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https://issues.apache.org/jira/browse/KAFKA-9259?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17245308#comment-17245308
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highluck commented on KAFKA-9259:
---------------------------------
[~omanges]
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> suppress() for windowed-Serdes does not work with default serdes
> ----------------------------------------------------------------
>
> Key: KAFKA-9259
> URL: https://issues.apache.org/jira/browse/KAFKA-9259
> Project: Kafka
> Issue Type: Bug
> Components: streams
> Affects Versions: 2.1.0
> Reporter: Matthias J. Sax
> Assignee: Omkar Mestry
> Priority: Major
> Labels: newbie
>
> The suppress() operator either inherits serdes from its upstream operator or
> falls back to default serdes from the config.
> If the upstream operator is an windowed aggregation, the window-aggregation
> operator wraps the user passed-in serde with a window-serde and pushed it
> into suppress() – however, if default serdes are used, the window-aggregation
> operator cannot push anything into suppress(). At runtime, it just creates a
> default serde and wraps it according. For this case, suppress() also falls
> back to default serdes; however, it does not wrap the serde and thus a
> ClassCastException is thrown when the serde is used later.
> suppress() is already aware if the upstream aggregation is time/session
> windowed or not and thus should use this information to wrap default serdes
> accordingly.
> The current workaround for windowed-suppress is to overwrite the default
> serde upstream to suppress(), such that suppress() inherits serdes and does
> not fall back to default serdes.
>
> For the search engines, when using Avro, this results in a ClassCastException:
> {{Caused by: java.lang.ClassCastException: class
> org.apache.kafka.streams.kstream.Windowed cannot be cast to class
> org.apache.avro.specific.SpecificRecord
> (org.apache.kafka.streams.kstream.Windowed and
> org.apache.avro.specific.SpecificRecord are in unnamed module of loader
> 'app') at
> io.confluent.kafka.streams.serdes.avro.SpecificAvroSerializer.serialize(SpecificAvroSerializer.java:38)}}
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