Hi Xingbo, Thank you for your valuable suggestions.
Indeed, we need to provide clearer abstractions for StateDescriptor and State APIs, I have updated the FLIP accordingly. Looking forward to your feedbacks! Best, Shuiqiang > 在 2020年12月14日，上午11:27，Xingbo Huang <hxbks...@gmail.com> 写道： > > Thanks Shuiqiang for starting this discussion. > > Big +1 for this feature. State access support can further improve the > functionality of our existing Python DataStream. > > I have 2 comments regarding to the design doc: > > a) I think that `StateDescriptor` needs to hold the variable `typeInfo` > instead of letting each implementation class hold `typeInfo` itself.For > example, `ListStateDescriptor` does not hold `elem_type_info`, but passes > `ListTypeInfo(elem_type_info)` to the construct method of `StateDescriptor`. > > b) I think we need to add the `MergingState` and `AppendingState` > interfaces, and then extract the `get` and `add` methods from `ListState`, > `AggregatingState`, and `ReducingState` into `AppendingState`. Then let > `ListState`, `AggregatingState` and `ReducingState` inherit `MergingState`. > > Best, > Xingbo > > Shuiqiang Chen <acqua....@gmail.com> 于2020年12月11日周五 下午9:44写道： > >> Hi devs, >> >> In FLIP-130, we have already supported Python DataStream stateless APIs so >> that users are able to perform some basic data transformations. To >> implement more complex data processing, we need to provide state access >> support. So I would propose to add state access APIs in Python DataStream >> API to support stateful operations on a KeyedStream. More details are in >> the FLIP wiki page [1]. >> >> Any feedback will be highly appreciated! >> >> [1] >> >> https://cwiki.apache.org/confluence/display/FLINK/FLIP-153%3A+Support+state+access+in+Python+DataStream+API >> >> Best, >> Shuiqiang >>
