Understanding SQL JOIN

Edward Loveall explains a useful frame of mind to understand SQL JOIN statements. The key to understanding them is to know that the SQL statement will act on one relation (called a table in the article). What JOIN statements do, is create a new relation from other relations (or tables). A follow-up explains GROUP BY.

A Data Pipeline is a Materialized View

Nicholas Chammas makes the argument that a data pipeline is a form of a materialized view: A data structured derived from a primary source, and persisted. Thinking about primary vs. derived data resonates with me, and is one of the main take-aways from Designing Designing Data-Intensive Applications.

Do You Need an Event Bus? A Quick Overview of Five Common Uses

The thing that surprised me the most about this article by Lyric Hartley, is that in all 5 examples, the event bus (Kafka) is always fed from a database. It is always used as derived data, and never as a primary. While I think that is a lot of the real-life use cases out there, it leaves out the architectures, like event-driven, that use the even bus as a primary source.