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Matthias J. Sax commented on KAFKA-7653: ---------------------------------------- If an implicit can be written in a way such that it returns a new object each time, it might be fair to document this and make it a requirement. For the second part: the compiler does not need to distinguish both cases IMHO. At runtime, we get two Serde-objects, one for the key, and one for the value, and we can call `configure()` correctly for each. Or do I miss something? > Streams-Scala: Add type level differentiation for Key and Value serdes. > ----------------------------------------------------------------------- > > Key: KAFKA-7653 > URL: https://issues.apache.org/jira/browse/KAFKA-7653 > Project: Kafka > Issue Type: Improvement > Components: streams > Reporter: Mark Tranter > Assignee: Mark Tranter > Priority: Minor > Labels: scala > > Implicit resolution/conversion of Serdes/Consumed etc is a big improvement > for the Scala Streams API. However in cases where a user needs to > differentiate between Key and Value serializer functionality (i.e. using the > Schema Registry), implicit resolution doesn't help and could cause issues. > e.g. > {code:java} > case class MouseClickEvent(pageId: Long, userId: String) > builder > // Long serde taken from implicit scope configured with > // `isKey` = true > .stream[Long, MouseClickEvent]("mouse-clicks") > .selectKey((_,v) => v.userId) > .groupByKey > .aggregate(() => 0L, (_: String, mce: MouseClickEvent, count: Long) => > count + 1) > .toStream > // Same Long serde taken from implicit scope configured with > // `isKey` = true, even thought the `Long` value in this case > // will be the Value > .to("mouse-clicks-by-user") > {code} > It would be ideal if Key and Value Serde/SerdeWrapper types/type classes > could be introduced to overcome this limitation. -- This message was sent by Atlassian JIRA (v7.6.3#76005)