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Bruno Cadonna commented on KAFKA-4217: -------------------------------------- Is this issue still relevant? The docs of [{{transform}}|https://kafka.apache.org/11/javadoc/org/apache/kafka/streams/kstream/KStream.html#transform-org.apache.kafka.streams.kstream.TransformerSupplier-java.lang.String...-] say "Transform each record of the input stream into zero or more records in the output stream", which sounds to me as if this issue has been already resolved. > KStream.transform equivalent of flatMap > --------------------------------------- > > Key: KAFKA-4217 > URL: https://issues.apache.org/jira/browse/KAFKA-4217 > Project: Kafka > Issue Type: Improvement > Components: streams > Affects Versions: 0.10.0.1 > Reporter: Elias Levy > Priority: Major > Labels: api, needs-kip, newbie > > {{KStream.transform}} gives you access to state stores while allowing you to > return zero or one transformed {{KeyValue}}. Alas, it is unclear what method > you should use if you want to access state stores and return zero or multiple > {{KeyValue}}. Presumably you can use {{transform}}, always return {{null}}, > and use {{ProcessorContext.forward}} to emit {{KeyValues}}. > It may be good to introduce a {{transform}}-like {{flatMap}} equivalent, or > allow store access from other {{KStream}} methods, such as {{flatMap}} itself. -- This message was sent by Atlassian JIRA (v7.6.3#76005)