@Aljoscha Krettek<mailto:aljos...@apache.org> , got it and thanks for your clarification.
Best Yun Tang 获取 Outlook for Android<https://aka.ms/ghei36> ________________________________ From: Aljoscha Krettek <aljos...@apache.org> Sent: Thursday, January 16, 2020 8:40:57 PM To: dev@flink.apache.org <dev@flink.apache.org> Subject: Re: [DISCUSS] Make AppendingState#add refuse to add null element This is mostly a remnant from the previous state API, see [1] for reference. The behaviour was basically copied to the new state implementations, which was a mistake, in hindsight. Also see [2] where I added AppendingState, here I also didn't document any special null behaviour. Best, Aljoscha [1] https://github.com/apache/flink/commit/caf46728045c0b886e6d4ec0aa429a830740a391 [2] https://github.com/apache/flink/commit/6cd8ceb10c841827cf89b74ecf5a0495a6933d53 On 16.01.20 04:13, Yun Tang wrote: > +1 for unifying the behavior of AppendingState#add . > > However, I have concern for the usage of window reducing function [1], I'm > not sure whether user would rely on processing StreamRecord(null) to clear > state. As you can see, user could not see the reducing window state directly, > and the only way to communicate with state is via processing records. > > I'm not sure whether this is by design, @Aljoscha > Krettek<mailto:aljos...@apache.org> would you please share the initial idea > when introducing this for the first time? > > > [1] > https://ci.apache.org/projects/flink/flink-docs-stable/dev/stream/operators/windows.html#reducefunction > > Best > Yun Tang > > ________________________________ > From: Yu Li <car...@gmail.com> > Sent: Thursday, January 9, 2020 14:09 > To: dev <dev@flink.apache.org> > Subject: Re: [DISCUSS] Make AppendingState#add refuse to add null element > > +1 for unifying the behavior to refusing adding null element. Nice catch > and thanks for bringing up the discussion! > > Best Regards, > Yu > > > On Wed, 8 Jan 2020 at 22:50, Aljoscha Krettek <aljos...@apache.org> wrote: > >> Hi, >> >> As I said in the discussion on the Jira issue, I’m in favour of this >> change! >> >> This is the Jira Issue, for reference: >> https://issues.apache.org/jira/browse/FLINK-15424 >> >> Best, >> Aljoscha >> >>> On 8. Jan 2020, at 15:16, Congxian Qiu <qcx978132...@gmail.com> wrote: >>> >>> Dear All >>> >>> >>> Currently, we found the implementations of AppendingState#add are not the >>> same, taking some as example: >>> >>> - HeapReducingState will clear state if add null element >>> - RocksDBReducingState will add null element if serializer can >> serialize >>> null >>> - Both HeapListState and RocksDBListState refuse to add null element ― >>> will throw NullPointException >>> >>> >>> we think this need to be fixed, and possible solutions include: >>> >>> 1. Respect the current java doc, which said “If null is passed in, the >>> state value will remain unchanged” >>> 2. Make all AppendingState#add refuse to add null element >>> >>> >>> We propose to apply the second solution, following the recommendation in >>> Guava[1]. >>> >>> >>> Would love to hear your thoughts. Thanks. >>> >>> >>> Regards, >>> >>> Congxian >>> >>> >>> [1] https://github.com/google/guava/wiki/UsingAndAvoidingNullExplained >> >> >
