Communicating trade-offs
Say what each choice gains, what it costs, by how much, and when you would choose differently. Tie decisions to requirements and handle pushback without folding.
20 min5 steps
By the end you can
- State a trade-off as the option, what it gains, what it costs, and when you would choose otherwise
- Put a number on a trade-off's cost, such as the latency added by synchronous replication
- Tie each design decision back to a stated requirement, and respond to pushback with reasons
The shape of a good trade-off
Option
- Async replication to region 2
Gains
- Writes stay about 5 ms, not 70
Costs
- Regional failure loses last seconds
Condition
- Fine for likes
- Payments: synchronous
Put a number on it
- Asynchronous5 ms
- Synchronous, cross-region70 ms
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Trace every decision to a requirement
When the interviewer pushes back
1
Restate the concern
2
Re-check against requirements and numbers
3
Defend with reasons, or change and say why
Check your mastery
Rubric
trade-off communication
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