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  5. 6.1.2 Modifying topics

6.1.2 Modifying topics

You can change the configuration or partitioning of a topic using the same topic tool.

To add partitions you can do

  > bin/kafka-topics.sh --bootstrap-server broker_host:port --alter --topic my_topic_name \
        --partitions 40

Be aware that one use case for partitions is to semantically partition data, and adding partitions doesn’t change the partitioning of existing data so this may disturb consumers if they rely on that partition. That is if data is partitioned by hash(key) % number_of_partitions then this partitioning will potentially be shuffled by adding partitions but Kafka will not attempt to automatically redistribute data in any way.

To add configs:

  > bin/kafka-configs.sh --bootstrap-server broker_host:port --entity-type topics --entity-name my_topic_name --alter --add-config x=y

To remove a config:

  > bin/kafka-configs.sh --bootstrap-server broker_host:port --entity-type topics --entity-name my_topic_name --alter --delete-config x

And finally deleting a topic:

  > bin/kafka-topics.sh --bootstrap-server broker_host:port --delete --topic my_topic_name

Kafka does not currently support reducing the number of partitions for a topic.

Instructions for changing the replication factor of a topic can be found here.