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https://issues.apache.org/jira/browse/CALCITE-3399?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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jin xing updated CALCITE-3399:
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Description:
*RelFieldTrimmer#trimFields* provides functionality to trim fields for *UNION,
UNION ALL, INTERSECT, INTERSECT ALL, EXCEPT, EXCEPT ALL;*
But *UNION ALL, INTERSECT, INTERSECT ALL, EXCEPT, EXCEPT ALL* works by checking
duplication. Column pruning on inputs of *SetOp* might lead to different
semantics.
Take below example for illustration
{code:java}
emp0:
name, deptno
"A", 0
"B", 1
emp1:
name, deptno
"C", 0
"D", 2
select deptno from
(select name, deptno from emp0
intersect
select name, deptno from emp1)
{code}
Run above Sql on emp0 and emp1, result is not empty if trim fields on inputs of
INTERSECT, but result is empty if DO NOT trim fields on inputs of INTERSECT
was:
RelFieldTrimmer#trimFields provides functionality to trim fields for UNION,
UNION ALL, INTERSECT, INTERSECT ALL, EXCEPT, EXCEPT ALL;
But UNION ALL, INTERSECT, INTERSECT ALL, EXCEPT, EXCEPT ALL works by checking
duplication. Column pruning on inputs of SetOp might lead to different
semantics.
> RelFieldTrimmer trim fields for UNION, INTERSECT, INTERSECT ALL, EXCEPT,
> EXCEPT ALL
> ---
>
> Key: CALCITE-3399
> URL: https://issues.apache.org/jira/browse/CALCITE-3399
> Project: Calcite
> Issue Type: Bug
> Components: core
>Reporter: jin xing
>Assignee: jin xing
>Priority: Major
>
> *RelFieldTrimmer#trimFields* provides functionality to trim fields for
> *UNION, UNION ALL, INTERSECT, INTERSECT ALL, EXCEPT, EXCEPT ALL;*
> But *UNION ALL, INTERSECT, INTERSECT ALL, EXCEPT, EXCEPT ALL* works by
> checking duplication. Column pruning on inputs of *SetOp* might lead to
> different semantics.
>
> Take below example for illustration
> {code:java}
> emp0:
> name, deptno
> "A", 0
> "B", 1
> emp1:
> name, deptno
> "C", 0
> "D", 2
> select deptno from
> (select name, deptno from emp0
> intersect
> select name, deptno from emp1)
> {code}
> Run above Sql on emp0 and emp1, result is not empty if trim fields on inputs
> of INTERSECT, but result is empty if DO NOT trim fields on inputs of INTERSECT
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