Personally I prefer 3) to keep split/select and correct the behavior. I feel side output is kind of overkill for such a primitive function, and I prefer simple APIs like split/select.
Hao Sun On Thu, Jul 4, 2019 at 11:20 AM Xingcan Cui <xingc...@gmail.com> wrote: > Hi folks, > > Two weeks ago, I started a thread [1] discussing whether we should discard > the split/select methods (which have been marked as deprecation since v1.7) > in DataStream API. > > The fact is, these methods will cause "unexpected" results when using > consecutively (e.g., ds.split(a).select(b).split(c).select(d)) or > multi-times on the same target (e.g., ds.split(a).select(b), > ds.split(c).select(d)). The reason is that following the initial design, > the new split/select logic will always override the existing one on the > same target operator, rather than append to it. Some users may not be > aware of that, but if you do, a current solution would be to use the more > powerful side output feature [2]. > > FLINK-11084 <https://issues.apache.org/jira/browse/FLINK-11084> added > some restrictions to the existing split/select logic and suggest to > replace it with side output in the future. However, considering that the > side output is currently only available in the process function layer and > the split/select could have been widely used in many real-world > applications, we'd like to start a vote andlisten to the community on how > to deal with them. > > In the discussion thread [1], we proposed three solutions as follows. All > of them are feasible but have different impacts on the public API. > > 1) Port the side output feature to DataStream API's flatMap and replace > split/select with it. > > 2) Introduce a dedicated function in DataStream API (with the "correct" > behavior but a different name) that can be used to replace the existing > split/select. > > 3) Keep split/select but change the behavior/semantic to be "correct". > > Note that this is just a vote for gathering information, so feel free to > participate and share your opinions. > > The voting time will end on *July 7th 17:00 EDT*. > > Thanks, > Xingcan > > [1] > https://lists.apache.org/thread.html/f94ea5c97f96c705527dcc809b0e2b69e87a4c5d400cb7c61859e1f4@%3Cdev.flink.apache.org%3E > <https://lists.apache.org/thread.html/f94ea5c97f96c705527dcc809b0e2b69e87a4c5d400cb7c61859e1f4@%3Cdev.flink.apache.org%3E> > [2] > 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> >
