Ayoub Omari created KAFKA-16394: ----------------------------------- Summary: ForeignKey LEFT join propagates null value on foreignKey change Key: KAFKA-16394 URL: https://issues.apache.org/jira/browse/KAFKA-16394 Project: Kafka Issue Type: Bug Components: streams Affects Versions: 3.7.0 Reporter: Ayoub Omari Attachments: ForeignJoinTest.scala, JsonSerde.scala
We have two topics : _left-topic[String, LeftRecord]_ and _right-topic[String, String]_ where _LeftRecord_ : {code:scala} case class LeftRecord(foreignKey: String, name: String){code} we do a simple foreign key join on left-topic's foreignKey field which returns the value in right-topic. +*Scenario1: change foreignKey*+ Input the following {code:scala} rightTopic.pipeInput("fk1", "1") rightTopic.pipeInput("fk2", "2") leftTopic.pipeInput("pk1", LeftRecord("fk1", "pk1")) leftTopic.pipeInput("pk1", LeftRecord("fk2", "pk1")) {code} *+Expected result+* {code:scala} KeyValue(pk1, 1) KeyValue(pk1, 2){code} *+Actual result+* {code:scala} KeyValue(pk1, 1) KeyValue(pk1, null) KeyValue(pk1, 2){code} A null is propagated to the join result when the foreign key changes +*Scenario 2: Delete PrimaryKey*+ Input {code:scala} rightTopic.pipeInput("fk1", "1") rightTopic.pipeInput("fk2", "2") leftTopic.pipeInput("pk1", LeftRecord("fk1", "pk1")) leftTopic.pipeInput("pk1", null) {code} *+Expected result+* {code:scala} KeyValue(pk1, 1) KeyValue(pk1, null) {code} *+Actual result+* {code:java} KeyValue(pk1, 1) KeyValue(pk1, null) KeyValue(pk1, null) {code} An additional null is propagated to the join result. This bug doesn't exist on versions 3.6.0 and below. I believe the issue comes from the line [https://github.com/apache/kafka/blob/trunk/streams/src/main/java/org/apache/kafka/streams/kstream/internals/foreignkeyjoin/SubscriptionSendProcessorSupplier.java#L134] where we propagate the deletion in the two scenarios above Attaching the topology I used. -- This message was sent by Atlassian Jira (v8.20.10#820010)