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https://issues.apache.org/jira/browse/FLINK-3943?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15367668#comment-15367668
]
ASF GitHub Bot commented on FLINK-3943:
---------------------------------------
Github user twalthr commented on a diff in the pull request:
https://github.com/apache/flink/pull/2169#discussion_r70073020
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/api/table/plan/nodes/dataset/DataSetMinus.scala
---
@@ -0,0 +1,150 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.api.table.plan.nodes.dataset
+
+import java.lang.Iterable
+
+import org.apache.calcite.plan.{RelOptCluster, RelOptCost, RelOptPlanner,
RelTraitSet}
+import org.apache.calcite.rel.`type`.RelDataType
+import org.apache.calcite.rel.metadata.RelMetadataQuery
+import org.apache.calcite.rel.{BiRel, RelNode, RelWriter}
+import org.apache.flink.api.common.functions.CoGroupFunction
+import org.apache.flink.api.common.typeinfo.TypeInformation
+import org.apache.flink.api.common.typeutils.CompositeType
+import org.apache.flink.api.java.DataSet
+import org.apache.flink.api.table.BatchTableEnvironment
+import org.apache.flink.util.Collector
+
+import scala.collection.JavaConverters._
+import scala.collection.JavaConversions._
+
+/**
+ * Flink RelNode which matches along with DataSetOperator.
+ *
+ */
+class DataSetMinus(
+ cluster: RelOptCluster,
+ traitSet: RelTraitSet,
+ left: RelNode,
+ right: RelNode,
+ rowType: RelDataType,
+ all: Boolean)
+ extends BiRel(cluster, traitSet, left, right)
+ with DataSetRel {
+
+ override def deriveRowType() = rowType
+
+ override def copy(traitSet: RelTraitSet, inputs:
java.util.List[RelNode]): RelNode = {
+ new DataSetMinus(
+ cluster,
+ traitSet,
+ inputs.get(0),
+ inputs.get(1),
+ rowType,
+ all
+ )
+ }
+
+ override def toString: String = {
+ s"SetMinus(setMinus: ($setMinusSelectionToString}))"
+ }
+
+ override def explainTerms(pw: RelWriter): RelWriter = {
+ super.explainTerms(pw).item("setMinus", setMinusSelectionToString)
+ }
+
+ override def computeSelfCost (planner: RelOptPlanner, metadata:
RelMetadataQuery): RelOptCost = {
+
+ val children = this.getInputs
+ val rowCnt = children.foldLeft(0D) { (rows, child) =>
+ rows + metadata.getRowCount(child)
+ }
+
+ planner.getCostFactory.makeCost(rowCnt, 0, 0)
--- End diff --
Shouldn't the cost be similar to an Intersect because both are using a
CoGroup?
> 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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