org.apache.hadoop.hive.ql.udf.generic

Class GenericUDFRound

java.lang.Object

org.apache.hadoop.hive.ql.udf.generic.GenericUDF

org.apache.hadoop.hive.ql.udf.generic.GenericUDFRound

All Implemented Interfaces:

Closeable, AutoCloseable

Direct Known Subclasses:

GenericUDFBRound

public class GenericUDFRound
extends GenericUDF

Note: rounding function permits rounding off integer digits in decimal numbers, which essentially downgrades the scale to negative territory. However, Hive decimal only allow non-negative scales. This can cause confusion, for example, when a decimal number 1234.567 of type decimal(7,3) is rounded with -2 scale, which produces a decimal number, 1200. The type of the output is decimal(5,0), which does not exactly represents what the number means. Thus, user should be aware of this, and use negative rounding for decimal with caution. However, Hive is in line with the behavior that MYSQL demonstrates. At a certain point, we should probably support negative scale for decimal type. GenericUDFRound.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.hadoop.hive.ql.udf.generic.GenericUDF

GenericUDF.DeferredJavaObject, GenericUDF.DeferredObject

Constructor Summary

Constructors

Constructor and Description
GenericUDFRound()

Method Summary

Modifier and Type	Method and Description
Object	evaluate(GenericUDF.DeferredObject[] arguments) Evaluate the GenericUDF with the arguments.
String	getDisplayString(String[] children) Get the String to be displayed in explain.
ObjectInspector	initialize(ObjectInspector[] arguments) Initialize this GenericUDF.
protected double	round(double input, int scale)
protected DoubleWritable	round(DoubleWritable input, int scale)
protected HiveDecimalWritable	round(HiveDecimalWritable inputDecWritable, int scale)
protected long	round(long input, int scale)

Methods inherited from class org.apache.hadoop.hive.ql.udf.generic.GenericUDF

adapt, checkArgGroups, checkArgPrimitive, checkArgsSize, close, configure, copyToNewInstance, flip, getArgOrder, getConstantBooleanValue, getConstantIntValue, getConstantStringValue, getDateValue, getDoubleValue, getFuncName, getIntervalDayTimeValue, getIntervalYearMonthValue, getIntValue, getLongValue, getRequiredFiles, getRequiredJars, getStandardDisplayString, getStandardDisplayString, getStringValue, getTimestampValue, getUdfName, initializeAndFoldConstants, negative, obtainDateConverter, obtainDoubleConverter, obtainIntConverter, obtainLongConverter, obtainStringConverter, obtainTimestampConverter

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

GenericUDFRound

public GenericUDFRound()

Method Detail

initialize

public ObjectInspector initialize(ObjectInspector[] arguments)
                           throws UDFArgumentException

Description copied from class: GenericUDF

Initialize this GenericUDF. This will be called once and only once per GenericUDF instance.

Specified by:

initialize in class GenericUDF

Parameters:

arguments - The ObjectInspector for the arguments

Returns:

The ObjectInspector for the return value

Throws:

UDFArgumentException - Thrown when arguments have wrong types, wrong length, etc.

evaluate

public Object evaluate(GenericUDF.DeferredObject[] arguments)
                throws HiveException

Description copied from class: GenericUDF

Evaluate the GenericUDF with the arguments.

Specified by:

evaluate in class GenericUDF

Parameters:

arguments - The arguments as DeferedObject, use DeferedObject.get() to get the actual argument Object. The Objects can be inspected by the ObjectInspectors passed in the initialize call.

Returns:

The

Throws:

HiveException

round

protected HiveDecimalWritable round(HiveDecimalWritable inputDecWritable,
                                    int scale)

round

protected long round(long input,
                     int scale)

round

protected double round(double input,
                       int scale)

round

protected DoubleWritable round(DoubleWritable input,
                               int scale)

getDisplayString

public String getDisplayString(String[] children)

Description copied from class: GenericUDF

Get the String to be displayed in explain.

Specified by:

getDisplayString in class GenericUDF