title: Scaling Cosmos DB
body: <p>I have a few questions about scaling Cosmos DB, I wasnt able to verify using the offical documentation.
  A partition key like a userid puts every unique userid into one logical partition and this partition is stored in one physical partition. For a collection with like 2500-5000 RU/s cosmos db provides ten physical partitions, each with a throughput of 250-500 RU/s. Please correct me if i was wrong till now. Another point: Im interested in Cosmos DB with DocumentDB-API.</p>
  
  <p>Now the question: How exactly is the automatically scaling of Cosmos db working? I guess they scale the physical partitions in any way but how exactly is this working. If one physical partition reach his throughput, is there any scaling? Will the logical partitions which are consuming much throughput be moved into another physical partition with free throughput? And what happens if one physical partition reaches its storage limit? Will Cosmos db provide more physical partitions? If yes, the maximum throuhput would be splitted into the number of the current physical partitions, is this correct as far?</p>