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Posted to jira@kafka.apache.org by "Paul Snively (Jira)" <ji...@apache.org> on 2020/02/06 19:58:00 UTC
[jira] [Updated] (KAFKA-9517) KTable Joins Without Materialized
Argument Yield Results That Further Joins NPE On
[ 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|[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.
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|[https://github.com/apache/kafka/blob/2.4.0/streams/src/main/java/org/apache/kafka/streams/kstream/internals/KTableImpl.java#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|[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.
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