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Paul Snively commented on KAFKA-9517: ------------------------------------- [~vvcephei], that's great news! First, let me thank you again for your prompt attention. It's done a great deal to restore my confidence in Kafka Streams. Second, and I hate to ask because I know it's a big project with many other customers with various needs, but do you happen to have some idea when a 2.4.1 might be available with fixes for these, and is there anything I can do to help with the process? Thanks again! > KTable Joins Without Materialized Argument Yield Results That Further Joins > NPE On > ---------------------------------------------------------------------------------- > > Key: KAFKA-9517 > URL: https://issues.apache.org/jira/browse/KAFKA-9517 > Project: Kafka > Issue Type: Bug > Components: streams > Affects Versions: 2.4.0 > Reporter: Paul Snively > Priority: Critical > > The `KTable` API implemented [[here||#L842-L844]] > [https://github.com/apache/kafka/blob/2.4.0/streams/src/main/java/org/apache/kafka/streams/kstream/internals/KTableImpl.java#L842-L844] > []|#L842-L844]] calls `doJoinOnForeignKey` with an argument of > `Materialized.with(null, null)`, as apparently do several other APIs. As the > comment spanning [these lines|#L1098-L1099]] makes clear, the result is a > `KTable` whose `valueSerde` (as a `KTableImpl`) is `null`. Therefore, > attempts to `join` etc. on the resulting `KTable` fail with a > `NullPointerException`. > While there is an obvious workaround—explicitly construct the required > `Materialized` and use the APIs that take it as an argument—I have to admit I > find the existence of public APIs with this sort of bug, particularly when > the bug is literally documented as a comment in the source code, astonishing > to the point of incredulity. It calls the quality and trustworthiness of > Kafka Streams into serious question, and if a resolution is not forthcoming > within a week, we will be left with no other option but to consider technical > alternatives. -- This message was sent by Atlassian Jira (v8.3.4#803005)