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SYSTEM DESIGNDesign a Search Engine (Inverted Index)GoogleElasticAlgolia
TRAFFIC LEVEL
—/3
CONSTRAINTS
Indexed pages50 billion
Queries/sec100,000
Query latency target< 200ms
Index freshnessNew pages indexed within 5 min
Index size~100 PB
Compute & Network
Load BalancerDistribute traffic
API GatewayEntry point / auth
API ServerBusiness logic
Worker NodeAsync processing
CDN EdgeGlobal cache
WebSocket GatewayPersistent connections
Data Stores
PostgreSQLRelational DB
MySQLRelational DB
CassandraWide-Column DB
DynamoDBNoSQL / Managed
S3 BucketObject storage
Queues & Cache
Redis CacheIn-memory store
KafkaEvent stream
ZookeeperCoordination
Specialized
Bloom FilterProbabilistic set
Rate LimiterThrottling
Geohash ServiceGeospatial index
Trie ServerPrefix search
APNS / FCMPush notifications
AggregatorBatch / roll-up
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🚨 INCIDENT
GoogleElasticAlgolia

Design a full-text search engine that indexes 50 billion web pages and returns results for a query in under 200ms. Handle 100,000 queries/sec. Results must be ranked by relevance (TF-IDF, PageRank). Support near-real-time indexing of new pages within 5 minutes of crawling.

📥 Assigned to:You — Senior Engineer
SCALE LEVELS
1
1,000 RPS
Target: <200ms
2
10,000 RPS
Target: <100ms
3
100,000 RPS
Target: <50ms
GLOBAL SUCCESS RATE
100.0%
P99 LATENCY
45ms
Target: < 200ms
TOTAL RPS INGESTED0 / 11,000
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