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https://issues.apache.org/jira/browse/FLINK-3943?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15367640#comment-15367640
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ASF GitHub Bot commented on FLINK-3943:
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Github user twalthr commented on a diff in the pull request:
https://github.com/apache/flink/pull/2169#discussion_r70069883
--- Diff: docs/apis/table.md ---
@@ -536,6 +536,29 @@ Table result = left.unionAll(right);
</tr>
<tr>
+ <td><strong>Minus</strong></td>
+ <td>
+ <p>Similar to a SQL EXCEPT clause. Except returns records from the
first table that do not exist in the second table. Duplicate records in the
first table are returned exactly once, i.e., duplicates are removed. Both
tables must have identical schema, i.e., field names and types.</p>
--- End diff --
"Except returns records" should be "Minus returns records" to be
consistent. I would also use "left/right" table instead of first and second
according to your example code.
> 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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