[jira] [Comment Edited] (CALCITE-4668) RelBuilder.join should only emit a correlate when a correlate variable is used

["James Starr (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-4668?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17370846#comment-17370846 ] 

James Starr edited comment on CALCITE-4668 at 6/28/21, 11:06 PM:
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{quote}
Where does that scan occur?
{quote}
RelBuilder:2425 before the change, then RelBuilder:3453 after the changes.

{quote}
I disagree. The tests were good enough when written. They produced a plan, which allowed us to check what was going on. They no longer produce a plan, so we have lost test coverage. I cannot go back the original author of those tests, so I am asking you.
{qoute}
I have updated the tests with ORs, however, the correlates are still being rewritten to joins.


was (Author: jamesstarr):
{quote}
Where does that scan occur?
{quote}
RelBuilder:2425 before the change, then RelBuilder:3453 after the changes.

{quote}
I disagree. The tests were good enough when written. They produced a plan, which allowed us to check what was going on. They no longer produce a plan, so we have lost test coverage. I cannot go back the original author of those tests, so I am asking you.

I think if you add one or two queries with in sub-queries and an or condition in the sub-query, you will get similar plans to the ones that just got simplified.
{qoute}
I have updated the tests with ORs, however, the correlates are still being rewritten to joins.

> RelBuilder.join should only emit a correlate when a correlate variable is used
> ------------------------------------------------------------------------------
>
>                 Key: CALCITE-4668
>                 URL: https://issues.apache.org/jira/browse/CALCITE-4668
>             Project: Calcite
>          Issue Type: Improvement
>          Components: core
>            Reporter: James Starr
>            Priority: Major
>              Labels: pull-request-available
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> We generate correlated join when no correlate variable is present on the right side.  However, this could be simplified to emit a normal join.
> Given:
> {code:java}
> final RelNode rel = builder
>     .scan("EMP")
>     .variable(v)
>     .scan("DEPT")
>     .join(JoinRelType.LEFT,
>         builder.equals(builder.field(2, 0, "SAL"),
>             builder.literal(1000)),
>         ImmutableSet.of(v.get().id))
>     .build();
> {code}
> Currently the following is emitted:
> {code}
> LogicalFilter(condition=[=($7, $8)])
>   LogicalCorrelate(correlation=[$cor0], joinType=[left], requiredColumns=[{0}])
>     LogicalTableScan(table=[[scott, EMP]])
>     LogicalFilter(condition=[=($cor0.DEPTNO, $0)])
>       LogicalTableScan(table=[[scott, DEPT]])
> {code}
> After the changes the following will be emitted:
> {code}
> LogicalJoin(condition=[=($7, $8)], joinType=[left])
>   LogicalTableScan(table=[[scott, EMP]])
>   LogicalTableScan(table=[[scott, DEPT]])
> {code}



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