Hi, I would interpret this as: the reduce produces an output for every new reduce call, emitting the updated value. There is no need for a window because it kicks in on every single invocation.
Best, Stefan > Am 31.12.2017 um 22:28 schrieb M Singh <mans2si...@yahoo.com>: > > Hi: > > Apache Flink documentation > (https://ci.apache.org/projects/flink/flink-docs-release-1.4/dev/stream/operators/index.html) > indicates that a reduce function on a KeyedStream as follows: > > A "rolling" reduce on a keyed data stream. Combines the current element with > the last reduced value and emits the new value. > > A reduce function that creates a stream of partial sums: > keyedStream.reduce(new ReduceFunction<Integer>() { > @Override > public Integer reduce(Integer value1, Integer value2) > throws Exception { > return value1 + value2; > } > }); > > The KeyedStream is not windowed, so when does the reduce function kick in to > produce the DataStream (ie, is there a default time out, or collection size > that triggers it, since we have not defined any window on it). > > Thanks > > Mans
