org.apache.pig.builtin

Class UniqueID

java.lang.Object

org.apache.pig.EvalFunc<String>

org.apache.pig.builtin.UniqueID

public class UniqueID
extends EvalFunc<String>

UniqueID generates a unique id for each records in the job. This unique id is stable in task retry. Any arguments to the function are ignored. Example: A = load 'mydata' as (name); B = foreach A generate name, UniqueID(); UniqueID takes the form "index-sequence"

Nested Class Summary

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
UniqueID()

Method Summary

Modifier and Type	Method and Description
String	exec(Tuple input) This callback method must be implemented by all subclasses.
Schema	outputSchema(Schema input) Report the schema of the output of this UDF.

Methods inherited from class org.apache.pig.EvalFunc

allowCompileTimeCalculation, finish, getArgToFuncMapping, getCacheFiles, getInputSchema, getLoadCaster, getLogger, getPigLogger, getReporter, getReturnType, getSchemaName, getSchemaType, getShipFiles, 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

UniqueID

public UniqueID()

Method Detail

exec

public String exec(Tuple input)
            throws 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<String>

Parameters:

input - the Tuple to be processed.

Returns:

result, of type T.

Throws:

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<String>

Parameters:

input - Schema of the input

Returns:

Schema of the output