Hartmut Armbruster created KAFKA-18972:
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             Summary: Custom Processor supplied on addReadOnlyStateStore is not 
used when restoring state from topic
                 Key: KAFKA-18972
                 URL: https://issues.apache.org/jira/browse/KAFKA-18972
             Project: Kafka
          Issue Type: Bug
          Components: streams
    Affects Versions: 3.8.1, 3.9.0, 3.8.0
            Reporter: Hartmut Armbruster


As a Streams Developer, I have added a custom read-only state store 
(Topology#addReadOnlyStateStore(_)) to my Topology, using a custom Processor 
for state updates (ProcessorSupplier<KIn, VIn, Void, Void> stateUpdateSupplier).

*Expected behaviour:* As per JavaDocs, "the Processor should contain logic to 
keep the StateStore up-to-date". Therefore, it should be used for processing 
and persisting every event, both in _RUNNING_ state for new events and during 
state restoration (directly from the source topic).

*Actual behaviour:* During state restoration, events are written directly to 
the store, bypassing the Processor entirely.

Here's a related discussion on community slack: 
[https://confluentcommunity.slack.com/archives/C48AHTCUQ/p1741617964189859?thread_ts=1741539889.829939&cid=C48AHTCUQ]

There was a similar bug fixed recently for GlobalStore -> 
https://issues.apache.org/jira/browse/KAFKA-7663



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