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https://issues.apache.org/jira/browse/CALCITE-3036?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16845275#comment-16845275
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Stamatis Zampetakis commented on CALCITE-3036:
----------------------------------------------
The discussion was done as part of the review of
PR[1157|https://github.com/apache/calcite/pull/1157]. I am copying below the
most relevant part for future reference.
zabetak: What I was wondering actually is if we really use variablesSet in the
Join operator? As far as I can see at least in our test suite it is never used.
If there are variables to set we currently use only Correlate . So I was
thinking is that if we keep both Correlate and Join there is no reason to have
variablesSet in the Join operator.
julianhyde: The reason for variablesSet is correlated scalar sub-query in the
ON clause. Similarly Filter needs variablesSet if there is a correlated scalar
sub-query in its condition, and Project needs variablesSet for correlated
scalar sub-query in one of the project expressions. This stuff isn't very well
tested, but it is needed because sub-query can occur anywhere in a query.
> Remove correlate variables from Join
> ------------------------------------
>
> Key: CALCITE-3036
> URL: https://issues.apache.org/jira/browse/CALCITE-3036
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Reporter: Danny Chan
> Assignee: Danny Chan
> Priority: Major
> Fix For: 1.20.0
>
>
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