MediumSearch35 min

Design Search Autocomplete

Design a search autocomplete/typeahead system that suggests queries as users type, like Google Search suggestions.

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Functional Requirements

Return top 5-10 suggestions as user types each character
Suggestions ranked by popularity/relevance
Low latency: <100ms per keystroke
Update suggestions based on trending queries
Handle multiple languages

Steps (0/6)

Step 1: Clarify Requirements

Scale: 10B search queries/day. Each query averages 4-5 keystrokes triggering autocomplete. ~50B autocomplete requests/day → ~580K QPS. Top 5 suggestions per prefix. How often are suggestions updated? Real-time trending?

Key Points

~580K autocomplete QPS
Response time <100ms (ideally <50ms)
Top 5 suggestions ranked by frequency/popularity
Suggestions updated hourly or daily, with real-time trending overlay

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