Use of AggregateFunction's merge() method

Posted by Ken Krugler on
URL: http://deprecated-apache-flink-user-mailing-list-archive.369.s1.nabble.com/Use-of-AggregateFunction-s-merge-method-tp19978.html

I’m trying to figure out when/why the AggregateFunction.merge() method is called in a streaming job, to ensure I’ve implemented it properly.

The documentation for AggregateFunction says "Merging intermediate aggregates (partial aggregates) means merging the accumulators.”

But that sounds more like a combiner in batch processing, not streaming.

From the code, it seems like this could be called if a MergingWindowAssigner is used, right?

And is there any other situation in streaming where merge() could be called?

Thanks,

— Ken

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