Hi Abdul,
Flink provides no ordering guarantees on the elements within a window.
The only “order” it guarantees is that the results referring to window-1 are
going to be emitted before those of window-2 (assuming that window-1 precedes
window-2).
Thanks,
Kostas
> On Jan 5, 2017, at 11:57 AM, Abdul Salam Shaikh <abd.salam.sha...@gmail.com>
> wrote:
>
> Hi,
>
> I am using a JSON file as the source for the streaming (in the ascending
> order of the field Umlaufsekunde)which has events as follows:
>
> {"event":[{"Umlaufsekunde":115}]}
> {"event":[{"Umlaufsekunde":135}]}
> {"event":[{"Umlaufsekunde":135}]}
> {"event":[{"Umlaufsekunde":145}]}
> {"event":[{"Umlaufsekunde":155}]}
> {"event":[{"Umlaufsekunde":155}]}
> {"event":[{"Umlaufsekunde":185}]}
> {"event":[{"Umlaufsekunde":195}]}
> {"event":[{"Umlaufsekunde":195}]}
> {"event":[{"Umlaufsekunde":205}]}
> {"event":[{"Umlaufsekunde":245}]}
>
> However, when I try to print the stream, it is unordered as given below:
> 1> (115,null,1483517983252,1190) -- The first value indicating Umlaufsekunde
> 2> (135,null,1483517984877,1190)
> 2> (155,null,1483517986861,1190)
> 4> (145,null,1483517985752,1190)
> 3> (135,null,1483517985424,1190)
> 4> (195,null,1483517990736,1190)
> 4> (255,null,1483517997424,1190)
> 2> (205,null,1483517991518,1190)
> 2> (275,null,1483517999330,1190)
> 2> (385,null,1483518865371,1190)
> 2> (395,null,1483518866840,1190)
> 1> (155,null,1483517986533,1190)
> 4> (285,null,1483518000189,1190)
> 4> (395,null,1483518866231,1190)
>
> I have also tried using the Timestamps and Watermarks but no luck as follows:
>
> public class TimestampExtractor implements
> AssignerWithPeriodicWatermarks<Tuple5<String, Long, List<Lane>, Long, Long>>{
>
> private long currentMaxTimestamp;
>
> @Override
> public Watermark getCurrentWatermark() {
> return new Watermark(currentMaxTimestamp);
> }
>
> @Override
> public long extractTimestamp(Tuple5<String, Long> element, long
> previousElementTimestamp) {
> long timestamp = element.getField(1);
> currentMaxTimestamp = timestamp;
> return currentMaxTimestamp;
> }
>
> }
>
> Could anyone suggest how do I handle this problem for the arrival of events
> in order ?
>
> Thanks!
>
>
