/***********************************************************************************************************************
* Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
*
* Licensed 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 eu.stratosphere.compiler.dag;
import java.util.Collections;
import java.util.List;
import eu.stratosphere.api.common.operators.SingleInputOperator;
import eu.stratosphere.compiler.DataStatistics;
import eu.stratosphere.compiler.operators.MapDescriptor;
import eu.stratosphere.compiler.operators.OperatorDescriptorSingle;
/**
* The optimizer's internal representation of a <i>Map</i> operator node.
*/
public class MapNode extends SingleInputNode {
/**
* Creates a new MapNode for the given contract.
*
* @param operator The map contract object.
*/
public MapNode(SingleInputOperator<?, ?, ?> operator) {
super(operator);
}
@Override
public String getName() {
return "Map";
}
@Override
protected List<OperatorDescriptorSingle> getPossibleProperties() {
return Collections.<OperatorDescriptorSingle>singletonList(new MapDescriptor());
}
/**
* Computes the estimates for the Map operator.
* We assume that by default, Map takes one value and transforms it into another value.
* The cardinality consequently stays the same.
*/
@Override
protected void computeOperatorSpecificDefaultEstimates(DataStatistics statistics) {
this.estimatedNumRecords = getPredecessorNode().getEstimatedNumRecords();
}
}