Hi Zhen Li, You can control when a windowed stream emits data with "Triggers". See: https://ci.apache.org/projects/flink/flink-docs-stable/dev/stream/operators/windows.html#triggers
Flink comes with a couple of default triggers, but you can also create your own by implementing https://ci.apache.org/projects/flink/flink-docs-stable/api/java/org/apache/flink/streaming/api/windowing/triggers/Trigger.html . Note that this does not change the window, but just causes the windowedstream to emit intermediate results to the next operator. Does this answer your question? Cheers, Niels On Wed, Oct 17, 2018 at 12:34 PM zhen li <lizhenm...@hotmail.com> wrote: > Hi all: > How can I trigger the window manually in fold operator or incremental > aggregation? For example, when some conditions is meet，althouth the count > window or time window is not reach
