[jira] [Created] (SPARK-38832) Remove unnecessary distinct in aggregate expression by distinctKeys

["XiDuo You (Jira)" <ji...@apache.org>]

XiDuo You created SPARK-38832:
---------------------------------

             Summary: Remove unnecessary distinct in aggregate expression by distinctKeys
                 Key: SPARK-38832
                 URL: https://issues.apache.org/jira/browse/SPARK-38832
             Project: Spark
          Issue Type: Improvement
          Components: SQL
    Affects Versions: 3.4.0
            Reporter: XiDuo You


We can remove the distinct in aggregate expression if the child distinct semantics is guaranteed.

For example:

 
{code:java}
SELECT count(distinct c) FROM (
  SELECT c FROM t GROUP BY c
){code}
 

 

 



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