[jira] [Resolved] (CALCITE-896) Remove Aggregate if grouping columns are unique and all functions are splittable

["Haisheng Yuan (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CALCITE-896?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Haisheng Yuan resolved CALCITE-896.
-----------------------------------
       Resolution: Fixed
         Assignee: Haisheng Yuan
    Fix Version/s: 1.20.0

Pushed to master: https://github.com/apache/calcite/commit/3ed76375fd05b29db17d6117aa0487ccb85f45ba

Thanks for your review, [~julianhyde]!

> Remove Aggregate if grouping columns are unique and all functions are splittable
> --------------------------------------------------------------------------------
>
>                 Key: CALCITE-896
>                 URL: https://issues.apache.org/jira/browse/CALCITE-896
>             Project: Calcite
>          Issue Type: Bug
>            Reporter: Julian Hyde
>            Assignee: Haisheng Yuan
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 1.20.0
>
>         Attachments: node.png
>
>          Time Spent: 1h 20m
>  Remaining Estimate: 0h
>
> Remove Aggregate if grouping columns are unique and all functions are splittable. Currently AggregateRemoveRule is only applied if there are no aggregate functions. But we could optimize
> {code}select deptno, count(name) from dept group by deptno{code}
> to
> {code}select deptno, 1 from dept{code}
> because we know deptno is unique, name is not null, and a singleton count applied to a not null column evaluates to 1.
> See AggregateJoinTransposeRule; it already makes use of SqlSplittableAggFunction.



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