Partitions

When sending messages to Kafka topics, we can choose whether or not to specify a key. If we don’t specify a key (i.e. it is set to null), Kafka’s default mechanism takes over to assign a partition. The default partitioner directs the message to one of the available partitions in a round-robin fashion.

If the key is specified but the partitioner class isn’t, then the default partitioner is employed. It will generate a hash of the ...