Aljoschae, exactly. I'm assuming I don't want to maintain state in the window assigner? What would you do if you wanted to solve this problem? On Tue, Aug 16, 2016 at 7:29 AM Aljoscha Krettek <aljos...@apache.org> wrote:
> Hi, > the problem with using session windows is that you don't know which one is > the "first element" unless you keep some sort of state in the > WindowAssigner, right? Otherwise, the first element could spawn a window > and the non-first elements could have windows of length 0 that get merged > into the first window of the length that you desired. > > Cheers, > Aljoschae > > On Tue, 16 Aug 2016 at 11:54 Ufuk Celebi <u...@apache.org> wrote: > > > 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 > > >
