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Posted to issues@flink.apache.org by "godfrey he (Jira)" <ji...@apache.org> on 2020/02/21 04:09:00 UTC

[jira] [Updated] (FLINK-16195) append constant field to unique key set on project when deriving unique keys in FlinkRelMdUniqueKeys

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

godfrey he updated FLINK-16195:
-------------------------------
    Description: 
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.

  was:
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.


> append constant field to unique key set on project when deriving unique keys in FlinkRelMdUniqueKeys
> ----------------------------------------------------------------------------------------------------
>
>                 Key: FLINK-16195
>                 URL: https://issues.apache.org/jira/browse/FLINK-16195
>             Project: Flink
>          Issue Type: Improvement
>          Components: Table SQL / Planner
>            Reporter: 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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