Satarupa, In my experience kafka has a 10k partition limit per topic. I don't think you are going to be able to get 1 million partitions to work on a single topic. A consumer would need to subscribe to listen to a kafka topic. You will probably need to have multiple consumer groups or multiple topics to handle that many consumers. I would recommend doing some research on other very large kafka setups. Consumers also talk directly to kafka in newer versions and shouldn't be talking to zookeeper unless you are using a very old version of kafka.
Tyler Monahan