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https://issues.apache.org/jira/browse/CALCITE-2948?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16828880#comment-16828880
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Danny Chan commented on CALCITE-2948:
-------------------------------------

[~hyuan]
{quote}Because the filter should comparing column from 2 different tables, but 
you are comparing 2 columns from the same table.
{quote}
For this plan it is actually correct, cause the <outer table DEPT.deptno> = 
<inner table EMP.deptno> = <inner table EMP.empno - 1>, we can innfer that 
<outer table DEPT.deptno> = <inner table EMP.empno - 1>, which is actually what 
we want.

If we really want to rewrite SubqueryRemoveRule and change the value generation 
logic, i think it's not that easy and huge work to keep the correctness. I 
would glad to join in the work but we really need a good design doc.

> Complicated logical plan generated for in subquery with non-equi condition
> --------------------------------------------------------------------------
>
>                 Key: CALCITE-2948
>                 URL: https://issues.apache.org/jira/browse/CALCITE-2948
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>            Reporter: Haisheng Yuan
>            Assignee: Danny Chan
>            Priority: Major
>              Labels: pull-request-available, sub-query
>          Time Spent: 1h 50m
>  Remaining Estimate: 0h
>
> Repro:
> Add the following test to SqlToRelConverterTest.java.
> {code:java}
> @Test public void testSubQueryIN() {
>     final String sql = "select deptno\n"
>         + "from EMP e\n"
>         + "where deptno in (select deptno\n"
>         + "from EMP where empno=e.empno+1)";
>     sql(sql).ok();
>   }
> {code}
> Plan:
> {code:java}
> LogicalProject(DEPTNO=[$7])
>   LogicalJoin(condition=[AND(=($0, $10), =($7, $9))], joinType=[inner])
>     LogicalTableScan(table=[[CATALOG, SALES, EMP]])
>     LogicalAggregate(group=[{0, 1}])
>       LogicalProject(DEPTNO=[$7], EMPNO0=[$9])
>         LogicalJoin(condition=[=($0, +($9, 1))], joinType=[inner])
>           LogicalTableScan(table=[[CATALOG, SALES, EMP]])
>           LogicalProject(EMPNO=[$0])
>             LogicalTableScan(table=[[CATALOG, SALES, EMP]])
> {code}
> One join would suffice.



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