How to read data using Kafka Consumer API from beginning?

Question

Please can anyone tell me how to read messages using the Kafka Consumer API from the beginning every time when I run the consumer.

Answer 1

To always read from offset 0 without creating new groupId everytime.

    // ... Assuming the props have been set properly.
    // ... enable.auto.commit and auto.offset.reset as default

    KafkaConsumer consumer = new KafkaConsumer<>(props);
    consumer.subscribe(Collections.singletonList(topic));
    consumer.poll(0);  // without this, the assignment will be empty. 
    consumer.assignment().forEach(t -> {
        System.out.printf("Set %s to offset 0%n", t.toString());
        consumer.seek(t, 0);
    });
    while (true) {
     // ... consumer polls messages as usual.
    }