Matthias J. Sax created KAFKA-6400:
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             Summary: Consider setting default cache size to zero in Kafka 
Streams
                 Key: KAFKA-6400
                 URL: https://issues.apache.org/jira/browse/KAFKA-6400
             Project: Kafka
          Issue Type: Improvement
          Components: streams
    Affects Versions: 1.0.0
            Reporter: Matthias J. Sax
            Priority: Minor


Since the introduction of record caching in Kafka Streams DSL, we see regular 
reports/questions of first times users about "Kafka Streams does not emit 
anything" or "Kafka Streams loses messages". Those report are subject to record 
caching but no bugs and indicate bad user experience.

We might consider setting the default cache size to zero to avoid those issues 
and improve the experience for first time users. This hold especially for 
simple word-count-demos (Note, many people don't copy out example word-count 
but build their own first demo app.)

Remark: before we had caching, many users got confused about our update 
semantics and that we emit an output record for each input record for windowed 
aggregation (ie, please give me the "final" result"). Thus, we need to consider 
this and judge with care to not go "forth and back" with default user 
experience -- we did have less questions about this behavior lately.



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