ORIGINAL COMPANY-CONTEXT PRACTICE
Evolve equipment event fields without changing their meaning silently
Original practice scenario: A hypothetical semiconductor-equipment analytics interface changes a pressure field from one unit to another and adds a chamber identifier. Design a compatible event contract.
Written for independent practice using company context; this is not a verified question from a company interview.
A REASONED APPROACH
Model answer.
Version semantic changes explicitly and validate event context before calculation. Keeping the same numeric field name after a unit change can corrupt analysis without triggering a parser failure.
Work through it
- Define required equipment, chamber, event-time and measurement fields with explicit units and schema version, distinguishing unknown chamber mapping from a valid shared-tool event.
- Implement a reviewed adapter for supported old versions, retaining original values and conversion provenance rather than silently accepting every shape.
- Reject ambiguous versions, preserve idempotent event identities and test unit boundaries, missing chamber references and replayed events under the new consumer.
Tradeoffs to discuss
- Adapters reduce producer coordination but increase supported-state complexity; a clean cutover simplifies consumers while requiring stronger rollout control.
Common pitfalls
- Do not infer units from a typical numeric range.
- A newly required chamber dimension may reveal that historical tool-level records cannot be honestly assigned to one chamber.