[jira] [Created] (CALCITE-894) Do not generate redundant column alias for the left relation when translating IN subquery

["Maryann Xue (JIRA)" <ji...@apache.org>]

Maryann Xue created CALCITE-894:
-----------------------------------

             Summary: Do not generate redundant column alias for the left relation when translating IN subquery
                 Key: CALCITE-894
                 URL: https://issues.apache.org/jira/browse/CALCITE-894
             Project: Calcite
          Issue Type: Bug
    Affects Versions: 1.4.0-incubating
            Reporter: Maryann Xue
            Assignee: Maryann Xue
            Priority: Minor


{code}
select * from "hr"."emps" where "deptno" in (
  select "deptno" from "hr"."depts")
{code}
would be converted into
{code}
LogicalProject(empid=[$0], deptno=[$1], name=[$2], salary=[$3], commission=[$4])
  LogicalJoin(condition=[=($5, $6)], joinType=[inner])
    LogicalProject($f0=[$0], $f1=[$1], $f2=[$2], $f3=[$3], $f4=[$4], $f5=[$1])
      EnumerableTableScan(table=[[hr, emps]])
    LogicalAggregate(group=[{0}])
      LogicalProject(deptno=[$0])
        EnumerableTableScan(table=[[hr, depts]])
{code}

There is an additional "$f5=[$1]" in the LogicalProject, which might cause us trouble in the later optimization stage. For example if "emps" table had a collation trait on $1, the Project would have multiple collation traits and would be flattened.
Instead, we want the converted rel to be like:
{code}
LogicalProject(empid=[$0], deptno=[$1], name=[$2], salary=[$3], commission=[$4])
  LogicalJoin(condition=[=($1, $5)], joinType=[inner])
    EnumerableTableScan(table=[[hr, emps]])
    LogicalAggregate(group=[{0}])
      LogicalProject(deptno=[$0])
        EnumerableTableScan(table=[[hr, depts]])
{code}




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