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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-3943) Add support for EXCEPT (set minus)
Date Tue, 28 Jun 2016 02:35:57 GMT

    [ https://issues.apache.org/jira/browse/FLINK-3943?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15352233#comment-15352233
] 

ASF GitHub Bot commented on FLINK-3943:
---------------------------------------

Github user wuchong commented on a diff in the pull request:

    https://github.com/apache/flink/pull/2169#discussion_r68689427
  
    --- Diff: docs/apis/table.md ---
    @@ -695,6 +718,30 @@ val result = left.unionAll(right);
         </tr>
     
         <tr>
    +      <td><strong>Minus</strong></td>
    +      <td>
    +        <p>Similar to a SQL EXCEPT clause. Returns elements from the first table
that do not exist in the second table. Both tables must have identical schema(field names
and types).</p>
    +{% highlight scala %}
    +val left = ds1.toTable(tableEnv, 'a, 'b, 'c);
    +val right = ds2.toTable(tableEnv, 'a, 'b, 'c);
    +val result = left.minus(right);
    +{% endhighlight %}
    +      </td>
    +    </tr>
    +
    +    <tr>
    +      <td><strong>UnionAll</strong></td>
    --- End diff --
    
    UnionAll  -> MinusAll


> Add support for EXCEPT (set minus)
> ----------------------------------
>
>                 Key: FLINK-3943
>                 URL: https://issues.apache.org/jira/browse/FLINK-3943
>             Project: Flink
>          Issue Type: New Feature
>          Components: Table API & SQL
>    Affects Versions: 1.1.0
>            Reporter: Fabian Hueske
>            Assignee: Ivan Mushketyk
>            Priority: Minor
>
> Currently, the Table API and SQL do not support EXCEPT.
> EXCEPT can be executed as a coGroup on all fields that forwards records of the first
input if the second input is empty.
> In order to add support for EXCEPT to the Table API and SQL we need to:
> - Implement a {{DataSetMinus}} class that translates an EXCEPT into a DataSet API program
using a coGroup on all fields.
> - Implement a {{DataSetMinusRule}} that translates a Calcite {{LogicalMinus}} into a
{{DataSetMinus}}.
> - Extend the Table API (and validation phase) to provide an except() method.



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