What is a consumer group in Kafka and how is it related to partitions?

A consumer group in Kafka is a group of consumers that jointly read data from a topic. Each consumer in the group receives a unique set of topic partitions to process, which ensures parallelism and scalability.

Connection to partitions:

• A topic in Kafka is divided into partitions.
• Each partition can only be read by one consumer from one group at a time.
• If there are more consumers than partitions, some consumers will be idle.
• If there are fewer consumers than partitions, some consumers will read multiple partitions.

Thus, a consumer group allows distributing the load across partitions and ensures balanced message consumption.