Apache Kafka order of messages with multiple partitions

Question

As per Apache Kafka documentation, the order of the messages can be achieved within the partition or one partition in a topic. In this case, what is the parallelism benefit

Answer 1

Well, this is an old thread, but still relevant, hence decided to share my view.

I think this question is a bit confusing.

If you need strict ordering of messages, then the same strict ordering should be maintained while consuming the messages. There is absolutely no point in ordering message in queue, but not while consuming it. Kafka allows best of both worlds. It allows ordering the message within a partition right from the generation till consumption while allowing parallelism between multiple partition. Hence, if you need

Absolute ordering of all events published on a topic, use single partition. You will not have parallelism, nor do you need (again parallel and strict ordering don't go together).

Go for multiple partition and consumer, use consistent hashing to ensure all messages which need to follow relative order goes to a single partition.