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https://issues.apache.org/jira/browse/FLINK-3942?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15355907#comment-15355907
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ASF GitHub Bot commented on FLINK-3942:
---------------------------------------
Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/2159#discussion_r69039071
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/api/table/table.scala
---
@@ -446,9 +446,9 @@ class Table(
}
/**
- * Intersect two [[Table]]s with duplicate records removed. Intersect
returns rows only
- * from the left table that are identical to a row in the right table.
- * Similar to an SQL INTERSECT. The fields of the two union operations
must fully overlap.
+ * Intersect two [[Table]]s with duplicate records removed. Intersect
returns records that
+ * exist in both tables, and emit exactly once. Similar to an SQL
INTERSECT. The fields of
--- End diff --
I would rephrase this to "Intersect returns records that exist in both
tables. If a record is present one or both tables more than once, it is
returned just once, i.e., the resulting table has no duplicate records."
> 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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