[jira] [Updated] (HIVE-3199) support select distinct *

["Shengsheng Huang (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-3199?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Shengsheng Huang updated HIVE-3199:
-----------------------------------

    Attachment: HIVE-3199.for0.9.0.patch

Uploaded a patch to enable basic "select distinct *" (patterns like "select distinct * from t", "select distinct t.* from t" or "select distinct * from a join b" are all supported) This patch does not support subqueries - That means "select distinct *" can not be contained in subqueries, or the "from" clause is a subquery. 
                
> support select distinct *
> -------------------------
>
>                 Key: HIVE-3199
>                 URL: https://issues.apache.org/jira/browse/HIVE-3199
>             Project: Hive
>          Issue Type: New Feature
>          Components: Query Processor
>    Affects Versions: 0.9.0
>            Reporter: Shengsheng Huang
>         Attachments: HIVE-3199.for0.9.0.patch
>
>
> Error is reported when running query "select distinct * from t". 
> It is a common feature that is better to be supported.
> Did some investigation about this issue. In current implementation "select distinct a,b,c from t" is translated to "select a,b,c from t group by a,b,c". So select distinct * is translated literally to "select * from group by *". But * is not handled properly when processing groupby expressions. 

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