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https://issues.apache.org/jira/browse/FLINK-3943?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15356209#comment-15356209
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ASF GitHub Bot commented on FLINK-3943:
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Github user fhueske commented on the issue:
https://github.com/apache/flink/pull/2169
Hi @mushketyk, thanks for the PR! I added a few comments inline.
Best, Fabian
@wuchong, thanks for reviewing!
> 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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