[
https://issues.apache.org/jira/browse/HIVE-3199?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13403761#comment-13403761
]
Shengsheng Huang commented on HIVE-3199:
----------------------------------------
This patch handles "select distinct *" at compile time. It added another stage
of AST transformer to replace * with named columns, because GroupBy does not
accept wildcard. Another option is to handle wildcard at runtime. Anyway I
think adding an extra stage of AST transformation for potential optimization or
feature enabling makes sense. We could support NATURAL JOIN in the similar way.
@Namit @JQ What do you think?
> 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.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
