[jira] [Created] (CALCITE-7702) JoinAggregateTransposeRule produces a non-equivalent plan when the aggregate with empty input and empty group set

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

zzwqqq created CALCITE-7702:
-------------------------------

             Summary: JoinAggregateTransposeRule produces a non-equivalent plan when the aggregate with empty input and empty group set
                 Key: CALCITE-7702
                 URL: https://issues.apache.org/jira/browse/CALCITE-7702
             Project: Calcite
          Issue Type: Bug
            Reporter: zzwqqq


JoinAggregateTransposeRule produces a non-equivalent plan when the aggregate with empty input empty group set

For example, using the SCOTT schema:
{code:sql}
select g.emp_count, d.deptno
from (select count(*) as emp_count from emp where false) g
join (select deptno from dept where deptno = 10) d on true;
{code}
The query returns:
{code:java}
 emp_count | deptno 
-----------+--------
         0 |     10
(1 row)
{code}
The rewritten plan has the same behavior as follow，and returns no rows:
{code:sql}
select count(*) as emp_count, d.deptno
from (select * from emp where false) e
join (select deptno from dept where deptno = 10) d on true
group by d.deptno;

}
{code}
COUNT without GROUP BY returns one row for empty input. After the aggregate is pulled above the join, DEPTNO becomes a group key. An aggregate with a group key returns no rows for empty input.

The rule should not apply in this case unless the aggregate input is known to be non-empty.



--
This message was sent by Atlassian Jira
(v8.20.10#820010)