org.apache.hadoop.hive.ql.udf.generic.GenericUDFBaseNwayCompare Maven / Gradle / Ivy
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package org.apache.hadoop.hive.ql.udf.generic;
import org.apache.hadoop.hive.ql.exec.FunctionRegistry;
import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
import org.apache.hadoop.hive.ql.exec.UDFArgumentLengthException;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorConverters;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorConverters.Converter;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorUtils;
import org.apache.hadoop.hive.serde2.typeinfo.PrimitiveTypeInfo;
import org.apache.hadoop.hive.serde2.typeinfo.TypeInfo;
import org.apache.hadoop.hive.serde2.typeinfo.TypeInfoFactory;
import org.apache.hadoop.hive.serde2.typeinfo.TypeInfoUtils;
/**
* Base class for comparison UDF's (Greatest and Least).
*/
public abstract class GenericUDFBaseNwayCompare extends GenericUDF {
protected transient ObjectInspector[] argumentOIs;
protected transient Converter[] converters;
protected transient ObjectInspector resultOI;
/**
* @return desired comparison (positive for greatest, negative for least)
*/
abstract int getOrder();
@Override
public ObjectInspector initialize(ObjectInspector[] arguments) throws UDFArgumentException {
if (arguments.length < 2) {
throw new UDFArgumentLengthException(getFuncName() + " requires at least 2 arguments, got "
+ arguments.length);
}
if (arguments[0].getCategory() != ObjectInspector.Category.PRIMITIVE) {
throw new UDFArgumentException(getFuncName() + " only takes primitive types, got "
+ arguments[0].getTypeName());
}
argumentOIs = arguments;
converters = new Converter[arguments.length];
TypeInfo commonInfo = TypeInfoUtils.getTypeInfoFromObjectInspector(arguments[0]);
for (int i = 1; i < arguments.length; i++) {
PrimitiveTypeInfo currInfo = (PrimitiveTypeInfo) TypeInfoUtils.getTypeInfoFromObjectInspector(arguments[i]);
commonInfo = FunctionRegistry.getCommonClassForComparison(
commonInfo, currInfo);
}
resultOI = TypeInfoUtils.getStandardWritableObjectInspectorFromTypeInfo(
(commonInfo == null) ?
TypeInfoFactory.doubleTypeInfo : commonInfo);
for (int i = 0; i < arguments.length; i++) {
converters[i] = ObjectInspectorConverters.getConverter(arguments[i], resultOI);
}
return resultOI;
}
@SuppressWarnings({ "rawtypes", "unchecked" })
@Override
public Object evaluate(GenericUDF.DeferredObject[] arguments) throws HiveException {
Object maxV = null;
//for case of conversion, convert both values to common type and then compare.
for (int i = 0; i < arguments.length; i++) {
Object ai = arguments[i].get();
if (ai == null) { //NULL if any of the args are nulls
return null;
}
if (maxV == null) { //First non-null item.
maxV = converters[i].convert(ai);
continue;
}
Object converted = converters[i].convert(ai);
if (converted == null) {
return null;
}
int result = ObjectInspectorUtils.compare(
converted, resultOI,
maxV, resultOI);
if (getOrder() * result > 0) {
maxV = converted;
}
}
return maxV;
}
@Override
public String getDisplayString(String[] children) {
return getStandardDisplayString(getFuncName(), children, ",");
}
}