How DynamoDB Burst and Adaptive Capacity Handle Uneven Traffic Automatically

Amazon DynamoDB uses two automatic mechanisms — burst capacity and adaptive capacity — to prevent hot partitions from throttling under uneven workloads. Burst capacity reserves up to 300 seconds of unused partition throughput to absorb short traffic spikes, though it cannot be manually configured or relied upon for planning. Adaptive capacity redistributes idle throughput from underused partitions toward a hot one, and since May 2019 this rebalancing takes effect almost instantly at no extra cost. In extreme cases, DynamoDB can isolate a frequently accessed item onto its own partition, allowing a single key to use the full partition ceiling of 3,000 read units and 1,000 write units per second. Neither mechanism overrides the hard per-partition limit, meaning a truly hot key will still throttle once that physical ceiling is reached, making good key design essential.