Problem context and objectives
Lead systems engineer · Autocomplete Crossroads
Design search autocomplete that returns ranked suggestions while users type, incorporates trends, and filters unsafe terms.
The design must survive queries 500K/s and latency p99 < 50 ms. Every box must earn its place by satisfying a requirement or containing a failure.
How you win
- 1Trace one user action from request to durable outcome
- 2Connect every component to a stated requirement
- 3Explain the losing tradeoff, not only the chosen technology
Rules and pressure
- queries: 500K/s
- latency: p99 < 50 ms
- Prefix suggestions
- Personalization
New words in this mission
Open a term for a plain-language explanation.p99 latency+
If 100 actions are measured, about 99 finish within this time. Teams use it to notice the experience of nearly the slowest users.
latency+
The waiting time from starting an action until its result is available. Lower latency makes interactions feel more immediate.
Live architecture trace
Autocomplete Crossroads: request to outcome
Search box sends “prefix” to Suggestion edge. Precomputed top candidates per normalized prefix make the online path a bounded lookup and rerank.
Design search autocomplete that returns ranked suggestions while users type, incorporates trends, and filters unsafe terms. Follow one real user action through the complete architecture; a component is useful only when you can explain the request, state, or failure it handles.