernacular, ETL, to describe these steps, the process really has four major components:
- Extracting. Gathering raw data from the source systems and usually writing it to disk in the ETL environment before any significant restructuring of the data takes place. Subsystems 1 through 3 support the extracting process.
- Cleaning and conforming. Sending source data through a series of processing steps in the ETL system to improve the quality of the data received from the source, and merging data from two or more sources to create and enforce conformed dimensions...