[jira] [Commented] (KAFKA-8504) Update Docs to explain how to use suppress() in more details

["John Roesler (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-8504?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16867907#comment-16867907 ] 

John Roesler commented on KAFKA-8504:
-------------------------------------

Hi Simone,

Sorry for the confusion. This sharp edge was and is a big concern for me, but I think we're "trapped" by the backward compatibility requirement.

I've tried to call it out whenever I discuss suppression, but it seems I missed it in the actual documentation. For reference, I think a special note callout should be added to this section of the docs, starting in 2.1: https://kafka.apache.org/21/documentation/streams/developer-guide/dsl-api.html#window-final-results

Is there anywhere else you think should be updated?

Thanks,
-John

> Update Docs to explain how to use suppress() in more details
> ------------------------------------------------------------
>
>                 Key: KAFKA-8504
>                 URL: https://issues.apache.org/jira/browse/KAFKA-8504
>             Project: Kafka
>          Issue Type: Improvement
>          Components: documentation, streams
>    Affects Versions: 2.2.1
>            Reporter: Simone Esposito
>            Priority: Minor
>              Labels: newbie
>
> Hi, I'm playing a bit with KafkaStream and the new suppress feature. I noticed that when using a {{TimeWindows}} without explicitly setting the grace {{suppress}} will not emit any message if used with {{Suppressed.untilWindowCloses.}}
> I look a bit into the code and from what I understood with this configuration {{suppress}} should use the {{grace}} setting of the {{TimeWindows}}. But since using {{TimeWindows.of(Duration)}} default the grace to {{-1}} and when getting the grace using the method {{TimeWindows.gracePeriodMs()}} in case of grace equals to -1 the return value is set to {{maintainMs() - size()}} I think that the end of window is not properly calculated. 
> Of course is possible to avoid this problem forcing the {{grace}} to 0 when creating the TimeWindows but I think that this should be the default behaviour at least when it comes to the suppress feature.
> I hope I have not misunderstood the code in my analysis, thank you :)
> Simone



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