[jira] [Resolved] (CALCITE-3763) RelBuilder.aggregate should prune unused fields from the input, if the input is a Project

["Julian Hyde (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CALCITE-3763?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Julian Hyde resolved CALCITE-3763.
----------------------------------
    Fix Version/s: 1.22.0
       Resolution: Fixed

Fixed in [ceb97295|https://github.com/apache/calcite/commit/ceb972952739929c175dfd0895407e8e17e0b502].

> RelBuilder.aggregate should prune unused fields from the input, if the input is a Project
> -----------------------------------------------------------------------------------------
>
>                 Key: CALCITE-3763
>                 URL: https://issues.apache.org/jira/browse/CALCITE-3763
>             Project: Calcite
>          Issue Type: Bug
>            Reporter: Julian Hyde
>            Assignee: Julian Hyde
>            Priority: Major
>             Fix For: 1.22.0
>
>
> {{RelBuilder.aggregate}} should prune unused fields from the input, if the input is a {{Project}}.
> Pruning fields during the planning process is desirable, but often cannot do it - we are applying a {{RelOptRule}} that has to return the same fields, or we don't want to add an extra Project do so the pruning. But when we are in {{RelBuilder.aggregate}} and the input is a Project, neither of those limitations apply. We already have a Project, we are just making it narrower; and we know what fields the {{Aggregate}} will produce.
> For example,
> {code:sql}
> SELECT deptno, SUM(sal) FILTER (WHERE b)
> FROM (
>   SELECT deptno, empno + 10, sal, job = 'CLERK' AS b
>   FROM emp)
> GROUP BY deptno
> {code}
> becomes
> {code:sql}
> SELECT deptno, SUM(sal) FILTER (WHERE b)
> FROM (
>   SELECT deptno, sal, job = 'CLERK' AS b
>   FROM emp)
> GROUP BY deptno
> {code}
> If there are no fields used, remove the {{Project}}. (A {{RelNode}} with no fields is not allowed.)
> {code:sql}
> SELECT COUNT(*) AS C
> FROM (
>  SELECT deptno, empno + 10, sal, job = 'CLERK' AS b
>  FROM emp)
> {code}
> becomes
> {code:sql}
> SELECT COUNT(*) AS c
> FROM emp
> {code}
> Add an option {{RelBuilder.Config.pruneInputOfAggregate}}, default true, so that people can disable this rewrite if it causes problems.



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