Github user tzulitai commented on a diff in the pull request: https://github.com/apache/flink/pull/2509#discussion_r89365136 --- Diff: flink-streaming-connectors/flink-connector-kafka-0.8/src/main/java/org/apache/flink/streaming/connectors/kafka/internals/Kafka08Fetcher.java --- @@ -139,24 +143,65 @@ public void runFetchLoop() throws Exception { PeriodicOffsetCommitter periodicCommitter = null; try { - // read offsets from ZooKeeper for partitions that did not restore offsets - { - List<KafkaTopicPartition> partitionsWithNoOffset = new ArrayList<>(); - for (KafkaTopicPartitionState<TopicAndPartition> partition : subscribedPartitions()) { - if (!partition.isOffsetDefined()) { - partitionsWithNoOffset.add(partition.getKafkaTopicPartition()); - } + List<KafkaTopicPartition> partitionsWithNoOffset = new ArrayList<>(); + for (KafkaTopicPartitionState<TopicAndPartition> partition : subscribedPartitions()) { + if (!partition.isOffsetDefined()) { + partitionsWithNoOffset.add(partition.getKafkaTopicPartition()); } + } + + if (partitionsWithNoOffset.size() == subscribedPartitions().length) { + // if all partitions have no initial offsets, that means we're starting fresh without any restored state + switch (startupMode) { + case EARLIEST: + LOG.info("Setting starting point as earliest offset for partitions {}", partitionsWithNoOffset); + + for (KafkaTopicPartitionState<TopicAndPartition> partition : subscribedPartitions()) { + partition.setOffset(OffsetRequest.EarliestTime()); + } + break; + case LATEST: + LOG.info("Setting starting point as latest offset for partitions {}", partitionsWithNoOffset); + + for (KafkaTopicPartitionState<TopicAndPartition> partition : subscribedPartitions()) { + partition.setOffset(OffsetRequest.LatestTime()); + } + break; + default: + case GROUP_OFFSETS: + LOG.info("Using group offsets in Zookeeper of group.id {} as starting point for partitions {}", + kafkaConfig.getProperty("group.id"), partitionsWithNoOffset); + + Map<KafkaTopicPartition, Long> zkOffsets = zookeeperOffsetHandler.getCommittedOffsets(partitionsWithNoOffset); + for (KafkaTopicPartitionState<TopicAndPartition> partition : subscribedPartitions()) { + Long offset = zkOffsets.get(partition.getKafkaTopicPartition()); + if (offset != null) { + // the committed offset in ZK represents the next record to process, + // so we subtract it by 1 to correctly represent internal state + partition.setOffset(offset - 1); + } else { + // if we can't find an offset for a partition in ZK when using GROUP_OFFSETS, + // we default to "auto.offset.reset" like the Kafka high-level consumer + LOG.warn("No group offset can be found for partition {} in Zookeeper;" + + " resetting starting offset to 'auto.offset.reset'", partition); + + partition.setOffset(invalidOffsetBehavior); + } + } + } + } else if (partitionsWithNoOffset.size() > 0 && partitionsWithNoOffset.size() < subscribedPartitions().length) { --- End diff -- I was adding this as a preparation for the kafka partition discovery task. But it'd probably make sense to remove it for this PR to avoid confusion.
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