THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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How to compute an (windowed) average?
Kafka Streams DSL aggregation natively support so-called "incremental" or "cumulative" aggregation functions (cf, https://en.wikipedia.org/wiki/Associative_property – also called "distributive functions" by Jim Gray in "Data Cube: A Relational Aggregation Operator Generalizing Group-By, Cross-Tab, and Sub-Totals") like count, sum, min, max. However, average function (a so-called "algebraic" function, cf. "Data Cube: A Relational Aggregation Operator Generalizing Group-By, Cross-Tab, and Sub-Totals") cannot be computed like this, but it can be composed of distributive functions, namely count and sum. Thus, it can be implemented in a two step approach:
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