[jira] [Created] (KAFKA-8037) KTable restore may load bad data

["Matthias J. Sax (JIRA)" <ji...@apache.org>]

Matthias J. Sax created KAFKA-8037:
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             Summary: 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


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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