Victor van den Hoven created KAFKA-15417:
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Summary: JoinWindow does not seem to work properly with a KStream
- KStream - LeftJoin()
Key: KAFKA-15417
URL: https://issues.apache.org/jira/browse/KAFKA-15417
Project: Kafka
Issue Type: Bug
Components: streams
Affects Versions: 3.4.0
Reporter: Victor van den Hoven
Attachments: SimpleStreamTopology.java, SimpleStreamTopologyTest.java
In Kafka-streams 3.4.0 :
According to the javadoc of the Joinwindow:
_There are three different window configuration supported:_
* _before = after = time-difference_
* _before = 0 and after = time-difference_
* _*before = time-difference and after = 0*_
However if I use a joinWindow with *before = time-difference and after = 0*
on a kstream-kstream-leftjoin the *after=0* part does not seem to work.
When using _stream1.leftjoin(stream2, joinWindow)_ with
{_}joinWindow{_}.{_}after=0 and joinWindow.before=30s{_}, any new message on
stream 1 that can not be joined with any messages on stream2 should be joined
with a null-record after the _joinWindow.after_ has ended and a new message has
arrived on stream1.
It does not.
Only if the new message arrives after the value of _joinWindow.before_ the
previous message will be joined with a null-record.
Attached you can find two files with a TopologyTestDriver Unit test to
reproduce.
topology: stream1.leftjoin( stream2, joiner, joinwindow)
joinWindow has before=5000ms and after=0
message1(key1) -> stream1
after 4000ms message2(key2) -> stream1 -> NO null-record join was made, but
the after period was expired.
after 4900ms message2(key2) -> stream1 -> NO null-record join was made, but
the after period was expired.
after 5000ms message2(key2) -> stream1 -> A null-record join was made,
before period was expired.
after 6000ms message2(key2) -> stream1 -> A null-record join was made,
before period was expired.
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