How one library question becomes a repeatable answer. The third issue in the concept-zine series (after dbt) explains the medallion — the bronze → silver → gold path a data lake uses to turn raw vendor data into finished, ready-to-use answers.
The worked example: “How did each county use Libby and Hoopla this year vs. last?” — a real cross-source question that, without a lake, means rebuilding the same spreadsheet from scratch every year. With one, it’s an answer you re-order, fresh, any time — and the privacy stays built in (county, not customer).
Cincinnati & Hamilton County Public Library · concept zine series #3 · dbt › medallion › retention · medallion v1.0.0 · 2026-06