Trade-offs

Trade-off discussion separates senior candidates from diagram drawers. Compare alternatives on latency, consistency, cost, complexity, operability, migration risk, and failure modes. State what you gain, what you pay, and when you would revisit the decision.

Use "we chose X over Y because..." framing. Reference requirements: eventual consistency is fine for activity feeds but not for inventory counts. Acknowledge technical debt accepted for speed.

On interviews: offer two viable options for a contentious choice (SQL vs NoSQL, push vs pull feed), pick one with reasoning, and note the trigger to switch.

Common pitfalls: presenting one option as universally correct; ignoring operational burden; no migration path from MVP to scale.

Checklist:

• Compare at least two alternatives per major choice.
• Link trade-offs to stated requirements.
• State cost, complexity, and failure impact.
• Define when to re-evaluate the decision.