[jira] [Commented] (FLINK-5655) Add event time OVER RANGE BETWEEN x PRECEDING aggregation to SQL

["Haohui Mai (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-5655?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15867369#comment-15867369 ] 

Haohui Mai commented on FLINK-5655:
-----------------------------------

I'm particularly interested in the part that compiles the sliding windows from Calcite down to the DataStream operators.

Maybe a dumb question -- I wonder, is it possible to specify sliding grouped windows introduced in FLINK-4691 in this syntax? Essentially I am looking at something that directly maps to the sliding windows in the {{DataStream}} / {{Table}} APIs.

Essentially I'm looking for https://ci.apache.org/projects/flink/flink-docs-release-1.2/dev/windows.html#sliding-windows. I can see there are two possible ways to express the sliding windows:

{noformat}
1. SELECT SUM(b) OVER(PARTITION BY SlidingWindowGap(...) RANGE BETWEEN INTERVAL '1' HOUR PRECEDING AND CURRENT ROW)) FROM table
2. SELECT SUM(b) FROM table GROUP BY SlidingWindow(size, interval)
{noformat}

The approach (2) is implemented by https://msdn.microsoft.com/en-us/library/azure/dn835051.aspx. 

My question is that are (1) and (2) semantically equivalent? What is the right way to express grouped sliding windows?


> Add event time OVER RANGE BETWEEN x PRECEDING aggregation to SQL
> ----------------------------------------------------------------
>
>                 Key: FLINK-5655
>                 URL: https://issues.apache.org/jira/browse/FLINK-5655
>             Project: Flink
>          Issue Type: Sub-task
>          Components: Table API & SQL
>            Reporter: Fabian Hueske
>            Assignee: Shaoxuan Wang
>
> 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 INTERVAL '1' HOUR PRECEDING AND CURRENT ROW) AS sumB,
>   MIN(b) OVER (PARTITION BY c ORDER BY rowTime() RANGE BETWEEN INTERVAL '1' HOUR 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.
> - UNBOUNDED PRECEDING is not supported (see FLINK-5658)
> - 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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