日志
Hive 源码- GenericUDAFRowNumber.java
/**
* 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, <em>Version</em> 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
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*/
package org.apache.hadoop.hive.ql.udf.generic;
import java.util.ArrayList;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDFArgumentTypeException;
import org.apache.hadoop.hive.ql.exec.WindowFunctionDescription;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.parse.SemanticException;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDAFEvaluator.AggregationBuffer;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.typeinfo.TypeInfo;
import org.apache.hadoop.io.IntWritable;
@WindowFunctionDescription(
description = @Description(
name = "row_number",
value = "_FUNC_() - The ROW_NUMBER function assigns a unique <em>number</em> (sequentially, starting "
+ "from 1, as defined by ORDER BY) to each row within the partition."
),
supportsWindow = false,
pivotResult = true
)
public class GenericUDAFRowNumber extends AbstractGenericUDAFResolver {
static final Log LOG = LogFactory.getLog(GenericUDAFRowNumber.class.getName());
@Override
public GenericUDAFEvaluator getEvaluator(TypeInfo[] parameters) throws SemanticException {
if (parameters.length != 0) {
throw new UDFArgumentTypeException(parameters.length - 1, "No argument is expected.");
}
return new GenericUDAFRowNumberEvaluator();
}
static class RowNumberBuffer implements AggregationBuffer {
ArrayList rowNums;
int nextRow;
void init() {
rowNums = new ArrayList();
}
RowNumberBuffer() {
init();
nextRow = 1;
}
void incr() {
rowNums.add(new IntWritable(nextRow++));
}
}
public static class GenericUDAFRowNumberEvaluator extends GenericUDAFEvaluator {
@Override
public ObjectInspector init(Mode m, ObjectInspector[] parameters) throws HiveException {
super.init(m, parameters);
if (m != Mode.COMPLETE) {
throw new HiveException("Only COMPLETE mode supported for row_number function");
}
return ObjectInspectorFactory.getStandardListObjectInspector(
PrimitiveObjectInspectorFactory.writableIntObjectInspector);
}
@Override
public AggregationBuffer getNewAggregationBuffer() throws HiveException {
return new RowNumberBuffer();
}
@Override
public void reset(AggregationBuffer agg) throws HiveException {
((RowNumberBuffer) agg).init();
}
@Override
public void iterate(AggregationBuffer agg, Object[] parameters) throws HiveException {
((RowNumberBuffer) agg).incr();
}
@Override
public Object terminatePartial(AggregationBuffer agg) throws HiveException {
throw new HiveException("terminatePartial not supported");
}
@Override
public void merge(AggregationBuffer agg, Object partial) throws HiveException {
throw new HiveException("merge not supported");
}
@Override
public Object terminate(AggregationBuffer agg) throws HiveException {
return ((RowNumberBuffer) agg).rowNums;
}
}
}
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