[jira] [Updated] (CALCITE-5294) Improve PruneEmptyRules join instances to remove join if generates null and one branch is empty

["ASF GitHub Bot (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CALCITE-5294?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

ASF GitHub Bot updated CALCITE-5294:
------------------------------------
    Labels: pull-request-available  (was: )

> Improve PruneEmptyRules join instances to remove join if generates null and one branch is empty
> -----------------------------------------------------------------------------------------------
>
>                 Key: CALCITE-5294
>                 URL: https://issues.apache.org/jira/browse/CALCITE-5294
>             Project: Calcite
>          Issue Type: Improvement
>          Components: core
>            Reporter: Krisztian Kasa
>            Assignee: Krisztian Kasa
>            Priority: Major
>              Labels: pull-request-available
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> If a {{Join}} generates null on the right and the right branch of the join known never produces any rows the join can be replaced with the left branch and a project on top of it which contains the expressions come from the left branch and null constants from the right branch. Example:
> {code:java}
> select * from emp e
> left outer join (select * from dept where false) as d on e.deptno = d.deptno
> {code}
> {code:java}
> select 
>   e.*, 
>   cast(null as <dept_col0_type>) as <dept_col0_name>
>   ... 
>   cast(null as <dept_coln_type>) as <dept_coln_name> 
> from emp
> {code}



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