Thank you Aljoscha for your quick response. Best, Yassine
2016-11-02 12:30 GMT+01:00 Aljoscha Krettek <aljos...@apache.org>: > Hi Yassine, > > regarding 1. The close() method of the RichFoldFunction will only be > called at the very end of your streaming job, so in practise it will never > be called. This is there because of batch jobs, where you have an actual > end in your processing. > > regarding 2. I'm afraid you came across a bug: https://issues.apache. > org/jira/browse/FLINK-3869. We can't change this right now because we > cannot break API instability but right at the end of this issue I'm > proposing a different solution that we'll hopefully get in for the next > release. > > Cheers, > Aljoscha > > On Wed, 2 Nov 2016 at 10:42 Yassine MARZOUGUI <y.marzou...@mindlytix.com> > wrote: > >> Hi all, >> >> I have a couple questions about FoldFunction and WindowFunction: >> >> 1. When using a RichFoldFunction after a window as in >> keyedStream.window().fold(new RichFoldFunction()), is the close() method >> called after each window or after all the windows for that key are fired? >> >> 2. When applying a FoldFunction to a window followed by a WindowFunction >> via apply >> <https://ci.apache.org/projects/flink/flink-docs-master/api/java/org/apache/flink/streaming/api/datastream/WindowedStream.html#apply-R-org.apache.flink.api.common.functions.FoldFunction-org.apache.flink.streaming.api.functions.windowing.WindowFunction->(R >> initialValue, >> FoldFunction >> <https://ci.apache.org/projects/flink/flink-docs-master/api/java/org/apache/flink/api/common/functions/FoldFunction.html> >> <T >> <https://ci.apache.org/projects/flink/flink-docs-master/api/java/org/apache/flink/streaming/api/datastream/WindowedStream.html> >> ,R> foldFunction, WindowFunction >> <https://ci.apache.org/projects/flink/flink-docs-master/api/java/org/apache/flink/streaming/api/functions/windowing/WindowFunction.html> >> <R,R,K >> <https://ci.apache.org/projects/flink/flink-docs-master/api/java/org/apache/flink/streaming/api/datastream/WindowedStream.html> >> ,W >> <https://ci.apache.org/projects/flink/flink-docs-master/api/java/org/apache/flink/streaming/api/datastream/WindowedStream.html> >> > function), why should the output of the WindowFunction be of the same >> type as the input? It would be practical to have a different output type >> sometimes, for example one would fold tuples in the FoldFunction and then >> process the (only) aggregated tuple in the Window function and emit an >> Integer. >> >> Best, >> Yassine >> >
