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https://issues.apache.org/jira/browse/FLINK-23749?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17404852#comment-17404852
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Xintong Song commented on FLINK-23749:
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Thanks you [~q977734161], you are assigned.
Please let us know if you need any help.
> Testing Window Join
> -------------------
>
> Key: FLINK-23749
> URL: https://issues.apache.org/jira/browse/FLINK-23749
> Project: Flink
> Issue Type: Improvement
> Components: Tests
> Reporter: JING ZHANG
> Assignee: lixiaobao
> Priority: Blocker
> Labels: release-testing
> Fix For: 1.14.0
>
>
> The window join requires the join on condition contains window starts
> equality of input tables and window ends equality of input tables. The
> semantic of window join is the same to the [DataStream window
> join|https://ci.apache.org/projects/flink/flink-docs-master/dev/stream/operators/joining.html#window-join].
> {code:java}
> SELECT ...
> FROM L [LEFT|RIGHT|FULL OUTER] JOIN R -- L and R are relations applied
> windowing TVF
> ON L.window_start = R.window_start AND L.window_end = R.window_end AND ...
> {code}
> In the future, we can also simplify the join on clause to only include the
> window start equality if the windowing TVF is {{TUMBLE}} or {{HOP}} .
> Currently, the windowing TVFs must be the same of left and right inputs. This
> can be extended in the future, for example, tumbling windows join sliding
> windows with the same window size.
> Currently, Flink not only supports Window Join which follows after [Window
> Aggregation|https://ci.apache.org/projects/flink/flink-docs-master/docs/dev/table/sql/queries/window-agg/].
> But also supports Window Join which follows after [Windowing
> TVF|https://ci.apache.org/projects/flink/flink-docs-master/docs/dev/table/sql/queries/window-tvf/]
> .
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