Looping in Kostas and Aljoscha who should know what's the expected behaviour here ;)
On 11 November 2016 at 16:17:23, Petr Novotnik (petr.novot...@firma.seznam.cz) wrote: > Hello, > > I'm struggling to understand the following behaviour of the > `WindowOperator` and would appreciate some insight from experts: > > In particular I'm thinking about the following hypothetical data flow: > > input.keyBy(..) > .window(TumblingEventTimeWindows.of(..)) > .apply(..) > ... > .keyBy(..) > .window(CustomWindowAssignerUsingATriggerBasedOnTheElementsStamp) > .apply(..) > > When the first window operator fires a window based on the timer, the > emitted elements are assigned a timestamp which equals > `window.maxTimestamp()`. This stamp is then available in the second > window operator's trigger through the `onElement` method. So far so good. > > However, when using `ContinuousEventTimeTrigger` (simply put when firing > the window multiple times at different times in its lifecycle) in the > first window operator, _all_ of the elements of this window - no matter > whether fired as a partial or the final window result - will arrive with > the same stamp in the (downstream) operators. > > This make it practically impossible to use again > `ContinuousEventTimeTrigger` (or similar) in the second window operator > to achieve "early firing" again. > > This is surprising. I would expect the elements to be assigned the stamp > of the timer which fired them (which will be window#maxTimestamp() for > `TumblingEventTimeWindows`). Is there any particular reason for the > unconditional assignment to `window.maxTimestamp()`? > > Many thanks in advance, > P. >
