[ https://issues.apache.org/jira/browse/KAFKA-9517?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Paul Snively updated KAFKA-9517: -------------------------------- Description: 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. was: The `KTable` API implemented [here|[https://github.com/apache/kafka/blob/2.4.0/streams/src/main/java/org/apache/kafka/streams/kstream/internals/KTableImpl.java#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. > 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)