org.apache.hadoop.hive.ql.exec.SelectOperator Maven / Gradle / Ivy
/**
* 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.hadoop.hive.ql.exec;
import java.io.Serializable;
import java.util.Collection;
import java.util.List;
import java.util.concurrent.Future;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hive.conf.HiveConf;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.plan.ExprNodeColumnDesc;
import org.apache.hadoop.hive.ql.plan.ExprNodeDesc;
import org.apache.hadoop.hive.ql.plan.SelectDesc;
import org.apache.hadoop.hive.ql.plan.api.OperatorType;
/**
* Select operator implementation.
*/
public class SelectOperator extends Operator implements Serializable {
private static final long serialVersionUID = 1L;
protected transient ExprNodeEvaluator[] eval;
transient Object[] output;
private transient boolean isSelectStarNoCompute = false;
@Override
protected Collection> initializeOp(Configuration hconf) throws HiveException {
Collection> result = super.initializeOp(hconf);
// Just forward the row as is
if (conf.isSelStarNoCompute()) {
isSelectStarNoCompute = true;
return result;
}
List colList = conf.getColList();
eval = new ExprNodeEvaluator[colList.size()];
for (int i = 0; i < colList.size(); i++) {
assert (colList.get(i) != null);
eval[i] = ExprNodeEvaluatorFactory.get(colList.get(i));
}
if (HiveConf.getBoolVar(hconf, HiveConf.ConfVars.HIVEEXPREVALUATIONCACHE)) {
eval = ExprNodeEvaluatorFactory.toCachedEvals(eval);
}
output = new Object[eval.length];
if (isLogInfoEnabled) {
LOG.info("SELECT " + inputObjInspectors[0].getTypeName());
}
outputObjInspector = initEvaluatorsAndReturnStruct(eval, conf.getOutputColumnNames(),
inputObjInspectors[0]);
return result;
}
@Override
public void process(Object row, int tag) throws HiveException {
if (isSelectStarNoCompute) {
forward(row, inputObjInspectors[tag]);
return;
}
int i = 0;
try {
for (; i < eval.length; ++i) {
output[i] = eval[i].evaluate(row);
}
} catch (HiveException e) {
throw e;
} catch (RuntimeException e) {
throw new HiveException("Error evaluating " + conf.getColList().get(i).getExprString(), e);
}
forward(output, outputObjInspector);
}
/**
* @return the name of the operator
*/
@Override
public String getName() {
return getOperatorName();
}
static public String getOperatorName() {
return "SEL";
}
@Override
public OperatorType getType() {
return OperatorType.SELECT;
}
@Override
public boolean supportSkewJoinOptimization() {
return true;
}
@Override
public boolean columnNamesRowResolvedCanBeObtained() {
return true;
}
@Override
public boolean supportAutomaticSortMergeJoin() {
return true;
}
@Override
public boolean supportUnionRemoveOptimization() {
return true;
}
@Override
public boolean acceptLimitPushdown() {
return true;
}
/**
* Checks whether this select operator does something to the
* input tuples.
*
* @return if it is an identity select operator or not
*/
public boolean isIdentitySelect() {
// Safety check
if(this.getNumParent() != 1) {
return false;
}
if(conf.isSelStarNoCompute()) {
return true;
}
// Check whether the have the same schema
RowSchema orig = this.getSchema();
RowSchema dest = this.getParentOperators().get(0).getSchema();
if(orig.getSignature() == null && dest.getSignature() == null) {
return true;
}
if((orig.getSignature() == null && dest.getSignature() != null) ||
(orig.getSignature() != null && dest.getSignature() == null) ) {
return false;
}
if(orig.getSignature().size() != dest.getSignature().size() ||
orig.getSignature().size() != conf.getColList().size()) {
return false;
}
for(int i=0; i