[jira] [Commented] (CALCITE-695) SqlSingleValueAggFunction is created when it may not be needed

["Aman Sinha (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-695?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14524265#comment-14524265 ] 

Aman Sinha commented on CALCITE-695:
------------------------------------

It looks like Julian has reviewed this.  I agree with his comments.  [~seanhychu]  I still think that if someone was to accidentally use the new Util.isSingleValue() function for a subquery that had an aggregate function and a group-by and the caller did not check for the grouping list, they would incorrectly get True.  

> SqlSingleValueAggFunction is created when it may not be needed
> --------------------------------------------------------------
>
>                 Key: CALCITE-695
>                 URL: https://issues.apache.org/jira/browse/CALCITE-695
>             Project: Calcite
>          Issue Type: Bug
>    Affects Versions: 1.3.0-incubating
>            Reporter: Aman Sinha
>            Assignee: Julian Hyde
>
> In the following query, the subquery is producing a scalar value but the logical plan still creates a SqlSingleValueAggFunction.   
> {code}
> select r_regionkey from region
>    where r_regionkey > (select min(n_regionkey) * 2 from nation);
> {code}
> If the aggregate is just min(n_regionkey) instead of the expression min(n_regionkey) * 2 then  no SqlSingleValueAggFunction is created.  Ideally, both should behave the same.  
> This is not necessarily a bug but it does create a burden on the underlying execution engine to support this function even in cases where it may not be needed. 



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