[jira] [Created] (FLINK-21977) Allow bigger offset in SlidingProcessingTimeWindows

[Shang Yuanchun (Jira)]

Moritz Manner created FLINK-21977:
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             Summary: Allow bigger offset in SlidingProcessingTimeWindows
                 Key: FLINK-21977
                 URL: https://issues.apache.org/jira/browse/FLINK-21977
             Project: Flink
          Issue Type: Bug
          Components: API / DataStream
    Affects Versions: 1.12.2
            Reporter: Moritz Manner


According to the docs about [Windows|https://ci.apache.org/projects/flink/flink-docs-stable/dev/stream/operators/windows.html#sliding-windows], the _SlidingProcessingTimeWindows_ supports an _offset_ with an absolute value bigger than the _slide_ of the window:

 
{code:java}
// sliding processing-time windows offset by -8 hours
input
    .keyBy(<key selector>)
    .window(SlidingProcessingTimeWindows.of(Time.hours(12), Time.hours(1), Time.hours(-8)))
    .<windowed transformation>(<window function>);{code}
 

This is currently not possible, as an _IllegalArgumentException_ will be thrown if the absolute value of the _offset_ is bigger than the _slide_.
{code:java}
private SlidingProcessingTimeWindows(long size, long slide, long offset) {
    if (Math.abs(offset) >= slide || size <= 0) {
        throw new IllegalArgumentException(
                "SlidingProcessingTimeWindows parameters must satisfy "
                        + "abs(offset) < slide and size > 0");
    }

    this.size = size;
    this.slide = slide;
    this.offset = offset;
}{code}
I suspect the absolute value of the _offset_ should be compared to the *_size_* of the window - similar to the _TumblingProcessingTimeWindows._

This problem exists also in the _Sliding*Event*TimeWindows._

 



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