CHPL Lake — the boring parts

A data lake for our specific public library institution — presented to the Cincinnati & Hamilton County Public Library senior leadership team, 19 August 2026.

Sierra is built to run the library right now: it changes records in place and lets the past go. That is correct behavior for an operational system, and it means the library's own history is nobody's job unless we make it somebody's job. So we keep our own copy — captured on a schedule, never edited afterward, refined into answers that can be rebuilt at any time.

▶ The talk v1.1.0

Open the deck →
reveal.js · →/Space next · ← back · F fullscreen · Esc overview. On a phone it becomes a single scrolling page.

📄 The handout v1.0.0

One-page leave-behind — flat, US Letter, print one side.
Download PDF (v1.0.0)

Issue #8 of the concept-zine series. The QR printed on the sheet resolves to this page.

What it has answered

• Delhi Township closes Aug 29 — 751 titles where that branch holds every active copy, 733 of them the only physical item we own. Read the report →
• Northern Kentucky borrowing ends Jan 3 — roughly 10,363 cardholders to reach.
• Temporary cards — 5,276 on file, 2,394 already past expiry.
• Items stuck in transit — 3,829 surfaced a month, with a printable pull sheet per branch.
• Loan rules against published policy — where what we tell the public and what the system does disagree.
• Collection pressure by location — which shelves carry more than their share, and which are bare.
• Reading lists on the public web — live, rebuilt nightly. chimpy-reader →
• Vendor delivery verification — proving a file arrived when no log survived to say so.
• Holdings maintenance with OCLC — moving from manual to scheduled.

Every one of these is the same machinery, pointed at a different question.

More

• Concept zines — June 2026: dbt, chimpy-reader, the medallion, the roadmap, the schemas.
• Our Data, Our Lake — the May 2026 briefing this one follows.
• chimpy-lake showboats — narrated walkthroughs of the working system.

The deck and the handout are versioned independently (semver). This page always serves the current version of both; the QR code on the printed handout, and the QR on the deck's title slide, both resolve here.