title: Is there a DynamoDB max partition size of 10GB for a single partition key value?
body: <p>I've read lots of DynamoDB docs on designing partition keys and sort keys, but I think I must be missing something fundamental.</p>
  
  <p>If you have a bad partition key design, what happens when the data for a SINGLE partition key value exceeds 10GB?</p>
  
  <p>The 'Understand Partition Behaviour' section states:</p>
  
  <p>"A single partition can hold approximately 10 GB of data"</p>
  
  <p>How can it partition a single partition key?</p>
  
  <p><a href="http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/GuidelinesForTables.html#GuidelinesForTables.Partitions" rel="noreferrer">http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/GuidelinesForTables.html#GuidelinesForTables.Partitions</a></p>
  
  <p>The docs also talk about limits with a local secondary index being limited to 10GB of data after which you start getting errors.</p>
  
  <p>"The maximum size of any item collection is 10 GB. This limit does not apply to tables without local secondary indexes; only tables that have one or more local secondary indexes are affected."</p>
  
  <p><a href="http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/LSI.html#LSI.ItemCollections" rel="noreferrer">http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/LSI.html#LSI.ItemCollections</a></p>
  
  <p>That I can understand. So does it have some other magic for partitioning the data for a single partition key if it exceeds 10GB.  Or does it just keep growing that partition? And what are the implications of that for your key design?</p>
  
  <p>The background to the question is that I've seen lots of examples of using something like a TenantId as a partition key in a multi-tentant environment. But that seems limiting if a specific TenantId could have more than 10 GB of data.</p>
  
  <p>I must be missing something?</p>