Lakehouse Drill Deck

The page to read in the car park. Nothing new — only what you most want loaded when you walk in.

Posture

You are a consultant meeting a client, not a candidate being examined. Ask before you answer. Decide, then say what it costs. Be the most honest person in the room.

The four frameworks

• Design — CLAIM. Context (ask 3–5) → Levers (the 2–3 decisions that decide it) → Architecture (draw) → Implications (what you gave up) → Measure.
• Debug. Symptom → Scope → Evidence → Hypothesis → Test → Fix → Prevent. Never propose a fix before naming the evidence.
• Behavioural — STAR-L. Short S and T, most airtime on A ("I decided…"), R has a number, L is honest.
• Objections. Feel → Felt → Found → Fact. Concede what's true first.

Opening moves

• Any design question: "Before I design anything — what's the freshness requirement, who operates this in a year, and what's the regulatory position?"
• Any performance question: "First: what changed? Then: where is the time going?"
• Any comparison: concede what's true about the competitor, name the dimension that decides it for this customer, recommend, offer coexistence.
• Anything you don't know: "I don't know that specifically. Here's how I'd reason about it, and how I'd verify." Then reason well and move on.

Numbers you'll reach for

Say these as heuristics. False precision is worse than "order of magnitude, roughly X".

Signals of real experience

• "Before I tune anything — what changed?"
• "Max versus median task time in the slowest stage."
• "I'd pin the data with time travel and re-run, to separate a data problem from a code problem."
• "Adding nodes to a skewed job makes it more expensive and exactly as slow."
• "The fix is one thing; the monitor that catches it next time is the deliverable."
• "Governance that can be bypassed isn't governance."

Do not

• Design before asking.
• List features instead of naming a decision and its trade-off.
• Bluff — the only disqualifying failure.
• Use old names: DLT, Workflows, online tables.
• Defend a wrong answer. Say "you're right, I had that backwards" and move on.
• Talk for eleven minutes without a breath.

Currency, one line each

• Lakehouse//RT / Reyden — millisecond SQL on governed Delta/Iceberg, no serving-store copy. Beta, read-only.
• Lakebase / LTAP — serverless Postgres on lake storage; operational writes landing straight in open columnar formats, removing the CDC pipeline. LTAP announced.
• Iceberg v3 GA — deletion vectors, row lineage, VARIANT; Delta and Iceberg can share Parquet files.
• Unity AI Gateway — runtime governance of models/agents/tools: hard spend caps, routing, action policies, guardrails, tracing.
• UC Metrics / Domains / Glossary — the governed semantic layer.
• Omnigent — open-source meta-harness above agent frameworks.

In service of an architecture point. Never recite the list.

Three sentences to have ready

On AI. Everyone has the same models. The differentiator is governed context and runtime control — a data architecture problem, not a model problem.

On cost. I don't want to make the platform cheaper, I want to make it attributable. Once spend is tagged to product teams, they optimise without anyone policing them.

On the role. The job is making architecture repeatable across engagements, so the tenth customer gets the benefit of the first nine — while staying close enough to the metal to be credible when something is on fire.

Last things

• Ask your questions. Having none is a scored failure.
• Close with: "Is there anything about my background that gives you pause? I'd rather address it now."
• Breathe. You have done the work.