org.apache.pig.builtin

Class HiveUDAF

java.lang.Object

org.apache.pig.EvalFunc<java.lang.Object>

org.apache.pig.builtin.HiveUDAF

All Implemented Interfaces:

Algebraic

public class HiveUDAF
extends EvalFunc<java.lang.Object>
implements Algebraic

Use Hive UDAF or GenericUDAF. Example: define avg HiveUDAF('avg'); A = load 'mydata' as (name:chararray, num:double); B = group A by name; C = foreach B generate group, avg(A.num);

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	HiveUDAF.Final
static class	HiveUDAF.Initial
static class	HiveUDAF.Intermediate
protected static class	HiveUDFBase.ConstantObjectInspectInfo
protected static class	HiveUDFBase.HiveReporter A constant of Reporter type that does nothing.

Nested classes/interfaces inherited from class org.apache.pig.EvalFunc

EvalFunc.SchemaType

Field Summary

Fields inherited from class org.apache.pig.EvalFunc

log, pigLogger, reporter, returnType

Constructor Summary

Constructors

Constructor and Description
HiveUDAF(java.lang.String funcName)
HiveUDAF(java.lang.String funcName, java.lang.String params)

Method Summary

Modifier and Type	Method and Description
java.lang.Object	exec(Tuple input) This callback method must be implemented by all subclasses.
protected static java.lang.String	getErrorMessage(java.lang.Class c)
java.lang.String	getFinal() Get the final function.
java.lang.String	getInitial() Get the initial function.
java.lang.String	getIntermed() Get the intermediate function.
java.util.List<java.lang.String>	getShipFiles() Allow a UDF to specify a list of local files it would like placed in the distributed cache.
protected static org.apache.hadoop.hive.ql.exec.MapredContext	instantiateMapredContext()
Schema	outputSchema(Schema input) Report the schema of the output of this UDF.
protected static java.lang.Class	resolveFunc(java.lang.String funcName)

Methods inherited from class org.apache.pig.EvalFunc

allowCompileTimeCalculation, finish, getArgToFuncMapping, getCacheFiles, getInputSchema, getLoadCaster, getLogger, getPigLogger, getReporter, getReturnType, getSchemaName, getSchemaType, isAsynchronous, needEndOfAllInputProcessing, progress, setEndOfAllInput, setInputSchema, setPigLogger, setReporter, setUDFContextSignature, warn

Methods inherited from class java.lang.Object

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

Constructor Detail

HiveUDAF

public HiveUDAF(java.lang.String funcName)
         throws java.io.IOException,
                java.lang.InstantiationException,
                java.lang.IllegalAccessException

Throws:

java.io.IOException

java.lang.InstantiationException

java.lang.IllegalAccessException

HiveUDAF

public HiveUDAF(java.lang.String funcName,
                java.lang.String params)
         throws java.io.IOException,
                java.lang.InstantiationException,
                java.lang.IllegalAccessException

Throws:

java.io.IOException

java.lang.InstantiationException

java.lang.IllegalAccessException

Method Detail

getInitial

public java.lang.String getInitial()

Description copied from interface: Algebraic

Get the initial function.

Specified by:

getInitial in interface Algebraic

Returns:

A function name of f_init. f_init should be an eval func. The return type of f_init.exec() has to be Tuple

getIntermed

public java.lang.String getIntermed()

Description copied from interface: Algebraic

Get the intermediate function.

Specified by:

getIntermed in interface Algebraic

Returns:

A function name of f_intermed. f_intermed should be an eval func. The return type of f_intermed.exec() has to be Tuple

getFinal

public java.lang.String getFinal()

Description copied from interface: Algebraic

Get the final function.

Specified by:

getFinal in interface Algebraic

Returns:

A function name of f_final. f_final should be an eval func parametrized by the same datum as the eval func implementing this interface.

exec

public java.lang.Object exec(Tuple input)
                      throws java.io.IOException

Description copied from class: EvalFunc

This callback method must be implemented by all subclasses. This is the method that will be invoked on every Tuple of a given dataset. Since the dataset may be divided up in a variety of ways the programmer should not make assumptions about state that is maintained between invocations of this method.

Specified by:

exec in class EvalFunc<java.lang.Object>

Parameters:

input - the Tuple to be processed.

Returns:

result, of type T.

Throws:

java.io.IOException

outputSchema

public Schema outputSchema(Schema input)

Description copied from class: EvalFunc

Report the schema of the output of this UDF. Pig will make use of this in error checking, optimization, and planning. The schema of input data to this UDF is provided.

The default implementation interprets the OutputSchema annotation, if one is present. Otherwise, it returns null (no known output schema).

Overrides:

outputSchema in class EvalFunc<java.lang.Object>

Parameters:

input - Schema of the input

Returns:

Schema of the output

resolveFunc

protected static java.lang.Class resolveFunc(java.lang.String funcName)
                                      throws java.io.IOException

Throws:

java.io.IOException

instantiateMapredContext

protected static org.apache.hadoop.hive.ql.exec.MapredContext instantiateMapredContext()

getShipFiles

public java.util.List<java.lang.String> getShipFiles()

Description copied from class: EvalFunc

Allow a UDF to specify a list of local files it would like placed in the distributed cache. These files will be put in the cache for every job the UDF is used in. Check for FuncUtils for utility function to facilitate it The default implementation returns null.

Overrides:

getShipFiles in class EvalFunc<java.lang.Object>

Returns:

A list of files

getErrorMessage

protected static java.lang.String getErrorMessage(java.lang.Class c)