org.apache.hadoop.hive.ql.exec.vector.expressions.FuncRandNoSeed Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* 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,
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* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.hive.ql.exec.vector.expressions;
import java.util.Arrays;
import java.util.Random;
import org.apache.hadoop.hive.ql.exec.vector.DoubleColumnVector;
import org.apache.hadoop.hive.ql.exec.vector.VectorExpressionDescriptor;
import org.apache.hadoop.hive.ql.exec.vector.VectorizedRowBatch;
import org.apache.hadoop.hive.ql.metadata.HiveException;
/**
* Implements vectorized rand() function evaluation.
*/
public class FuncRandNoSeed extends VectorExpression {
private static final long serialVersionUID = 1L;
private final Random random;
public FuncRandNoSeed(int outputColumnNum) {
super(-1, outputColumnNum);
random = new Random();
}
public FuncRandNoSeed() {
super();
// Dummy final assignments.
random = null;
}
@Override
public void evaluate(VectorizedRowBatch batch) throws HiveException {
if (childExpressions != null) {
this.evaluateChildren(batch);
}
DoubleColumnVector outputColVector = (DoubleColumnVector) batch.cols[outputColumnNum];
int[] sel = batch.selected;
int n = batch.size;
double[] outputVector = outputColVector.vector;
outputColVector.isRepeating = false;
boolean[] outputIsNull = outputColVector.isNull;
/*
* Do careful maintenance of the outputColVector.noNulls flag.
*/
// return immediately if batch is empty
if (n == 0) {
return;
}
if (batch.selectedInUse) {
// CONSIDER: For large n, fill n or all of isNull array and use the tighter ELSE loop.
if (!outputColVector.noNulls) {
for(int j = 0; j != n; j++) {
final int i = sel[j];
// Set isNull before call in case it changes it mind.
outputIsNull[i] = false;
outputVector[i] = random.nextDouble();
}
} else {
for(int j = 0; j != n; j++) {
final int i = sel[j];
outputVector[i] = random.nextDouble();
}
}
} else {
if (!outputColVector.noNulls) {
// Assume it is almost always a performance win to fill all of isNull so we can
// safely reset noNulls.
Arrays.fill(outputIsNull, false);
outputColVector.noNulls = true;
}
for(int i = 0; i != n; i++) {
outputVector[i] = random.nextDouble();
}
}
}
@Override
public VectorExpressionDescriptor.Descriptor getDescriptor() {
return (new VectorExpressionDescriptor.Builder())
.setMode(
VectorExpressionDescriptor.Mode.PROJECTION)
.setNumArguments(0)
.setArgumentTypes(
VectorExpressionDescriptor.ArgumentType.NONE)
.setInputExpressionTypes(
VectorExpressionDescriptor.InputExpressionType.NONE).build();
}
@Override
public String vectorExpressionParameters() {
return null;
}
}