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https://issues.apache.org/jira/browse/KAFKA-4887?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15930727#comment-15930727
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Guozhang Wang commented on KAFKA-4887:
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Got it. Thanks.
As for the fix, we should probably consider not using caching at all if dedup
is disabled since that is the whole purpose of having a cache at the first
place. Thoughts [~damianguy] [~enothereska] [~mjsax]?
> Enabling caching on a persistent window store breaks support for duplicate
> insertion
> ------------------------------------------------------------------------------------
>
> Key: KAFKA-4887
> URL: https://issues.apache.org/jira/browse/KAFKA-4887
> Project: Kafka
> Issue Type: Bug
> Components: streams
> Affects Versions: 0.10.2.0
> Reporter: Elias Levy
>
> {{CachingWindowStore}} and {{RocksDBWindowStore}} interact badly when
> duplicate insertion support is enabled by passing {{true}} as the fourth
> argument to {{windowed}} in the state store supplier.
> When the feature is enabled, {{RocksDBWindowStore}} correct handles
> duplicates by assigning a unique sequence number to each element on insertion
> and using the number within the key.
> When caching is enabled by calling {{enableCaching}} on the supplier,
> {{CachingWindowStore}} fails to the the same. Thus, of multiple values
> inserted with the same key, only the last one survives.
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