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https://issues.apache.org/jira/browse/FLINK-5658?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15941000#comment-15941000
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ASF GitHub Bot commented on FLINK-5658:
---------------------------------------

Github user sunjincheng121 commented on a diff in the pull request:

    https://github.com/apache/flink/pull/3386#discussion_r107982106
  
    --- Diff: 
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/plan/nodes/datastream/DataStreamOverAggregate.scala
 ---
    @@ -112,7 +113,12 @@ class DataStreamOverAggregate(
                   "condition.")
             }
           case _: RowTimeType =>
    -        throw new TableException("OVER Window of the EventTime type is not 
currently supported.")
    +        if (overWindow.lowerBound.isUnbounded && 
overWindow.upperBound.isCurrentRow) {
    +          createUnboundedAndCurrentRowEventTimeOverWindow(inputDS)
    --- End diff --
    
    EVENT-TIME OVER Need to treatment "rows" and "range" clause separately, 
because 
    -  ROWS specifies the window in physical units (rows).
    -  RANGE specifies the window as a logical offset.
    
    They have different semantics, for example:
    DATA:
    ```
    (long, int, String)
    (1L, 1, "H")
    (2L, 2, "H")
    (2L, 3,"H")
    ```
    ROWS sum(b) result: `1,3,6`
    RANGE sum(b) result: `1,6,6`



> Add event time OVER RANGE BETWEEN UNBOUNDED PRECEDING aggregation to SQL
> ------------------------------------------------------------------------
>
>                 Key: FLINK-5658
>                 URL: https://issues.apache.org/jira/browse/FLINK-5658
>             Project: Flink
>          Issue Type: Sub-task
>          Components: Table API & SQL
>            Reporter: Fabian Hueske
>            Assignee: Yuhong Hong
>
> The goal of this issue is to add support for OVER RANGE aggregations on event 
> time streams to the SQL interface.
> Queries similar to the following should be supported:
> {code}
> SELECT 
>   a, 
>   SUM(b) OVER (PARTITION BY c ORDER BY rowTime() RANGE BETWEEN UNBOUNDED 
> PRECEDING AND CURRENT ROW) AS sumB,
>   MIN(b) OVER (PARTITION BY c ORDER BY rowTime() RANGE BETWEEN UNBOUNDED 
> PRECEDING AND CURRENT ROW) AS minB
> FROM myStream
> {code}
> The following restrictions should initially apply:
> - All OVER clauses in the same SELECT clause must be exactly the same.
> - The PARTITION BY clause is optional (no partitioning results in single 
> threaded execution).
> - The ORDER BY clause may only have rowTime() as parameter. rowTime() is a 
> parameterless scalar function that just indicates processing time mode.
> - bounded PRECEDING is not supported (see FLINK-5655)
> - FOLLOWING is not supported.
> The restrictions will be resolved in follow up issues. If we find that some 
> of the restrictions are trivial to address, we can add the functionality in 
> this issue as well.
> This issue includes:
> - Design of the DataStream operator to compute OVER ROW aggregates
> - Translation from Calcite's RelNode representation (LogicalProject with 
> RexOver expression).



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