We have set up IoT architecture where we have multiple device sending MQTT messages to Iot Hub. Then the telemetry messages from IoT Hub is routed to a event hub(custom) endpoint. The event hub has four partitions .
We are consuming the messages using default consumer group. The question I have is how the device telemetry will be stored across the partitions ?.If it is based on a hash function on DeviceId , the partition key will be unique for 1000's of devices , so in that case whether a single partition is sufficient or your suggestion would be using multiple partitions(i.e Is there any chance of performance improvement if we use multiple partitions).One more question is we are reading event from Event Hub using Event Processor client , the retrieved events have the PartitionKey Values as null. Is there any specific reason for this null value in retrived events?