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https://issues.apache.org/jira/browse/CALCITE-7196?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18022307#comment-18022307
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Julian Hyde commented on CALCITE-7196:
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Can you give an example SQL query that would benefit from this rewrite rule?
> Create an optimization pass which can convert some cases of Correlate +
> Unnest to Unnest
> ----------------------------------------------------------------------------------------
>
> Key: CALCITE-7196
> URL: https://issues.apache.org/jira/browse/CALCITE-7196
> Project: Calcite
> Issue Type: New Feature
> Components: core
> Affects Versions: 1.40.0
> Reporter: Mihai Budiu
> Assignee: Mihai Budiu
> Priority: Minor
>
> Today UNNEST is always compiled into a Correlate + Unnest.
> Some query plans of this shape can be simplified however:
> {code}
> Project
> Correlate
> LeftInput
> Uncollect
> Project(correlatedVariable) // only one field here
> Values
> {code}
> If the Project only preserves fields from the right-side of the Correlate,
> such plans can be rewritten as
> {code}
> Project
> Uncollect
> LeftInput
> {code}
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