Haisheng Yuan created CALCITE-2936:
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Summary: Existential subquery that has aggregate without grouping
key should be simplified
Key: CALCITE-2936
URL: https://issues.apache.org/jira/browse/CALCITE-2936
Project: Calcite
Issue Type: New Feature
Reporter: Haisheng Yuan
An existential subquery whose inner child is an aggregate with no grouping
columns should be simplified to a Boolean constant.
Example:
exists(select sum(i) from X) --> true
not exists(select sum(i) from X) --> false
Repro:
{code:java}
@Test public void testExistentialSubquery() {
final String sql = "SELECT e1.empno\n"
+ "FROM emp e1 where exists\n"
+ "(select avg(sal) from emp e2 where e1.empno = e2.empno )";
sql(sql).decorrelate(true).ok();
}
{code}
We got plan:
{code:java}
LogicalProject(EMPNO=[$0])
LogicalProject(EMPNO=[$0], ENAME=[$1], JOB=[$2], MGR=[$3], HIREDATE=[$4],
SAL=[$5], COMM=[$6], DEPTNO=[$7], SLACKER=[$8], EMPNO0=[CAST($9):INTEGER],
$f1=[CAST($10):BOOLEAN])
LogicalJoin(condition=[=($0, $9)], joinType=[inner])
LogicalTableScan(table=[[CATALOG, SALES, EMP]])
LogicalAggregate(group=[{0}], agg#0=[MIN($1)])
LogicalProject(EMPNO=[$0], $f0=[true])
LogicalAggregate(group=[{0}], EXPR$0=[AVG($1)])
LogicalProject(EMPNO=[$0], SAL=[$5])
LogicalTableScan(table=[[CATALOG, SALES, EMP]])
{code}
The preferred plan should be:
{code:java}
LogicalProject(EMPNO=[$0])
LogicalTableScan(table=[[CATALOG, SALES, EMP]])
{code}
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