[jira] [Resolved] (CALCITE-3012) Column uniqueness metadata provider may return wrong result for FULL OUTER JOIN operator

["Jesus Camacho Rodriguez (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CALCITE-3012?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jesus Camacho Rodriguez resolved CALCITE-3012.
----------------------------------------------
       Resolution: Fixed
    Fix Version/s: 1.20.0

Fixed in [9ece70f5dcdb00dbc6712496c51f52c05178d4aa|https://github.com/apache/calcite/commit/9ece70f5dcdb00dbc6712496c51f52c05178d4aa]. Thanks [~vgarg]!

> Column uniqueness metadata provider may return wrong result for FULL OUTER JOIN operator
> ----------------------------------------------------------------------------------------
>
>                 Key: CALCITE-3012
>                 URL: https://issues.apache.org/jira/browse/CALCITE-3012
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>            Reporter: Vineet Garg
>            Assignee: Vineet Garg
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 1.20.0
>
>          Time Spent: 2h 20m
>  Remaining Estimate: 0h
>
> Let's say set of columns passed to this API are join keys and there is one NULL key coming from both the inputs. Following code will return true which is wrong because the result of FULL. OUTER JOIN with NULL key on both side will produce two rows with NULL. Even though this value in respective input is unique the result of join may not be unique.
> {code:java}
>  Boolean leftUnique = mq.areColumnsUnique(left, leftColumns, ignoreNulls);
>     Boolean rightUnique = mq.areColumnsUnique(right, rightColumns, ignoreNulls);
>     if ((leftColumns.cardinality() > 0)
>         && (rightColumns.cardinality() > 0)) {
>       if ((leftUnique == null) || (rightUnique == null)) {
>         return null;
>       } else {
>         return leftUnique && rightUnique;
>       }
>     }
> {code}
> {code:sql}
> create table trepro(i int);
> insert into trepro values(null);
> select * from trepro t1 full outer join trepro t2 on t1.i=t2.i;
> null, null
> null, null
> {code}



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