Details
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Improvement
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Status: Open
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Major
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Resolution: Unresolved
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None
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None
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Description
For queries such as
select sal from emp where empno IN ( select deptno from dept where emp.job = dept.name)
Filter condition for correlated predicate e.g. =($cor0.JOB, $1) is transformed into equality predicate on same column e.g. $1=$1 after calling decorrelateExpr (if value generator is not generated). This is further simplified into $1 is not null.
We do not need to generate and simplify such predicate expression, instead it could be completely removed. This will help support cases other than equality correlated predicates for which value generated is not required.