Chapter 9. Metadata
Metadata is an interesting topic because every tool space in the data warehouse arena including business intelligence (BI) tools, ETL tools, databases, and dedicated repositories claims to have a metadata solution, and many books are available to advise you on the best metadata strategies. Yet, after years of implementing and reviewing data warehouses, we've yet to encounter a true end-to-end metadata solution. Instead, most data warehouses have manually maintained pieces of metadata that separately exist across their components. Instead of adding to the metadata hoopla, this chapter simply covers the portions of metadata that the ETL team needs to be aware of—either as a consumer or a producer. We propose a set of metadata structures that you need to support the ETL team.
PROCESS CHECK Planning & Design:
Requirements/Realities → Architecture → Implementation → Release to Ops
Data Flow: Extract → Clean → Conform → Deliver
Because the ETL system is the center of your data warehouse universe, it often assumes the responsibility of managing and storing much of the metadata for the data warehouse. One might think that there is no better place than the ETL system for storing and managing metadata because the environment must already know the specifics of all data to function properly. And the ETL process is the creator of the most important metadata in the data warehouse—the data lineage. The data lineage traces data from its exact location in the source system and ...