Shards, Partition Keys, and Throughput

~10 min read

How Kinesis divides a stream into parallel lanes and distributes records across them.

Shards, Partition Keys, and Throughput is a Pro topic

Sign in, then upgrade to Pro or Power to unlock this topic and the full AWS curriculum.

Key points

  • Total throughput = sum of shard capacities; Provisioned mode requires manual shard planning, On-Demand scales automatically
  • Each shard: ~1MB/sec write, ~2MB/sec read (shared unless Enhanced Fan-Out)
  • Partition key determines shard assignment; same key = same shard = preserved relative order
  • Poor partition key choice creates hot shards, mirroring DynamoDB's hot partition problem