[ https://issues.apache.org/jira/browse/KAFKA-6599?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Guozhang Wang updated KAFKA-6599: --------------------------------- Labels: bug (was: ) > KTable KTable join semantics violated when caching enabled > ---------------------------------------------------------- > > Key: KAFKA-6599 > URL: https://issues.apache.org/jira/browse/KAFKA-6599 > Project: Kafka > Issue Type: Bug > Components: streams > Reporter: Jan Filipiak > Priority: Critical > Labels: bug > > Say a tuple A,B got emmited after joining and the delete for A goes into the > cache. After that the B record would be deleted aswell. B's join processor > would look up A and see `null` while computing for old and new value (at this > point we can execute joiner with A beeing null and still emit something, but > its not gonna represent the actual oldValue) Then As cache flushes it doesn't > see B so its also not gonna put a proper oldValue. The output can then not be > used for say any aggregate as a delete would not reliably find its old > aggregate where it needs to be removed from filter will also break as it > stopps null,null changes from propagating. So for me it looks pretty clearly > that Caching with Join breaks KTable semantics. be it my new join or the > currently existing once. > > this if branch here > [https://github.com/apache/kafka/blob/1.0/streams/src/main/java/org/apache/kafka/streams/state/internals/CachingKeyValueStore.java#L155] > is not usefull. I think its there because when one would delegate the true > case to the underlying. One would get proper semantics for streams, but the > weiredest cache I've seen. > -- This message was sent by Atlassian JIRA (v7.6.3#76005)