title: How is Amazon DynamoDB throughput calculated and limited?
body: <p>Is it averaged per second?  Per minute?  Per hour?</p>
  
  <p>For example.. if I pay for 10 "read units" which allows for 10 highly consistent reads per second, will I be throttled if I try to do 20 reads in a single second, even if it was the only 20 reads that occurred in the last hour?  The Amazon documentation and FAQ do not answer this critical question anywhere that I could find.</p>
  
  <p>The only related response I could find in the FAQ completely ignores the issue of how usage is calculated and when throttling may happen:</p>
  
  <blockquote>
    <p><strong>Q: What happens if my application performs more reads or writes than
    my provisioned capacity?</strong></p>
    
    <p><strong>A:</strong> If your application performs more
    reads/second or writes/second than your table’s provisioned throughput
    capacity allows, requests above your provisioned capacity will be
    throttled and you will receive 400 error codes. For instance, if you
    had asked for 1,000 write capacity units and try to do 1,500
    writes/second of 1 KB items, DynamoDB will only allow 1,000
    writes/second to go through and you will receive error code 400 on
    your extra requests. You should use CloudWatch to monitor your request
    rate to ensure that you always have enough provisioned throughput to
    achieve the request rate that you need.</p>
  </blockquote>