If EMR and Glue are "heavy engines for distributed large-scale processing," AWS Lambda is the opposite philosophy. No servers running, tiny code snippets execute the instant an event fires, then vanish. In data engineering, Lambda isn't "massive transformation"—it's "lightweight, instant, event-reactive transformation."
Today's core question is simple: when is Lambda appropriate, and when isn't it? Wrong Lambda choices hit time and memory walls, causing mid-task failure. Understanding that boundary precisely is critical for exams and real work.
Lambda is defined by three traits.