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Posted to issues@calcite.apache.org by "duan xiong (Jira)" <ji...@apache.org> on 2021/09/18 11:22:00 UTC

[jira] [Updated] (CALCITE-4763) add EXISTS_AGG aggregate function

     [ https://issues.apache.org/jira/browse/CALCITE-4763?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

duan xiong updated CALCITE-4763:
--------------------------------
    Summary: add EXISTS_AGG aggregate function  (was: EXISTS_AGG, an aggregate function that returns whether count is positive)

> add EXISTS_AGG aggregate function
> ---------------------------------
>
>                 Key: CALCITE-4763
>                 URL: https://issues.apache.org/jira/browse/CALCITE-4763
>             Project: Calcite
>          Issue Type: Bug
>            Reporter: Julian Hyde
>            Assignee: duan xiong
>            Priority: Major
>
> Add {{EXISTS_AGG}}, an aggregate function that returns whether count is greater than zero.
> Thus {{EXISTS_AGG(*)}} is equivalent to {{COUNT(*) > 0}}, and {{EXISTS_AGG(c)}} is equivalent to {{COUNT(c) > 0}}.
> {{EXISTS_AGG}} would mainly be of use internally. Since it produces a {{BOOLEAN}} value, we can use the value directly from an {{Aggregate}} without an intervening {{Project}}. It also captures the fact that we don't care how many rows were produced.
> See also {{TRUE_AGG}}, CALCITE-4334.



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