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Open Dynamo-Style KV Store →Open Instagram Feed →

Dynamo-Style KV Store vs Instagram Feed

Dynamo-Style KV Store

Dynamo-Style KV Store

Leaderless replication, vector clocks, sloppy quorums, hinted handoff: the architecture behind DynamoDB and Cassandra.

Components (6)

  • Client
  • Coordinator Node
  • Storage Node A
  • Storage Node B
  • Storage Node C
  • Anti-Entropy (Merkle)

Headline numbers

  • Raw storage~300 TB
  • Per-node QPS~10K–20K req/sec
  • Replication write amplification3x
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 Dynamo-Style KV Store
None.
In both
  • Client
  • Service
  • Database
Only in Instagram Feed
  • CDN
  • API Gateway
  • Kafka
  • Redis
  • S3

Flow shape

Dynamo-Style KV Store flows
  • Write with quorum (W=2, N=3)3 steps
  • ⚠ Sloppy quorum + hinted handoff4 steps
  • Concurrent writes create siblings4 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