Add time window and window assigner

[dai-chen]

Signed-off-by: Chen Dai [email protected]

Description

Add window and window assigner interface along with tumbling and sliding window assigner implementation. This PR is only focus on core WindowAssigner interface. The future tasks in #954 will integrate it and other new windowing components with query plan operator.

Window

A Window is a time interval which has start timestamp and end timestamp. For convenience, the end timestamp is exclusive and thus the window boundary is actually [startTime, endTime-1].

Window Assigner

A WindowAssigner identifies which window(s) the event belong. This is the first step and foundation of handling unbounded streaming data. As follows, an event may be assigned to a single window or multiple windows according to the windowing function. Here are a few example for common windowing approach.

Tumble window is fixed size without any overlap and start timestamp is aligned by mod window size.

Sliding window is fixed size but overlapped by slide size. The algorithm is referencing https://github.com/apache/flink/blob/master/flink-streaming-java/src/main/java/org/apache/flink/streaming/api/windowing/assigners/SlidingEventTimeWindows.java#L70

Session windowing dynamic sized and defined by a given gap duration. It is useful for event representing user activity by analyzing user behavior within a session. Note that session window may cause window merging which will be supported in future as needed.

Issues Resolved

#951

Check List

• New functionality includes testing.
  • All tests pass, including unit test, integration test and doctest
• New functionality has been documented.
  • New functionality has javadoc added
  • New functionality has user manual doc added
• Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
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[codecov-commenter]

Codecov Report

Merging #950 (81ba090) into feature/maximus-m1 (3a9d217) will decrease coverage by 2.73%.
The diff coverage is 100.00%.

@@                   Coverage Diff                    @@
##             feature/maximus-m1     #950      +/-   ##
========================================================
- Coverage                 97.95%   95.22%   -2.74%     
- Complexity                 3143     3153      +10     
========================================================
  Files                       300      313      +13     
  Lines                      7784     8463     +679     
  Branches                    500      623     +123     
========================================================
+ Hits                       7625     8059     +434     
- Misses                      158      350     +192     
- Partials                      1       54      +53     

Flag	Coverage Δ
query-workbench	62.76% <ø> (?)
sql-engine	97.96% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...search/sql/planner/streaming/windowing/Window.java	100.00% <100.00%> (ø)
...ming/windowing/assigner/SlidingWindowAssigner.java	100.00% <100.00%> (ø)
...ing/windowing/assigner/TumblingWindowAssigner.java	100.00% <100.00%> (ø)
workbench/public/components/Header/Header.tsx	100.00% <0.00%> (ø)
...ch/public/components/QueryResults/QueryResults.tsx	61.60% <0.00%> (ø)
workbench/public/components/PPLPage/PPLPage.tsx	56.52% <0.00%> (ø)
workbench/public/components/app.tsx	0.00% <0.00%> (ø)
workbench/public/components/Main/main.tsx	53.00% <0.00%> (ø)
workbench/public/utils/PanelWrapper.tsx	100.00% <0.00%> (ø)
workbench/public/components/SQLPage/SQLPage.tsx	100.00% <0.00%> (ø)
... and 3 more

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