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https://issues.apache.org/jira/browse/FLINK-3942?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15348836#comment-15348836
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ASF GitHub Bot commented on FLINK-3942:
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Github user fhueske commented on the issue:
https://github.com/apache/flink/pull/2159
Hi @wuchong, thanks for the PR. I think it is better to use a CoGroup
instead of a Join for `INTERSECT` (even though, I said "Join" in the original
JIRA). For `INTERSECT ALL`, CoGroup is required. It would also be good to
update the Table API and SQL documentation as @mushketyk suggested.
Thanks, Fabian
> Add support for INTERSECT
> -------------------------
>
> Key: FLINK-3942
> URL: https://issues.apache.org/jira/browse/FLINK-3942
> Project: Flink
> Issue Type: New Feature
> Components: Table API & SQL
> Affects Versions: 1.1.0
> Reporter: Fabian Hueske
> Assignee: Jark Wu
> Priority: Minor
>
> Currently, the Table API and SQL do not support INTERSECT.
> INTERSECT can be executed as join on all fields.
> In order to add support for INTERSECT to the Table API and SQL we need to:
> - Implement a {{DataSetIntersect}} class that translates an INTERSECT into a
> DataSet API program using a join on all fields.
> - Implement a {{DataSetIntersectRule}} that translates a Calcite
> {{LogicalIntersect}} into a {{DataSetIntersect}}.
> - Extend the Table API (and validation phase) to provide an intersect()
> method.
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