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https://issues.apache.org/jira/browse/KAFKA-8755?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16910000#comment-16910000
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Bruno Cadonna commented on KAFKA-8755:
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{quote}So it seems that even if we get the checkpoint offset fixed in the
restore consumer that we're going to have to do a lot of catch up on failover
that we would not have had to do in the non optimized case. Is this expected
behavior?{quote}
The catchup on failover in the optimized and not optimized case should be the
same, because the data read until the last written offset from the input topic
in the optimized case should be equal to the data we've added to the store.
That is basically what the above topology does. It reads from the input topic,
writes to the store, commits (i.e., writes) the offset of the input topic. Then
it repeats those actions.
> 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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