Re: Apache Flink - Question about rolling window function on KeyedStream

2018-01-04 Thread M Singh
Hi Fabian: Thanks for your answer - it is starting to make sense to me now. On Thursday, January 4, 2018 12:58 AM, Fabian Hueske wrote: Hi, the ReduceFunction holds the last emitted record as state. When a new record arrives, it reduces the new record and last emitted record, updates

Re: Apache Flink - Question about rolling window function on KeyedStream

2018-01-04 Thread Fabian Hueske
Hi, the ReduceFunction holds the last emitted record as state. When a new record arrives, it reduces the new record and last emitted record, updates its state, and emits the new result. Therefore, a ReduceFunction emits one output record for each input record, i.e., it is triggered for each input

Re: Apache Flink - Question about rolling window function on KeyedStream

2018-01-03 Thread M Singh
Hi Stefan: Thanks for your response. A follow up question - In a streaming environment, we invoke the operation reduce and then output results to the sink. Does this mean reduce will be executed once on every trigger per partition with all the items in each partition ? Thanks On Wednesday

Re: Apache Flink - Question about rolling window function on KeyedStream

2018-01-03 Thread Stefan Richter
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 : > > Hi: > > Apache Flink documentation >

Apache Flink - Question about rolling window function on KeyedStream

2017-12-31 Thread M Singh
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 emit