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https://issues.apache.org/jira/browse/SPARK-21222?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Gengliang Wang updated SPARK-21222:
-----------------------------------
    Description: 
Move elimination of Distinct clause from analyzer to optimizer

Distinct clause is useless after MAX/MIN clause. For example,
"Select MAX(distinct a) FROM src from"
is equivalent of
"Select MAX(a) FROM src from"
However, this optimization is implemented in analyzer. It should be in 
optimizer.

  was:
Distinct clause is after MAX/MIN clause 
"Select MAX(distinct a) FROM src from"
 is equivalent of 
"Select MAX(distinct a) FROM src from"

However, this optimization is implemented in analyzer. It should be in 
optimizer.


> Move elimination of Distinct clause from analyzer to optimizer
> --------------------------------------------------------------
>
>                 Key: SPARK-21222
>                 URL: https://issues.apache.org/jira/browse/SPARK-21222
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 2.2.0
>            Reporter: Gengliang Wang
>            Priority: Minor
>
> Move elimination of Distinct clause from analyzer to optimizer
> Distinct clause is useless after MAX/MIN clause. For example,
> "Select MAX(distinct a) FROM src from"
> is equivalent of
> "Select MAX(a) FROM src from"
> However, this optimization is implemented in analyzer. It should be in 
> optimizer.



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