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https://issues.apache.org/jira/browse/KAFKA-9517?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17033785#comment-17033785
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Paul Snively commented on KAFKA-9517:
-------------------------------------
Thanks for the suggestion to squash and cherry-pick #8015 and #8061. I've done
that, and `.gradlew test` is giving me four errors that seem related to the
cherry-picked PRs. I'm attaching the test report for others to perhaps analyze.
My colleague and I will also attempt to reproduce the issues we specifically
encountered in using 2.4.0. I'm reasonably confident we can also take some time
to review these two PRs, but that seems somewhat unlikely to happen today.
[^test.tar.xz]
> 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
> Assignee: John Roesler
> Priority: Blocker
> Fix For: 2.5.0, 2.4.1
>
> Attachments: test.tar.xz
>
>
> 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.
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