title: Cosmos DB minimum partitions
body: <p>We have a IoT scenario, with Azure Event Hub as our data ingestion service.Our proposed architecture is, we have a event capture (window = 15 mins) on the EH, use Azure Batch services to process the captured data at end of day/periodic intervals throughout the day and then store in a cold storage (blobs/Data lake).
  We also want to have a pipeline of Event Hub -> Function App -> Cosmos DB, for instantaneous queries which may not be available through the event capture approach (as they won't be instantaneous).With respect to storage of cosmos db, we plan to have a ttl = 24/48 hrs. Now the problem is, if we opt for a partition of deviceId and above ttl we will not utilize the partition effectively (max = 10GB), and have multiple partitions which will impact cost.
  So, my question is what other strategies(other db's/partitioning mechanisms) can we use to optimize(main concern - cost efficiency) database storage ? </p>
  
  <ol>
  <li>Tried Single Partition collection - Wont be useful when to move to a higher scale of devices</li>
  <li>Partitioning by time (hour/minutes), it would mean a pay-upfront model, which is not desired</li>
  </ol>