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Posted to issues@calcite.apache.org by "duan xiong (Jira)" <ji...@apache.org> on 2021/09/13 00:52:00 UTC
[jira] [Assigned] (CALCITE-4763) EXISTS_AGG, an aggregate function
that returns whether count is positive
[ https://issues.apache.org/jira/browse/CALCITE-4763?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
duan xiong reassigned CALCITE-4763:
-----------------------------------
Assignee: duan xiong
> EXISTS_AGG, an aggregate function that returns whether count is positive
> ------------------------------------------------------------------------
>
> 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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