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Open Search Engine →Open Instagram Feed →

Search Engine vs Instagram Feed

Search Engine (Google-style)

Search Engine (Google-style)

Web crawl, inverted index, scatter-gather query, ranking.

Components (10)

  • Browser
  • Query Frontend
  • Index Shard 1
  • Index Shard 2
  • Index Shard 3
  • Ranker
  • Doc Store
  • Crawler
  • Bloom Filter
  • Index Builder

Headline numbers

  • Query QPS (avg)~90K/sec
  • Per-shard QPS~9M/sec aggregate
  • Inverted index size~10s of PB
Instagram Feed

Instagram Feed

Fan-out on write vs read, ranking, CDN.

Components (10)

  • Mobile Client
  • CDN
  • API Gateway
  • Feed Service
  • Post Service
  • Kafka
  • Fan-out Worker
  • Redis
  • Postgres
  • S3

Headline numbers

  • Posts / sec (avg)~3,000/sec
  • Feed read QPS~58,000/sec
  • Fan-out writes / sec~600,000/sec

Key differences

Only in Search Engine
  • Index Shard 1
In both
  • Client
  • Api Gateway
  • Service
  • Database
  • Cache
Only in Instagram Feed
  • CDN
  • Kafka
  • S3

Flow shape

Search Engine flows
  • Run a query5 steps
  • Crawl + index a new page4 steps
  • ⚠ One index shard is down4 steps
Instagram Feed flows
  • Post a photo (fan-out on write)7 steps
  • Open feed (precomputed timeline)5 steps
  • ⚠ Fan-out Worker is down7 steps
  • ⚠ Timeline cache flushed (Redis restart)4 steps