Ioana Delaney created SPARK-23756:
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Summary: [Performance] Redundant join elimination
Key: SPARK-23756
URL: https://issues.apache.org/jira/browse/SPARK-23756
Project: Spark
Issue Type: Sub-task
Components: SQL
Affects Versions: 3.0.0
Reporter: Ioana Delaney
This rewrite eliminates self-joins on unique keys. Self-joins may be introduced
after view expansion.
*User view:*
{code}
create view manager(mgrno, income) as
select e.empno, e.salary + e.bonus
from employee e, department d
where e.empno = d.mgrno;
{code}
*User query:*
{code}
select e.empname, e.empno
from employee e, manager m
where e.empno = m.mgrno and m.income > 100K
{code}
*Internal query after view expansion:*
{code}
select e.lastname, e.empno
from employee e, employee m, department d
where e.empno = m.empno /* PK = PK */ and e.empno = d.mgrno and
m.salary + m.bonus > 100K
{code}
*Internal query after join elimination:*
{code}
select e.lastname, e.empno
from employee e, department d
where e.empno = d.mgrno and
e.salary + e.bonus > 100K
{code}
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