If I'm understanding correctly, you want something liked "tumbling-session" windows. Session windows [1] do exactly what you describe but are only evaluated after a certain period of inactivity, but you want to evaluate the window every X minutes after the first element for a key arrived, right? I think Gyula (cc'd) did something similiar for [2]. Maybe he can share his code?
[1] https://ci.apache.org/projects/flink/flink-docs-master/apis/streaming/windows.html#session-windows [2] https://techblog.king.com/rbea-scalable-real-time-analytics-king/ On Mon, Aug 15, 2016 at 7:05 PM, dan bress <danbr...@gmail.com> wrote: > I am interesting in writing a custom tumbling window assigner to do the > following: > > As soon as the first event for that keyed stream comes in, create a window > from that point going forward N milli seconds. Is it possible to do that > using flink? What I want to do is get all events that occurred in a 5 > minute period, where the period starts with the time of the first event. > Flink's current tumbling time windows would be locked to the top of 0, 5, > 10, 15 minutes, which doesn't work well for me if the first event for a key > comes in at 14 minutes, because the window will be triggered at 15 minutes, > instead of at 19 minutes. > > Looking at the interface for WindowAssigner it doesn't look like I have > enough information to do what I need. > > I would need to know the key, since each keyed stream could have a > different start time, and I would need to be able to store some state about > what the start time is for each key, like a Map of > StreamKey->FirstEventTime. > > Do you have any suggestions for assigning a window that starts with the > time of the first event in that keyed stream, and ends N minutes after that? > > Thanks! > > Dan
