org.apache.hadoop.hive.ql.udf.generic.GenericUDAFLastValue 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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* limitations under the License.
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package org.apache.hadoop.hive.ql.udf.generic;
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.ObjectInspectorUtils;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorUtils.ObjectInspectorCopyOption;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorUtils;
import org.apache.hadoop.hive.serde2.typeinfo.TypeInfo;
import org.apache.hadoop.hive.serde2.typeinfo.TypeInfoFactory;
@WindowFunctionDescription(description = @Description(name = "last_value", value = "_FUNC_(x)"), supportsWindow = true, pivotResult = false, impliesOrder = true)
public class GenericUDAFLastValue extends AbstractGenericUDAFResolver
{
static final Log LOG = LogFactory.getLog(GenericUDAFLastValue.class
.getName());
@Override
public GenericUDAFEvaluator getEvaluator(TypeInfo[] parameters)
throws SemanticException
{
if (parameters.length > 2)
{
throw new UDFArgumentTypeException(2, "At most 2 arguments expected");
}
if ( parameters.length > 1 && !parameters[1].equals(TypeInfoFactory.booleanTypeInfo) )
{
throw new UDFArgumentTypeException(1, "second argument must be a boolean expression");
}
return createEvaluator();
}
protected GenericUDAFLastValueEvaluator createEvaluator()
{
return new GenericUDAFLastValueEvaluator();
}
static class LastValueBuffer implements AggregationBuffer
{
Object val;
boolean firstRow;
boolean skipNulls;
LastValueBuffer()
{
init();
}
void init()
{
val = null;
firstRow = true;
skipNulls = false;
}
}
public static class GenericUDAFLastValueEvaluator extends
GenericUDAFEvaluator
{
ObjectInspector inputOI;
ObjectInspector outputOI;
@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 Rank function");
}
inputOI = parameters[0];
outputOI = ObjectInspectorUtils.getStandardObjectInspector(inputOI,
ObjectInspectorCopyOption.WRITABLE);
return outputOI;
}
@Override
public AggregationBuffer getNewAggregationBuffer() throws HiveException
{
return new LastValueBuffer();
}
@Override
public void reset(AggregationBuffer agg) throws HiveException
{
((LastValueBuffer) agg).init();
}
@Override
public void iterate(AggregationBuffer agg, Object[] parameters)
throws HiveException
{
LastValueBuffer lb = (LastValueBuffer) agg;
if (lb.firstRow )
{
lb.firstRow = false;
if ( parameters.length == 2 )
{
lb.skipNulls = PrimitiveObjectInspectorUtils.getBoolean(
parameters[1],
PrimitiveObjectInspectorFactory.writableBooleanObjectInspector);
}
}
if ( !lb.skipNulls || lb.val != null )
{
lb.val = parameters[0];
}
}
@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
{
LastValueBuffer lb = (LastValueBuffer) agg;
return ObjectInspectorUtils.copyToStandardObject(lb.val, inputOI,
ObjectInspectorCopyOption.WRITABLE);
}
}
}