Matthias J. Sax created KAFKA-12839:
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Summary: SlidingWindow with size 0 fails
Key: KAFKA-12839
URL: https://issues.apache.org/jira/browse/KAFKA-12839
Project: Kafka
Issue Type: Bug
Components: streams
Reporter: Matthias J. Sax
Trying to use a sliding window with time-difference 0 (that is officially
supported) fails with an exception and Kafka Stream crashes with
{{IllegalArgumentException: Window endMs must be greater than window startMs}}
The underlying issue is the usage of {{TimeWindow}} to represent the window
what is incorrect.
{{TimeWindow}} is designed for hopping/tumbling windows with an inclusive lower
and exclusive upper bound. Thus, the upper bound must be larger than the lower
bound, because otherwise the window would have a negative size what is not
allowed.
For sliding windows, we use include lower and upper bound though, and thus want
to set upper and lower bound to be the same, what would still result in a
window of size 1 (note that time-difference of 0 results in window size 1).
It seems we need to introduce a new {{SlidingWindow}} type.
Note, that for a non-zero time-difference, the window bounds are computed
"correctly", however, {{TimeWindow}} is still an incorrect representation
because it represents `[start,end)` instead of `[start,end]`.
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