org.apache.pig.builtin.SUM 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.pig.builtin;
import java.util.ArrayList;
import java.util.List;
import org.apache.pig.FuncSpec;
import org.apache.pig.data.DataType;
import org.apache.pig.impl.logicalLayer.FrontendException;
import org.apache.pig.impl.logicalLayer.schema.Schema;
/**
* Generates the sum of a set of values. This class implements
* {@link org.apache.pig.Algebraic}, so if possible the execution will
* performed in a distributed fashion.
*
* SUM can operate on any numeric type. It can also operate on bytearrays,
* which it will cast to doubles. It expects a bag of
* tuples of one record each. If Pig knows from the schema that this function
* will be passed a bag of integers or longs, it will use a specially adapted version of
* SUM that uses integer arithmetic for summing the data. The return type
* of SUM is double for float, double, or bytearray arguments and long for int
* or long arguments.
*
* SUM implements the {@link org.apache.pig.Accumulator} interface as well.
* While this will never be
* the preferred method of usage it is available in case the combiner can not be
* used for a given calculation.
*/
public class SUM extends AlgebraicByteArrayMathBase {
public SUM() {
setOp(KNOWN_OP.SUM);
}
public static class Intermediate extends AlgebraicByteArrayMathBase.Intermediate {
@Override
public KNOWN_OP getOp() {
return KNOWN_OP.SUM;
}
}
public static class Final extends AlgebraicByteArrayMathBase.Final {
@Override
public KNOWN_OP getOp() {
return KNOWN_OP.SUM;
}
}
/* (non-Javadoc)
* @see org.apache.pig.EvalFunc#getArgToFuncMapping()
*/
@Override
public List getArgToFuncMapping() throws FrontendException {
List funcList = new ArrayList();
funcList.add(new FuncSpec(this.getClass().getName(), Schema.generateNestedSchema(DataType.BAG, DataType.BYTEARRAY)));
// DoubleSum works for both Floats and Doubles
funcList.add(new FuncSpec(DoubleSum.class.getName(), Schema.generateNestedSchema(DataType.BAG, DataType.DOUBLE)));
funcList.add(new FuncSpec(DoubleSum.class.getName(), Schema.generateNestedSchema(DataType.BAG, DataType.FLOAT)));
// LongSum works for both Ints and Longs.
funcList.add(new FuncSpec(LongSum.class.getName(), Schema.generateNestedSchema(DataType.BAG, DataType.INTEGER)));
funcList.add(new FuncSpec(LongSum.class.getName(), Schema.generateNestedSchema(DataType.BAG, DataType.LONG)));
return funcList;
}
}