How to produce messages to selected partition using kafka-console-producer?

Question

According to the Kafka documentation:

The producer is responsible for choosing which message to assign to which partition within the topic.

Answer 1

By now, the ConsoleProducer seems to support writing keyed messages to the topic. Kafka will use the hash of the key to distribute the message into partitions, at least with the default behaviour.

Currently, the default separator is \t, so entering key[\t]message will distribute it amongst partitions:

key1    a-message

The separator can be changed by providing the key.separator configuration, for example:

kafka-console-producer --broker-list localhost:9092,localhost:9093 \
  --topic mytopic --property key.separator=,

Send messages like this:

key2,another-message

I have tested this with the default tab and a custom seperator successfuly. The messages were distributed to two separate partitions.