Hi all, Recently, I noticed that the split/select methods in DataStream API have been marked as deprecated since 1.7.2 and 1.8.0 (the related JIRA issue FLINK-11084 <https://issues.apache.org/jira/browse/FLINK-11084>).
Although the two methods can be replaced by the more powerful side output feature[1], I still doubt whether we should really remove them in the future. 1. From semantics, the split/select is the reverse operation to the union transformation. Without them, the DataStream API seems to be missing a piece. 2. From accessibility, the side output only works for process functions, which means it forces the user to dive into a lower API. According to FLINK-11084 <https://issues.apache.org/jira/browse/FLINK-11084>, there exist some problems with the current implementation of the two methods. Maybe we should fix the problems and re-active them again. Or if they really need to be deprecated, we should at least mark the corresponding documentation for that : ) What do you think? Best, Xingcan [1] https://ci.apache.org/projects/flink/flink-docs-master/dev/stream/side_output.html <https://ci.apache.org/projects/flink/flink-docs-master/dev/stream/side_output.html>
