Hi Viktor, I’m starting to wonder what exactly “duplicate” means in this context. Can you elaborate?
In case it helps, with your window definition, if I send a record with timestamp 20, it would actually belong to three different windows: [0,30) [10,40) [20,50) Because of this, you would (correctly) see three output records for that one input, but the outputs wouldn’t be “duplicates” properly, because they’d have different keys: Input: Key1: Val1 @ timestamp:20 Output: Windowed<Window(0,30),Key1>: 1 Windowed<Window(10,40),Key1>: 1 Windowed<Window(20,50),Key1>: 1 Any chance that explains your observation? Thanks, John On Thu, Jan 16, 2020, at 10:18, Viktor Markvardt wrote: > Hi John, > > Thanks for answering my questions! > I observe behavior which I can not understand. > The code is working, but when delay between records larger then window > duration I receive duplicated records. > With the code below I received duplicated records in the output kstream. > Count of duplicate records is always 3. If I change duration/advanceBy > count of duplicated records is changing also. > Do you have any ideas why duplicated records are received in the output > kstream? > > KStream<String, String> windowedStream = source > .groupByKey() > > .windowedBy(TimeWindows.of(Duration.ofSeconds(30)).grace(Duration.ZERO).advanceBy(Duration.ofSeconds(10))) > .count() > > .suppress(Suppressed.untilWindowCloses(Suppressed.BufferConfig.unbounded())) > .toStream(); > > > Best regards, > Viktor Markvardt > > чт, 16 янв. 2020 г. в 04:59, John Roesler <vvcep...@apache.org>: > > > Hi Viktor, > > > > I’m not sure why you get two identical outputs in response to a single > > record. Regardless, since you say that you want to get a single, final > > result for the window and you expect multiple inputs to the windows, you > > need Suppression. > > > > My guess is that you just sent one record to try it out and didn’t see any > > output? This is expected. Just as the window boundaries are defined by the > > time stamps of the records, not by the current system time, suppression is > > governed by the timestamp of the records. I.e., a thirty-second window is > > not actually closed until you see a new record with a timestamp thirty > > seconds later. > > > > Maybe try just sending a sequence of updates with incrementing > > timestamps. If the first record has timestamp T, then you should see an > > output when you pass in a record with timestamp T+30. > > > > Important note: there is a built-in grace period that delays the output of > > final results after the window ends. For complicated reasons, the default > > is 24 hours! So you would actually not see an output until you send a > > record with timestamp T+30+(24 hours) ! I strongly recommend you set the > > grace period on TimeWindows to zero for your testing. You can increase it > > later if you want to tolerate some late-arriving records. > > > > Thanks, > > -John > > > > On Tue, Jan 14, 2020, at 10:41, Viktor Markvardt wrote: > > > Hi, > > > > > > My name is Viktor. I'm currently working with Kafka streams and have > > > several questions about Kafka and I can not find answers in the official > > > docs. > > > > > > 1. Why suppress functionality does not work with Hopping windows? How to > > > make it work? > > > > > > Example of the code: > > > > > > KStream<String, String> finalStream = source > > > .groupByKey() > > > > > > > > .windowedBy(TimeWindows.of(Duration.ofSeconds(30)).advanceBy(Duration.ofSeconds(10))) > > > .reduce((aggValue, newValue) -> newValue, > > > Materialized.with(Serdes.String(), Serdes.String())) > > > > > > > > .suppress(Suppressed.untilWindowCloses(Suppressed.BufferConfig.unbounded())) > > > .toStream(); > > > > > > finalStream.print(Printed.toSysOut()); > > > finalStream.to(outputTopic); > > > > > > After I run the code above - output stream is empty. There were no > > > errors/exceptions. > > > NOTE: With Tumbling Window the code working as expected. > > > Maybe I simply use it incorrectly? > > > > > > 2. Why with Hopping windows (without suppress) there are duplicates in > > the > > > output stream? > > > E.g., I send one record in the input kstream with Hopping window > > > (duration=30s, advanceBy=2s) but get two same records (duplicate) in the > > > output kstream. > > > Is that an expected behavior? If so, how can I filter/switch off these > > > duplicates? > > > > > > 3. Mainly I'm trying to solve this problem: > > > I have kstream with events inside and events can be repeated > > (duplicates). > > > In the output kstream I would like to receive only unique events for the > > > last 24 hours (window duration) with 1 hour window overlay (window > > > advanceBy). > > > Could you recommend me any examples of code or docs please? > > > I have already read official docs and examples but it was not enough to > > get > > > full understanding of how I can achieve this. > > > > > > Best regards, > > > Viktor Markvardt > > > > > >
