Posted by
Yuta Morisawa on
URL: http://deprecated-apache-flink-user-mailing-list-archive.369.s1.nabble.com/How-to-use-Lo-level-Joins-API-tp29218p29220.html
Hi Yun
Thank you for replying.
> Have you set a default value for the state ?
Actually, the constructor of the ValueStateDescriptor with default value
is deprecated so I don't set it.
The problem occurs when the stream1 comes first.
I made sure the 'ValueState data' has data from stream1 with the IDE
debugger but in spite of that, processElement2 can't access it.
On 2019/08/07 11:43, Yun Gao wrote:
> Hi Yuta,
> Have you set a default value for the state ? If the state did not
> have a default value and the records from stream2 comes first for a
> specific key, then the state would never be set with a value, thus the
> return value will be null.
>
> Best,
> Yun
>
>
> ------------------------------------------------------------------
> From:Yuta Morisawa <
[hidden email]>
> Send Time:2019 Aug. 7 (Wed.) 08:56
> To:user <
[hidden email]>
> Subject:How to use Lo-level Joins API
>
> Hi
>
> I am trying to use low-level joins.
> According to the doc, the way is creating a state and access it from
> both streams, but I can't.
>
>
https://ci.apache.org/projects/flink/flink-docs-release-1.8/dev/stream/operators/process_function.html>
> This is a snippet of my code.
> It seems that the processElement1,2 have different ValueStates so that
> v1 in processElement2 is always null.
>
> ---
> stream1.connect(stream2).keyBy(0,0).process(new MyCPF());
>
> public class MyCPF extends CoProcessFunction{
> ValueState data;
>
> processElement1(v1){
> data.update(v1);
> }
>
> processElement2(v2){
> v1 = data.value() // v1 is always null
> out.collect(v1 + v2)
> }
>
> open(){
> data = getRuntimeContext().getState(descriptor);
> }
>
> }
> ---
>
> Can you tell me the collect way of the low-level joins and send me a
> sample code if you have?
>
> --
> Thank you
> Yuta
>
>
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