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From "sunjincheng (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-5658) Add event time OVER RANGE BETWEEN UNBOUNDED PRECEDING aggregation to SQL
Date Tue, 07 Feb 2017 14:34:43 GMT

    [ https://issues.apache.org/jira/browse/FLINK-5658?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15856095#comment-15856095
] 

sunjincheng commented on FLINK-5658:
------------------------------------

Hi,[~Yuhong_kyo] I'm glad you're interested in this jira, and I'm trying to explain your question:

 1. The semantics of OVER determines that both "processing-time" and "event-time" are output
one result  per row.
 2. For your example, IMO:
* Without retraction situation, the output of the results are:
{code}
    A-> agg (A)
    B-> agg (A, B)
    C-> agg (A, B, C)
    D-> agg (A, B, D)
{code}
* With retraction situation:
{code}
    A-> agg (A)
    B-> agg (A, B)
    C-> agg (A, B, C)
    D-> agg (A, B, D)
    C-> retraction agg (A, B, C)
    C-> agg (A, B, D,C)
{code}
These are my thoughts, for reference purposes only! 
What do you think ? [~Yuhong_kyo] [~fhueske]  If there is any mistake please let me know.
 

> 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: sunjincheng
>
> 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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