[jira] [Assigned] (FLINK-16195) [FLINK-16195] [table-planner-blink] append constant fields to unique key set when deriving unique keys in FlinkRelMdUniqueKeys on project

["Jark Wu (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-16195?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jark Wu reassigned FLINK-16195:
-------------------------------

    Assignee: godfrey he

> [FLINK-16195] [table-planner-blink] append constant fields to unique key set when deriving unique keys in FlinkRelMdUniqueKeys on project
> -----------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: FLINK-16195
>                 URL: https://issues.apache.org/jira/browse/FLINK-16195
>             Project: Flink
>          Issue Type: Improvement
>          Components: Table SQL / Planner
>            Reporter: godfrey he
>            Assignee: godfrey he
>            Priority: Major
>
> currently, {{FlinkRelMdUniqueKeys}} only supports deriving unique keys on non-constant fields. such as: {{select a, b, 1, count( * ) from T group by a, b}}, currently the derived unique keys is {{a, b}}. However {{a, b, 1}} is also a unique key, and the result is {{a, b}} and {{a, b, 1}}.
> note: Ideally, the planner does not require the constant key in the unique key set, all constant values are pulled up or removed as much as possible. Supports this improvement to handle some corner cases in cbo.



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