How can I count the element in datastream

[邓俊华]

hi,

How can I count the element in datastream? I don't want the keyBy().

[Tzu-Li (Gordon) Tai]

Hi!

Do you mean that you want to count all elements across all partitions of a
DataStream?
To do that, you'll need to transform the DataStream with an operator of
parallelism 1, e.g.

DatatStream<String> stream = ...;
stream.map(new CountingMap<>()).setParallelism(1);

Cheers,
Gordon



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[邓俊华]

Yes, I want count all the elements. But I can't do cumulative.

eg：

   

distinctOrder.map(new MapFunction<Order, Object>() {

    @Override
    public Object map(Order value) throws Exception {
       
        return null;
    }
}).setParallelism(1).print();

------------------------------------------------------------------

发件人：Tzu-Li (Gordon) Tai <[hidden email]>

发送时间：2018年1月12日(星期五) 22:37

收件人：user <[hidden email]>

主　题：Re: How can I count the element in datastream

Hi!

Do you mean that you want to count all elements across all partitions of a
DataStream?
To do that, you'll need to transform the DataStream with an operator of
parallelism 1, e.g.

DatatStream<String> stream = ...;
stream.map(new CountingMap<>()).setParallelism(1);

Cheers,
Gordon



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