Technical proficiency
Probe depth in lakehouse storage formats: Delta Lake, Iceberg or Hudi, partitioning and file compaction strategy, Spark tuning, and catalogue tooling such as Glue or Unity Catalog.
Evidence to listen for
- Command of the languages, frameworks, and data tools the role actually uses
- Understands correctness, performance, and failure modes, not just syntax
- Has opinions on testing and can justify them
- Reads and reasons about code they did not write
Five-point scoring guide
Cannot work independently; fundamentals are missing.
Weak fundamentals; output needs heavy review.
Competent for the role; needs guidance on complex or unfamiliar work.
Strong practitioner; handles hard problems with little guidance.
Names table formats used in production, explains compaction and Z-ordering choices, and quotes concrete query latency or storage cost effects.