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https://issues.apache.org/jira/browse/CALCITE-7492?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18076962#comment-18076962
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Yu Xu commented on CALCITE-7492:
--------------------------------

Thanks for your suggestions! [~julianhyde]   I have modified the summary, and I 
will pay more attention to these points in the subsequent implementation 
process.

> Support expression that has a constant value within the group involving only 
> GROUP BY keys as aggregate arguments
> -----------------------------------------------------------------------------------------------------------------
>
>                 Key: CALCITE-7492
>                 URL: https://issues.apache.org/jira/browse/CALCITE-7492
>             Project: Calcite
>          Issue Type: Improvement
>          Components: core
>    Affects Versions: 1.41.0
>            Reporter: Yu Xu
>            Assignee: Yu Xu
>            Priority: Major
>
> Sql like:
> {code:java}
> select sal, max(sal + 1) as max_plus from emp group by sal, deptno {code}
> It should be optimized as follows (the calculation of the aggregate function 
> max is not necessary):
> {code:java}
> select sal, sal + 1 as max_plus from emp group by sal, deptno  {code}
> and current plan:
> {code:java}
> LogicalProject(SAL=[$0], MAX_PLUS=[$2])
>   LogicalAggregate(group=[{0, 1}], MAX_PLUS=[MAX($2)])
>     LogicalProject(SAL=[$5], DEPTNO=[$7], $f2=[+($5, 1)])
>       LogicalTableScan(table=[[CATALOG, SALES, EMP]]) {code}
> it may be optimized.



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