[KAFKA-7577] Semantics of Table-Table Join with Null Message Are Incorrect

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Not A Problem
• Affects Version/s: 1.1.0
• Component/s: streams
• Assignee: Unassigned
• Reporter: Daren Thomas
• Created: 31/Oct/18 21:03
• Updated: 20/Nov/18 20:52
• Resolved: 20/Nov/18 20:47

Description

Observed behavior of Table-Table join with a Null Message does not match the semantics described in the documentation (https://docs.confluent.io/current/streams/developer-guide/dsl-api.html#ktable-ktable-join).  The expectation is:

• Message A results in [A, null] from the Left Join
• Message null (tombstone) results in null (tombstone) from the Left Join

 The observed behavior was that the null (tombstone) message did not pass through the Left Join to the output topic like expected.  This behavior was observed with and without caching enabled, against a test harness, and against a local Confluent 5.0.0 platform.  It was also observed that the KTableKTableLeftJoinProcessor.process() function was not called for the null (tombstone) message.

Issue Links

• is related to: KAFKA-6036 Enable logical materialization to physical materialization
• is related to: KAFKA-7658 Add KStream#toTable to the Streams DSL