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https://issues.apache.org/jira/browse/FLINK-3943?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15356188#comment-15356188
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ASF GitHub Bot commented on FLINK-3943:
---------------------------------------
Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/2169#discussion_r69047875
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/api/table/table.scala
---
@@ -426,6 +426,49 @@ class Table(
}
/**
+ * Set minus between two [[Table]]s. Similar to an SQL EXCEPT ALL.
+ * The fields of the two minus operands must fully overlap.
+ *
+ * Note: Both tables must be bound to the same [[TableEnvironment]].
+ *
+ * Example:
+ *
+ * {{{
+ * left.minusAll(right)
+ * }}}
+ */
+ def minusAll(right: Table): Table = {
+ // check that right table belongs to the same TableEnvironment
+ if (right.tableEnv != this.tableEnv) {
+ throw new ValidationException("Only tables from the same
TableEnvironment can be unioned.")
+ }
+ new Table(tableEnv, SetMinus(logicalPlan, right.logicalPlan,
true).validate(tableEnv))
+ }
+
+ /**
+ * Perform set minus between [[Table]]s with duplicate records removed.
--- End diff --
Please describe the semantics of minus all in more detail:
- records of the first table are returned
- how many identical records are returned
> 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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