[jira] [Assigned] (FLINK-40483) Support batch Top-N optimization for ROW_NUMBER()

["Dian Fu (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-40483?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Dian Fu reassigned FLINK-40483:
-------------------------------

    Assignee: Timo Theusner

> Support batch Top-N optimization for ROW_NUMBER()
> -------------------------------------------------
>
>                 Key: FLINK-40483
>                 URL: https://issues.apache.org/jira/browse/FLINK-40483
>             Project: Flink
>          Issue Type: Improvement
>          Components: Table SQL / Planner
>            Reporter: Timo Theusner
>            Assignee: Timo Theusner
>            Priority: Major
>
> The batch planner does not optimize {{ROW_NUMBER() OVER (PARTITION BY … ORDER BY …) … WHERE rn <= N}} into a Top-N Rank operator. It falls back to a full {{OverAggregate}} that computes the row number for every row, followed by a Calc filter. The streaming planner does perform this optimization (Rank/Deduplicate).
> Example query:
> {code:SQL}
> SELECT a, b, c FROM (
>   SELECT a, b, c, ROW_NUMBER() OVER (PARTITION BY b ORDER BY c DESC) AS rn
>   FROM MyTable) t
> WHERE rn = 1
> {code}
> Batch plan:
> {code:SQL}
> Calc(where=[w0$o0 = 1])
> +- OverAggregate(ROW_NUMBER(*) … UNBOUNDED PRECEDING .. CURRENT ROW)
>    +- Sort(b ASC, c DESC)
>       +- Exchange(hash[b])
> {code}
> Streaming plan:
> {code:SQL}
> Rank(rankType=[ROW_NUMBER], rankRange=[1,1], partitionBy=[b], orderBy=[c DESC])
> {code}



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