[jira] [Assigned] (FLINK-18865) Missing documentation of FlinkKafkaConsumer.setStartFromEarliest behavior when a partition offset becomes out of range

["Robert Metzger (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-18865?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Robert Metzger reassigned FLINK-18865:
--------------------------------------

    Assignee: Vladimirs Kotovs

> Missing documentation of FlinkKafkaConsumer.setStartFromEarliest behavior when a partition offset becomes out of range
> ----------------------------------------------------------------------------------------------------------------------
>
>                 Key: FLINK-18865
>                 URL: https://issues.apache.org/jira/browse/FLINK-18865
>             Project: Flink
>          Issue Type: Improvement
>          Components: Documentation
>    Affects Versions: 1.12.0
>            Reporter: Vladimirs Kotovs
>            Assignee: Vladimirs Kotovs
>            Priority: Trivial
>              Labels: pull-request-available
>
> Flink documentation is missing a clear explanation of the Kafka consumer behavior configured with "setStartFromEarliest()" when a partition offset becomes out of range.
> We see the following log messages when running Flink application with Kafka topics with a configured retention period and Kafka consumer configured with "setStartFromEarliest()".
> {code:java}
> org.apache.kafka.clients.consumer.internals.Fetcher.parseCompletedFetch(Fetcher.java:999)
> org.apache.kafka.clients.consumer.internals.Fetcher 
> [Consumer clientId=consumer-3, groupId=some-consumer] Fetch offset 12956961 is out of range for partition some_topic-80, resetting offset ...]{code}
> Affected partition offset is being reset according to "auto.offset.reset" setting in the properties with "latest" as a default value that may contradict expectations when using "setStartFromEarliest()" configuration method and to cause an unexpected loss of data. 
> Flink documentation should provide a clear explanation for this behavior.
>  



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