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https://issues.apache.org/jira/browse/FLINK-5624?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15856362#comment-15856362
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Fabian Hueske commented on FLINK-5624:
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Copying a comment from FLINK-5710.
The idea is to kind of apply pattern matching for certain expressions such as
{{GROUP BY FLOOR(procTime() TO HOURS)}}.
The challenge is that this expression is spread across several LogicalRel nodes.
The expression {{FLOOR(procTime() TO HOURS)}} will be moved into a
{{LogicalProject}} (or {{LogicalCalc}}) to create a new attribute. A following
{{LogicalAggregate}} will then use that attribute as a grouping column.
Once we detect such a pattern, we have to rewrite the plan and replace the
{{LogicalAggregate}} and parts of the {{LogicalProject}} by a
{{LogicalWindowAggregate}}. The {{LogicalWindowAggregate}} includes a window
definition. Depending on which marker function is used ({{rowtime}} or
{{proctime}}) the window definition is either for a processing or an event time
window. After the translation, the function is no longer available.
With this approach, we can only translate very specific queries. However, I
don't think we can easily provide a generic translation for SQL window queries.
With Calcite's special window functions TUMBLE, HOP, and SESSION (see
Calcite-1345 and http://calcite.apache.org/docs/stream.html) the detection of
windowing patterns will be much easier.
> Support tumbling window on streaming tables in the SQL API
> ----------------------------------------------------------
>
> Key: FLINK-5624
> URL: https://issues.apache.org/jira/browse/FLINK-5624
> Project: Flink
> Issue Type: Bug
> Components: Table API & SQL
> Reporter: Haohui Mai
> Assignee: Haohui Mai
>
> This is a follow up of FLINK-4691.
> FLINK-4691 adds supports for group-windows for streaming tables. This jira
> proposes to expose the functionality in the SQL layer via the {{GROUP BY}}
> clauses, as described in
> http://calcite.apache.org/docs/stream.html#tumbling-windows.
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