[jira] [Resolved] (CALCITE-6214) Remove DISTINCT in aggregate function if field is unique

["Jiajun Xie (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CALCITE-6214?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jiajun Xie resolved CALCITE-6214.
---------------------------------
    Fix Version/s: 1.37.0
       Resolution: Fixed

> Remove DISTINCT in aggregate function if field is unique
> --------------------------------------------------------
>
>                 Key: CALCITE-6214
>                 URL: https://issues.apache.org/jira/browse/CALCITE-6214
>             Project: Calcite
>          Issue Type: Improvement
>          Components: core
>            Reporter: Jiajun Xie
>            Assignee: Jiajun Xie
>            Priority: Minor
>              Labels: pull-request-available
>             Fix For: 1.37.0
>
>
> For the sql
> {code:java}
> select count(distinct x) cnt
> from(
>    select distinct sal x from emp
> ) t  {code}
> The distinct that in count can be removed.
> {code:java}
> LogicalAggregate(group=[{}], CNT=[COUNT($0)])
>   LogicalAggregate(group=[{0}])
>     LogicalProject(X=[$5])
>       LogicalTableScan(table=[[CATALOG, SALES, EMP]]) {code}
> But `CoreRules#AGGREGATE_REMOVE` not support it, so there are two DISTINCT.
> {code:java}
> LogicalAggregate(group=[{}], CNT=[COUNT(DISTINCT $0)])
>   LogicalAggregate(group=[{0}])
>     LogicalProject(X=[$5])
>       LogicalTableScan(table=[[CATALOG, SALES, EMP]]) {code}



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