[jira] [Commented] (CALCITE-7753) CorrelateProjectExtractor corrupts plans with nested Correlates that reuse the same correlation id

["Mihai Budiu (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-7753?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18109551#comment-18109551 ] 

Mihai Budiu commented on CALCITE-7753:
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If this is not a legitimate plan, perhaps the right fix is for the produced to fix it before handing it to Calcite.

Does calcite have a pass to validate a ready-made Rel plan?

> CorrelateProjectExtractor corrupts plans with nested Correlates that reuse the same correlation id
> --------------------------------------------------------------------------------------------------
>
>                 Key: CALCITE-7753
>                 URL: https://issues.apache.org/jira/browse/CALCITE-7753
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>            Reporter: Sergey Nuyanzin
>            Assignee: Sergey Nuyanzin
>            Priority: Major
>              Labels: pull-request-available
>
> {{CorrelateProjectExtractor}} moves correlated expressions from a correlate's right side to its left. If the right side contains a nested correlate reusing the same id (e.g. {{$cor0}}), the extractor also grabs the inner references and adds them to the outer correlate's {{requiredColumns}}. The decorrelated right never produces them, so the plan is inconsistent and {{RelDecorrelator}} fails with an {{AssertionError}}.
> Calcite's SQL translation never nests two correlates sharing one id, so it isn't reachable from SQL; however downstream planners like Flink build this shape.
> Example — outer correlate over {{EMP}} uses {{$cor0.COMM}}, nested correlate over {{DEPT}} reuses {{$cor0}} and uses {{$cor0.DEPTNO}}:
> {noformat}
> LogicalCorrelate(correlation=[$cor0], joinType=[left], requiredColumns=[{6}])
>   LogicalTableScan(table=[[scott, EMP]])
>   LogicalFilter(condition=[IS NULL($cor0.COMM)])
>     LogicalCorrelate(correlation=[$cor0], joinType=[inner], requiredColumns=[{0}])
>       LogicalTableScan(table=[[scott, DEPT]])
>       LogicalFilter(condition=[=($cor0.DEPTNO, $7)])
>         LogicalTableScan(table=[[scott, EMP]])
> {noformat}
> {{decorrelateQuery}} throws {{AssertionError}}, the same plan with a distinct nested id works.



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