Hi there, The new feature in Flink 1.11 will provide us the Unaligned Checkpoint which means a operator subtask does not need to wait all the Checkpoint barrier and will not block some channels. As the Checkpoint barrier is the key mechanism for Exactly Once guarantee, I am not sure Unaligned Checkpoint could still achieve Exactly Once guarantee or only AT Least Once?
FLIP-76<https://cwiki.apache.org/confluence/display/FLINK/FLIP-76%3A+Unaligned+Checkpoints> : Unaligned checkpoints will initially be an optional feature. After collecting experience and implementing all necessary extensions, unaligned checkpoint will probably be enabled by default for exactly once. What's more, in the following two configs, Config 1 env.getCheckpointConfig().enableUnalignedCheckpoints(); Config 2 checkpointCfg.setCheckpointingMode(CheckpointingMode.AT_LEAST_ONCE); Does Config 2 use a even simpler way for Checkpoint than Unaligned Checkpoint? Hope for replies! Weizheng
