datafu.pig.bags

Class PrependToBag

java.lang.Object

org.apache.pig.EvalFunc<T>

datafu.pig.util.ContextualEvalFunc<T>

datafu.pig.util.SimpleEvalFunc<org.apache.pig.data.DataBag>

datafu.pig.bags.PrependToBag

public class PrependToBag
extends SimpleEvalFunc<org.apache.pig.data.DataBag>

Prepends a tuple to a bag.

N.B. this copies the entire input bag, so don't use it for large bags.

Example:

 
 define PrependToBag datafu.pig.bags.PrependToBag();

 -- input:
 -- ({(1),(2),(3)},(4))
 -- ({(10),(20),(30),(40),(50)},(60))
 input = LOAD 'input' AS (B: bag{T: tuple(v:INT)}, T: tuple(v:INT));

 -- output:
 -- ({(4),(1),(2),(3)})
 -- ({(60),(10),(20),(30),(40),(50)})
 output = FOREACH input GENERATE PrependToBag(B,T) as B;
 
 

Nested Class Summary

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

org.apache.pig.EvalFunc.SchemaType

Field Summary

Fields inherited from class org.apache.pig.EvalFunc

log, pigLogger, reporter, returnType

Constructor Summary

Constructors

Constructor and Description
PrependToBag()

Method Summary

Modifier and Type	Method and Description
org.apache.pig.data.DataBag	call(org.apache.pig.data.DataBag inputBag, org.apache.pig.data.Tuple t)
org.apache.pig.impl.logicalLayer.schema.Schema	outputSchema(org.apache.pig.impl.logicalLayer.schema.Schema input) Override outputSchema so we can verify the input schema at pig compile time, instead of runtime

Methods inherited from class datafu.pig.util.SimpleEvalFunc

exec, getReturnType

Methods inherited from class datafu.pig.util.ContextualEvalFunc

getContextProperties, getInstanceName, getInstanceProperties, onReady, setUDFContextSignature

Methods inherited from class org.apache.pig.EvalFunc

allowCompileTimeCalculation, finish, getArgToFuncMapping, getCacheFiles, getInputSchema, getLogger, getPigLogger, getReporter, getSchemaName, getSchemaType, getShipFiles, isAsynchronous, progress, setInputSchema, setPigLogger, setReporter, warn

Methods inherited from class java.lang.Object

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

Constructor Detail

PrependToBag

public PrependToBag()

Method Detail

call

public org.apache.pig.data.DataBag call(org.apache.pig.data.DataBag inputBag,
                                        org.apache.pig.data.Tuple t)
                                 throws java.io.IOException

Throws:

java.io.IOException

outputSchema

public org.apache.pig.impl.logicalLayer.schema.Schema outputSchema(org.apache.pig.impl.logicalLayer.schema.Schema input)

Description copied from class: SimpleEvalFunc

Override outputSchema so we can verify the input schema at pig compile time, instead of runtime

Overrides:

outputSchema in class SimpleEvalFunc<org.apache.pig.data.DataBag>

Parameters:

input - input schema

Returns:

call to super.outputSchema in case schema was defined elsewhere