[KAFKA-7753] ValueTransformerWithKey should not require producing one value every message

• Type: Wish
• Status: Resolved
• Priority: Minor
• Resolution: Feedback Received
• Component/s: streams
• Assignee: Unassigned
• Reporter: Mateusz Owczarek
• Created: 18/Dec/18 17:01
• Updated: 20/Dec/18 15:45
• Resolved: 20/Dec/18 15:45

Description

Hi, speaking about: https://github.com/apache/kafka/blob/trunk/streams/src/main/java/org/apache/kafka/streams/kstream/ValueTransformerWithKey.java
I have a quite simple case - I want to implement a Transformer which I will use later in my DSL-api-defined topology. Those are my requirements:

• no repartition topic should be created since I do not change the keys
• I can't forward messages on every message transformed. I have my internal state store which I'm using to ensure max. 1 message per window is sent.

Basic transformer gives me possibility to not send messages down the stream (null internal handler), but it forces repartitioning which I think is unnecessary in my case. WDYT?