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https://issues.apache.org/jira/browse/FLINK-23747?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17407752#comment-17407752
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Xintong Song commented on FLINK-23747:
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[~liliwei],
This ticket is for the new feature to be manually tested by someone who was not
part of the designing and implementation of the feature, in order to point out
the blind spots.
To be specific, we expect you to play the role of a user, reading the docs and
trying out the feature, and reporting anything you feel not right / unexpected
/ confusing.
Adding more testing codes is welcome but not necessary.
> Testing Window TVF offset
> -------------------------
>
> Key: FLINK-23747
> URL: https://issues.apache.org/jira/browse/FLINK-23747
> Project: Flink
> Issue Type: Improvement
> Components: Tests
> Reporter: JING ZHANG
> Assignee: liwei li
> Priority: Blocker
> Labels: release-testing
> Fix For: 1.14.0
>
>
> Window offset is an optional parameter which could be used to change the
> alignment of windows.
> There are something we need clarify about window offset:
> (1) In SQL, window offset is an optional parameter, if it is specified, it is
> the last parameter of the window.
> for Tumble window
> {code:java}
> TUMBLE(TABLE MyTable, DESCRIPTOR(rowtime), INTERVAL '15' MINUTE, INTERVAL '5'
> MINUTE){code}
> for Hop Window
> {code:java}
> HOP(TABLE MyTable, DESCRIPTOR(rowtime), INTERVAL '1' MINUTE, INTERVAL '15'
> MINUTE,
> INTERVAL '5' MINUTE){code}
> for Cumulate Window
> {code:java}
> CUMULATE(TABLE MyTable, DESCRIPTOR(rowtime), INTERVAL '1' MINUTE, INTERVAL
> '15' MINUTE, INTERVAL '5' MINUTE){code}
> (2) Window offset could be positive duration and negative duration.
> (3) Window offset is used to change the alignment of Windows. The same record
> may be assigned to the different window after set window offset. But it
> always apply a rule, timestamp >= window_start && timestamp < window_end.
> Give a demo, for a tumble window, window size is 10 MINUTE, which window
> would be assigned to for a record with timestamp 2021-06-30 00:00:04?
> # offset is '-16 MINUTE', the record assigns to window [2021-06-29
> 23:54:00, 2021-06-30 00:04:00)
> # offset is '-6 MINUTE', the record assigns to window [2021-06-29 23:54:00,
> 2021-06-30 00:04:00)
> # offset is '-4 MINUTE', the record assigns to window [2021-06-29 23:56:00,
> 2021-06-30 00:06:00)
> # offset is '0', the record assigns to window [2021-06-30 00:00:00,
> 2021-06-30 00:10:00)
> # offset is '4 MINUTE', the record assigns to window [2021-06-29 23:54:00,
> 2021-06-30 00:04:00)
> # offset is '6 MINUTE, the record assigns to window [2021-06-29 23:56:00,
> 2021-06-30 00:06:00)
> # offset is '16 MINUTE', the record assigns to window [2021-06-29 23:56:00,
> 2021-06-30 00:06:00)
> (4) We could find that, some window offset parameters may have same effect on
> the alignment of windows, in the above case, '-16 MINUTE' /'-6 MINUTE'/'4
> MINUTE' have same effect on a tumble window with '10 MINUTE' size.
> (5) Window offset is only used to change the alignment of Windows, it has no
> effect on watermark.
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