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Posted to user@flink.apache.org by 邓俊华 <de...@startdt.com> on 2018/01/15 02:29:50 UTC
回复:How can I count the element in datastream
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 <tz...@apache.org>发送时间:2018年1月12日(星期五) 22:37收件人:user <us...@flink.apache.org>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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