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https://issues.apache.org/jira/browse/KAFKA-8037?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17166602#comment-17166602
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Guozhang Wang commented on KAFKA-8037:
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Per the interaction: I'm actually suggesting that the source-topic reuse would
NOT be part of the topology optimization moving forward and are ONLY be
controlled by the per-store APIs, and hence it would not be related to the
`topology.optimization` any more.
Per the serde: the current rule is, if `Consumed` is specified only, use that
for both source topic and state store, and similarly if `Materialized` is
specified only, use that for both source topic and state store; if both are
specified, `Consumed` serde will override `Materialized` serde. So today we are
guaranteed that only one serde will be used. My previous comment was not very
clear, what I meant is that for IQ we just use the only serde, whatever it is,
to deserialize the bytes (note they are just raw bytes from source topics
directly).
> KTable restore may load bad data
> --------------------------------
>
> Key: KAFKA-8037
> URL: https://issues.apache.org/jira/browse/KAFKA-8037
> Project: Kafka
> Issue Type: Improvement
> Components: streams
> Reporter: Matthias J. Sax
> Priority: Minor
> Labels: pull-request-available
>
> If an input topic contains bad data, users can specify a
> `deserialization.exception.handler` to drop corrupted records on read.
> However, this mechanism may be by-passed on restore. Assume a
> `builder.table()` call reads and drops a corrupted record. If the table state
> is lost and restored from the changelog topic, the corrupted record may be
> copied into the store, because on restore plain bytes are copied.
> If the KTable is used in a join, an internal `store.get()` call to lookup the
> record would fail with a deserialization exception if the value part cannot
> be deserialized.
> GlobalKTables are affected, too (cf. KAFKA-7663 that may allow a fix for
> GlobalKTable case). It's unclear to me atm, how this issue could be addressed
> for KTables though.
> Note, that user state stores are not affected, because they always have a
> dedicated changelog topic (and don't reuse an input topic) and thus the
> corrupted record would not be written into the changelog.
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