What is the role and purpose of a consumer group in Apache Kafka architecture?

In Apache Kafka, a consumer group is a logical grouping of one or more consumers that jointly read data from topics.

Main roles and purposes of a consumer group:

• Parallel processing: Each consumer in the group reads data from a unique set of topic partitions, allowing for scalable message processing.

• Delivery guarantee: Kafka guarantees that each message will be processed by exactly one consumer in the group.

• Load balancing: When consumers are added or removed from the group, partitions are redistributed among them.

• Progress tracking: Each consumer group stores offsets (read positions) for each partition, enabling continuation of reading from the last processed message.

Thus, a consumer group ensures scalability, fault tolerance, and simplifies data consumption management from Kafka.