[jira] [Commented] (CALCITE-2757) DISTINCT not being handled correctly in RelToSqlConverter

["Julian Hyde (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-2757?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16954861#comment-16954861 ] 

Julian Hyde commented on CALCITE-2757:
--------------------------------------

I took a look at this pull request, and rebased as [https://github.com/julianhyde/calcite/tree/2575-select-distinct-over]. Three of the existing tests in RelToSqlConverterTest now produce different SQL, and the SQL doesn't look valid. Can you take a look?

> DISTINCT not being handled correctly in RelToSqlConverter
> ---------------------------------------------------------
>
>                 Key: CALCITE-2757
>                 URL: https://issues.apache.org/jira/browse/CALCITE-2757
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>            Reporter: KrishnaKant Agrawal
>            Priority: Major
>              Labels: pull-request-available
>
>   SELECT DISTINCT sum( x ) OVER (PARTITION BY y) FROM t
> is valid (per SQL standard) but
>   SELECT sum( x ) OVER (PARTITION BY y)
>   FROM t
>   GROUP BY sum( x ) OVER (PARTITION BY y)
> is not. For example, given the query
>   select sum(deptno) over (partition by loc)
>   from dept
>   group by  sum(deptno) over (partition by loc);
> Oracle gives
>   ORA-00934: group function is not allowed here
> Therefore we should generate a sub-query, something like this:
>   SELECT c1
>   FROM (
>     SELECT sum(deptno) OVER (PARTITION BY loc)
>     FROM dept) AS t
>   GROUP BY c1;
>  
> This will be achieved by Adding a new condition for setting the needNew Flag in SqlImplemontor.Builder.builder() as true in case there are Aggregate Expressions being passed as Group By Keys.



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