Haruki Okada created KAFKA-12261: ------------------------------------ Summary: auto.offset.reset should be earliest by default Key: KAFKA-12261 URL: https://issues.apache.org/jira/browse/KAFKA-12261 Project: Kafka Issue Type: Improvement Affects Versions: 2.7.0 Reporter: Haruki Okada
As of now, auto.offset.reset of ConsumerConfig is "latest" by default. This could be a pitfall that causes message delivery loss when we split topic's partitions like below: Say we have a topic-X which have only 1 partition. # split topic-X to 2 partitions by kafka-topics.sh --alter --topic topic-X --partitions 2 (topic-X-1 is added) # producer knows that new partitions are added by refreshing metadata. starts to produce to topic-X-1 # bit later, consumer knows that new partitions are added and triggering consumer rebalance, then starts consuming topic-X-1 ** upon starting consumption, it resets its offset to log-end-offset If the producer sent several records before 3, they could be not-delivered to the consumer. This behavior isn't preferable in most cases, so auto.offset.reset should be set to "earliest" by default to avoid this pitfall. -- This message was sent by Atlassian Jira (v8.3.4#803005)