THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
...
However, the mapping from a record or a key to the SplitID could be obscure to the user. For example, the data could be computed in Flink, then streaming to the Flink through an MQ, e.g., Kafka. In this example, neither the logic of partitioning partitioner nor the splitID is a public API for the users. This could be common under many scenarios. Therefore, it is hard and possibly meaningless for users to provide the "SplitSelector".
...