[jira] [Comment Edited] (CALCITE-1583) Wrong results for query with correlated subqueries with aggregate subquery expression

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

    [ https://issues.apache.org/jira/browse/CALCITE-1583?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17521958#comment-17521958 ] 

Julian Hyde edited comment on CALCITE-1583 at 4/13/22 9:23 PM:
---------------------------------------------------------------

[~nobigo], Yes, go ahead. Assign it to yourself. Feel free to use my work, if it helps.

For the query given in the description,
{code}
select * from depts where exists (select sum(empno) from emps where depts.deptno = emps.deptno and 1=2)
{code}
I suspect that {{RelMdMinRowCount}} for the subquery will return 1 or more, and therefore the 'exists (subquery)' can safely be converted to 'true'. That optimization might already be present.


was (Author: julianhyde):
[~nobigo], Yes, go ahead. Feel free to use my work, if it helps.

For the query given in the description,
{code}
select * from depts where exists (select sum(empno) from emps where depts.deptno = emps.deptno and 1=2)
{code}
I suspect that {{RelMdMinRowCount}} for the subquery will return 1 or more, and therefore the 'exists (subquery)' can safely be converted to 'true'. That optimization might already be present.

> Wrong results for query with correlated subqueries with aggregate subquery expression
> -------------------------------------------------------------------------------------
>
>                 Key: CALCITE-1583
>                 URL: https://issues.apache.org/jira/browse/CALCITE-1583
>             Project: Calcite
>          Issue Type: Bug
>            Reporter: Vineet Garg
>            Priority: Major
>              Labels: sub-query
>
> Following query produces wrong result:
> {code} select * from depts where exists (select sum(empno) from emps where depts.deptno = emps.deptno and 1=2) {code}
> Expected Result:
> {noformat}
> deptno |   name    
> --------+-----------
>      10 | Sales
>      20 | Marketing
>      30 | Accounts
> (3 rows)
> {noformat}
> Actual results
> {noformat} zero rows {noformat}
> Calcite rewrites such queries into JOIN which ignores the fact that aggregate functions such as {{sum}} always produce one row, effectively making {{EXISTS}} predicate always true.
> Same is the case with {{Scalar}} and {{IN}} sub-queries.



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