[jira] [Assigned] (KAFKA-8755) Stand-by Task of an Optimized Source Table Does Not Write Anything to its State Store

["Chris Pettitt (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/KAFKA-8755?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Chris Pettitt reassigned KAFKA-8755:
------------------------------------

    Assignee: Chris Pettitt

> Stand-by Task of an Optimized Source Table Does Not Write Anything to its State Store
> -------------------------------------------------------------------------------------
>
>                 Key: KAFKA-8755
>                 URL: https://issues.apache.org/jira/browse/KAFKA-8755
>             Project: Kafka
>          Issue Type: Bug
>          Components: streams
>    Affects Versions: 2.4.0
>            Reporter: Bruno Cadonna
>            Assignee: Chris Pettitt
>            Priority: Major
>              Labels: newbie
>         Attachments: StandbyTaskTest.java
>
>
> With the following topology:
> {code:java}
> builder.table(
>     INPUT_TOPIC, 
>     Consumed.with(Serdes.Integer(), Serdes.Integer()), 
>     Materialized.<Integer, Integer, KeyValueStore<Bytes, byte[]>>as(stateName)
> )
> {code}
> and with topology optimization turned on, Kafka Streams uses the input topic {{INPUT_TOPIC}} as the change log topic for state store {{stateName}}. A stand-by task for such a topology should read from {{INPUT_TOPIC}} and should write the records to its state store so that the streams client that runs the stand-by task can take over the execution of the topology in case of a failure with an up-to-date replica of the state.
> Currently, the stand-by task described above reads from the input topic but does not write the records to its state store. Thus, after a failure the stand-by task cannot provide any up-to-date state store and the streams client needs to construct the state from scratch before it can take over the execution.
> The described behaviour can be reproduced with the attached test.



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