Hi, In the same topology, I generate aggregates with 1-day windows and 1-week windows and write them in one single topic. On Mondays, these windows have the same start time. The effect: these aggregates overrides each other.
That happens because WindowedSerializer [1] only serializes the window start time. I'm a bit surprised, a window has by definition a start and an end. I suppose one wanted save on key sizes ? And/or one would consider that topics should not contain aggregates with different granularities ? I have two choices then, either create as many output topics as I have granularities, or create my own serializer which also includes the window end time. What would the community recommend ? Getting back to the core problem: I could understand that it's not "right" to store different granularities in one topic, and I thought it would save resources (less topic to manage by Kafka). But, I'm really not sure about this default serializer: it does not serialize all instance variables of the `Window` class, and more generally does comply to the definition of a window. [1] https://github.com/apache/kafka/blob/0.10.1/streams/src/main/java/org/apache/kafka/streams/kstream/internals/WindowedSerializer.java Thanks. Nicolas
