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https://issues.apache.org/jira/browse/KAFKA-12695?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17326191#comment-17326191
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Matthias J. Sax commented on KAFKA-12695:
-----------------------------------------
Thanks for reporting this. Seems that there is a gap in picking up implicits
correctly.
However, your program seems not to be too useful atm anyway – note that
`toTable` by default only changes the _interpretation of the data, but it won't
really so any processing (and it also won't create a state store by default). A
materialization might be done it the result `KTable` is used downstream, eg, in
a join or aggregation.
If you don't want to further process the result `KTable` but only want to write
the data into a state store, you will need to pass in `Materialized` parameter,
that would also allow you to specify `Serdes` (in case the bug also affects
this case and implicits are not picked up correctly).
> KStream.toTable must be extended to allow for a specific Serde
> ----------------------------------------------------------------
>
> Key: KAFKA-12695
> URL: https://issues.apache.org/jira/browse/KAFKA-12695
> Project: Kafka
> Issue Type: Bug
> Components: streams
> Affects Versions: 2.7.0
> Reporter: Yura Nosenko
> Priority: Minor
> Labels: scala
>
> KStream.toTable seems to not be as useful as it can.`KStream.toTable` seems
> to not be as useful as it can.I have a simple piece of code:
> {{ builder.stream[String, String](post)}}{{.map(postExtractor)}}{{.toTable }}
>
> {{That fails with:}}
> {{ Caused by: java.lang.ClassCastException: class java.lang.Long cannot
> be cast to class [B (java.lang.Long and [B are in module java.base of loader
> 'bootstrap')}}
> But if I tweak it to:
>
> {{builder.stream[String, String](post).map(postExtractor).to("output-topic")}}
>
> It seems that toTable can only work with the default Serde configs. But if
> it's the case it's of a limited use.
> Especially in Scala code where all Produced/Consumed can be inferred as
> implicit otherwise.
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