[CALCITE-7402] Two-level nested correlated subquery causes TopDownGeneralDecorrelator type mismatch during translation

[silundong]

CALCITE-7402

When D-elimination is triggered during decorrelation, outer variables are replaced with local attributes and constrained with IS_NOT_NULL. The transformation looks like:

Filter(condition=[=($0, $cor0.DEPTNO)])
=>
Filter(condition=[IS_NOT_NULL($0)])

$0 (it's nullable before IS_NOT_NULL) will later be used to replace $cor0.DEPTNO(not nullable). The rewrite itself is fine, but the type inference of Filter does not detect the nullability change implied by the IS_NOT_NULL predicate. That is, $0 is still treated as nullable, which leads to a type mismatch when replacing $cor0.DEPTNO later.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

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