Shuo Cheng created CALCITE-3893:
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Summary: Sql with GROUP_ID may generate wrong plan
Key: CALCITE-3893
URL: https://issues.apache.org/jira/browse/CALCITE-3893
Project: Calcite
Issue Type: Bug
Components: core
Affects Versions: 1.22.0
Reporter: Shuo Cheng
Fix For: 1.23.0
Consider the following SQL:
{code:java}
select
deptno, group_id() as g, count(*) as c
from emp
group by grouping sets (deptno, (), ())
{code}
the plan after SqlToRel is:
{code:java}
LogicalUnion(all=[true])
LogicalProject(DEPTNO=[$0], G=[0:BIGINT], C=[$1])
LogicalAggregate(group=[{0}], groups=[[{0}, {}]], C=[COUNT()])
LogicalProject(DEPTNO=[$7])
LogicalTableScan(table=[[CATALOG, SALES, EMP]])
LogicalProject(DEPTNO=[$0], G=[1:BIGINT], C=[$1])
LogicalAggregate(group=[{0}], groups=[[{}]], C=[COUNT()])
LogicalProject(DEPTNO=[$7])
LogicalTableScan(table=[[CATALOG, SALES, EMP]])
{code}
I'm afraid there's some semantic problems here. As `groups` of the aggregate is
empty, then what is `$0` meaning in the project above the aggregate. Maybe that
we want is:
{code:java}
LogicalUnion(all=[true])
LogicalProject(DEPTNO=[$0], G=[0:BIGINT], C=[$1])
LogicalAggregate(group=[{0}], groups=[[{0}, {}]], C=[COUNT()])
LogicalProject(DEPTNO=[$7])
LogicalTableScan(table=[[CATALOG, SALES, EMP]])
LogicalProject(DEPTNO=[$0], G=[1:BIGINT], C=[$1])
LogicalAggregate(group=[{0}], groups=[[{0}]], C=[COUNT()])
LogicalProject(DEPTNO=[null])
LogicalTableScan(table=[[CATALOG, SALES, EMP]]){code}
I noticed this is introduced by CALCITE-1824, cc [~donnyzone],
[~vladimirsitnikov].
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