Hi Oleg, Could you be more specific on what do you mean by "for events of last n seconds(time units in general) for every incoming event."?
Do you mean that you have a stream of parallelism 1 and you want for each incoming element to have your function fire with input the event itself and all the events that arrived within the last N time units? If this is the case, you can use a dummy key to key your stream to have access to keyed state, then use Map State with key being the timestamp and value being a list of the already seen elements with that timestamp and whenever an element arrives, you can register a timer to fire N time units in the future. Then, when the timer fires, you can iterate over the map, fetch the elements you are interested in, and clean-up whatever you will not need anymore. For an example you could look at [1]. I hope this helps, Kostas [1] https://ci.apache.org/projects/flink/flink-docs-stable/dev/stream/operators/process_function.html On Tue, Feb 11, 2020 at 11:18 PM Fanbin Bu <fanbin...@coinbase.com> wrote: > > can u do > RANGE BETWEEN INTERVAL '1' SECOND PRECEDING AND CURRENT ROW? > > On Tue, Feb 11, 2020 at 12:15 PM oleg <olegpel...@gmail.com> wrote: >> >> Hi Community, >> >> I do streaming in event time and I want to preserve ordering and late >> events. I have a use case where I need to fire an aggregation function >> for events of last n seconds(time units in general) for every incoming >> event. >> >> It seems to me that windowing is not suitable since it may be expressed >> either in time or in events count, not "last n seconds for each single >> event". >> >> Is there an idiomatic way to do this? Any examples or help are >> appreciated. Thanks in advance. >> >> >> Best regards, >> >> Oleg Bonar >>
