Ioana Delaney created SPARK-23755:
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Summary: [Performance] Distinct elimination
Key: SPARK-23755
URL: https://issues.apache.org/jira/browse/SPARK-23755
Project: Spark
Issue Type: Sub-task
Components: SQL
Affects Versions: 3.0.0
Reporter: Ioana Delaney
The Distinct requirement can be removed if it is proved that the operation
produces unique output.
{code}
select distinct d.deptno /* PK */, e.empname
from employee e, department d
where e.empno = d.mgrno /*PK = FK*/
{code}
*Internal query after rewrite:*
{code}
select d.deptno, e.empname
from employee e, department d
where e.empno = d.mgrno
{code}
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