[jira] [Comment Edited] (SPARK-43778) RewriteCorrelatedScalarSubquery should handle duplicate attributes

["Jia Fan (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-43778?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17744875#comment-17744875 ] 

Jia Fan edited comment on SPARK-43778 at 7/20/23 5:07 AM:
----------------------------------------------------------

This ticket already fixed by https://issues.apache.org/jira/browse/SPARK-43838. Should we add backport for this? [~cloud_fan] 


was (Author: fanjia):
This ticket already fixed by https://issues.apache.org/jira/browse/SPARK-43838.

> RewriteCorrelatedScalarSubquery should handle duplicate attributes
> ------------------------------------------------------------------
>
>                 Key: SPARK-43778
>                 URL: https://issues.apache.org/jira/browse/SPARK-43778
>             Project: Spark
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 3.4.0
>            Reporter: Andrey Gubichev
>            Priority: Major
>
> This is a correctness problem caused by the fact that the decorrelation rule does not dedup join attributes properly. This leads to the join on (c1 = c1), which is simplified to True and the join becomes a cross product.
>  
> Example query:
>  
> {code:java}
> create view t(c1, c2) as values (0, 1), (0, 2), (1, 2)
> select c1, c2, (select count(*) cnt from t t2 where t1.c1 = t2.c1 having cnt = 0) from t t1
> -- Correct answer: [(0, 1, null), (0, 2, null), (1, 2, null)]
> +---+---+------------------+
> |c1 |c2 |scalarsubquery(c1)|
> +---+---+------------------+
> |0  |1  |null              |
> |0  |1  |null              |
> |0  |2  |null              |
> |0  |2  |null              |
> |1  |2  |null              |
> |1  |2  |null              |
> +---+---+------------------+ {code}
>  
>  
>  



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