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https://issues.apache.org/jira/browse/KAFKA-14400?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17642353#comment-17642353
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Matthias J. Sax commented on KAFKA-14400:
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{quote}Am I correct that when one +LAST+ input record is written to the
left-input stream not within any window and when no more input records are
written to any of the input streams, then this LAST input record will never be
emitted?
{quote}
That correct. In general, this is not an issue though, as in a stream
processing world, there is no such thing as a "last input record". It can be
annoying when writing tests, but for this case, you can always add a "dummy"
record as very last record to flush out all records you actually want to test.
{quote}In the kstream-kstream-join table of the "Improved Left/Outer
Stream-Stream Join" on the wiki page that was referred to: Why is "d,ts=14"
not also joined with "A,ts=3" as the window size is 15? And why is "D,ts=15"
not also joined with "A,ts=3"?
{quote}
Seems to be a c&p error – good catch! I fixed it.
> KStream - KStream - LeftJoin() does not call ValueJoiner with null value
> -------------------------------------------------------------------------
>
> Key: KAFKA-14400
> URL: https://issues.apache.org/jira/browse/KAFKA-14400
> Project: Kafka
> Issue Type: Bug
> Components: streams
> Affects Versions: 3.1.1, 3.3.1
> Environment: Windows PC
> Reporter: Victor van den Hoven
> Priority: Major
> Attachments: Afbeelding 2.png, SimpleStreamTopology.java,
> SimpleStreamTopologyTest.java
>
>
> In Kafka-streams 3.1.1 :
> When using +JoinWindows.ofTimeDifferenceWithNoGrace(Duration.ofMillis(10000))+
> the KStream {*}leftJoin{*}(KStream otherStream, ValueJoiner {_}joiner{_},
> JoinWindows windows) does not seem to call the _joiner_ with null value when
> join predicate is not satisfied (not expected).
>
> When using deprecated +JoinWindows.of(Duration.ofMillis(10000));+
> the KStream {*}leftJoin{*}(KStream otherStream, ValueJoiner {_}joiner{_},
> JoinWindows windows) does
> call the _joiner_ with null value when join predicate is not satisfied (as
> expected and documented).
>
> Attached you can find two files with TopologyTestDriver Unit test to
> reproduce.
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