[
https://issues.apache.org/jira/browse/KAFKA-12815?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17347995#comment-17347995
]
Guozhang Wang commented on KAFKA-12815:
---------------------------------------
For the longer term, I feel that we either need to 1) persist the topic /
offset information into the upstream materialized store as well, or 2) just
disable this optimization for KTable.transformValues(), or at least allow users
to opt-in / opt-out if they know the risks of calling context.topic() /
offset(). Personally, I'd lean towards 2). [~mjsax] maybe we should create a
new ticket open for this longer term solution?
> KTable.transformValue might have incorrect record metadata
> ----------------------------------------------------------
>
> Key: KAFKA-12815
> URL: https://issues.apache.org/jira/browse/KAFKA-12815
> Project: Kafka
> Issue Type: Bug
> Components: streams
> Reporter: Matthias J. Sax
> Assignee: Matthias J. Sax
> Priority: Major
> Fix For: 3.0.0
>
>
> In the DSL, Kafka Streams applies an optimization for non-materialized
> tables: when these are queried an upstream state store is accessed. To ensure
> that the correct value is returned from the lookup, all intermediate
> processors after the materialized store, and before the processor that
> triggers the lookup are re-applied (cf `KTableValueGetter`).
> For re-applying DSL operators like filter/mapValues that works fine. However,
> for transformValue(), the method is executed with the incorrect
> `RecordContext` (note that DSL operators like filter don't have access to the
> `RecordContext` and thus, are not subject to this bug). Instead of using the
> record context from the value that was received from the upstream state store
> (and that is re-processed), the transformer would see the context from the
> record that triggered the lookup.
> Thus, the information about timestamp, offset, partition, topic name, and
> headers is incorrect.
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
