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https://issues.apache.org/jira/browse/CALCITE-4805?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17420476#comment-17420476
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Julian Hyde commented on CALCITE-4805:
--------------------------------------
It seems that you didn't break any of the tests added in CALCITE-373 and the
change is sound.
But if you are tearing down a fence (see [Chesterton's
fence|https://medium.com/@BrandonBryson/assessing-legacy-code-using-chestertons-fence-38b299aa472f])
- in the case one old line of code - you have to demonstrate that you
understand why it existed. Your explanation needs to contain elements like "it
currently does A but I think it should do B which is better because C and both
are equivalent because D".
> The IN sub-query can't be converted to OR when value list contains Null.
> ------------------------------------------------------------------------
>
> Key: CALCITE-4805
> URL: https://issues.apache.org/jira/browse/CALCITE-4805
> Project: Calcite
> Issue Type: Bug
> Reporter: duan xiong
> Assignee: duan xiong
> Priority: Major
>
> for example:
> {code:java}
> select * from emp where deptno in (null,2){code}
> Now the RelNode is:
> {code:java}
> LogicalProject(EMPNO=[$0], ENAME=[$1], JOB=[$2], MGR=[$3], HIREDATE=[$4],
> SAL=[$5], COMM=[$6], DEPTNO=[$7], SLACKER=[$8])
> LogicalJoin(condition=[=($7, $9)], joinType=[inner])
> LogicalTableScan(table=[[CATALOG, SALES, EMP]])
> LogicalAggregate(group=[{0}])
> LogicalValues(tuples=[[{ null }, { 2 }]]){code}
> The RelNode should be:
> {code:java}
> LogicalProject(EMPNO=[$0], ENAME=[$1], JOB=[$2], MGR=[$3], HIREDATE=[$4],
> SAL=[$5], COMM=[$6], DEPTNO=[$7], SLACKER=[$8])
> LogicalFilter(condition=[OR(=($7, null), =($7, 2))])
> LogicalTableScan(table=[[CATALOG, SALES, EMP]]){code}
> So I think when the sub-query value list size is under the
> threshold(IN_SUB_QUERY_THRESHOLD), they can be converted to OR(no matter have
> the NullLiteral or not).
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