org.apache.pig.builtin

Class HiveUDF

java.lang.Object

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

org.apache.pig.builtin.HiveUDF

public class HiveUDF
extends EvalFunc<java.lang.Object>

Use Hive UDF or GenericUDF. Example: define sin HiveUDF('sin'); A = load 'mydata' as (num:double); B = foreach A generate sin(num); HiveUDF takes an optional second parameter if the Hive UDF require constant parameters define in_file HiveUDF('in_file', '(null, "names.txt")');

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
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
HiveUDF(java.lang.String funcName)
HiveUDF(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.
void	finish() Placeholder for cleanup to be performed at the end.
protected static java.lang.String	getErrorMessage(java.lang.Class c)
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

addCredentials, allowCompileTimeCalculation, 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

HiveUDF

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

Throws:

java.io.IOException

java.lang.InstantiationException

java.lang.IllegalAccessException

HiveUDF

public HiveUDF(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

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

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.

Returns:

A list of files

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

finish

public void finish()

Description copied from class: EvalFunc

Placeholder for cleanup to be performed at the end. User defined functions can override. Default implementation is a no-op.

Overrides:

finish in class EvalFunc<java.lang.Object>

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()

getErrorMessage

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