datafu.pig.bags

Class BagJoin

java.lang.Object

org.apache.pig.EvalFunc<T>

datafu.pig.util.ContextualEvalFunc<T>

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

datafu.pig.bags.BagJoin

Direct Known Subclasses:

BagLeftOuterJoin

public class BagJoin
extends AliasableEvalFunc<org.apache.pig.data.DataBag>

Performs an in-memory join across multiple bags.

The format for invocation is BagJoin(bag, 'key',....). This UDF expects that all bags are non-null and that there is a corresponding key for each bag. The key that is expected is the alias of the key inside of the preceding bag. By default, an 'inner' join is performed. You can also perform 'left' or 'full' outer joins by specifying 'left' or 'full' in the definition.

Example: define BagJoin datafu.pig.bags.BagJoin(); -- inner join -- describe data: -- data: {bag1: {(key1: chararray,value1: chararray)},bag2: {(key2: chararray,value2: int)}} bag_joined = FOREACH data GENERATE BagJoin(bag1, 'key1', bag2, 'key2') as joined; -- describe bag_joined: -- bag_joined: {joined: {(bag1::key1: chararray, bag1::value1: chararray, bag2::key2: chararray, bag2::value2: int)}}

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	BagJoin.JoinType

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
BagJoin()
BagJoin(java.lang.String joinType)

Method Summary

Modifier and Type	Method and Description
org.apache.pig.data.DataBag	exec(org.apache.pig.data.Tuple input)
org.apache.pig.impl.logicalLayer.schema.Schema	getOutputSchema(org.apache.pig.impl.logicalLayer.schema.Schema input) Specify the output schema as in {link EvalFunc#outputSchema(Schema)}.

Methods inherited from class datafu.pig.util.AliasableEvalFunc

getBag, getBoolean, getDouble, getDouble, getFieldAliases, getFloat, getFloat, getInteger, getInteger, getLong, getLong, getObject, getPosition, getPosition, getPrefixedAliasName, getString, getString, outputSchema

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, getReturnType, 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

BagJoin

public BagJoin()

BagJoin

public BagJoin(java.lang.String joinType)

Method Detail

exec

public org.apache.pig.data.DataBag exec(org.apache.pig.data.Tuple input)
                                 throws java.io.IOException

Specified by:

exec in class org.apache.pig.EvalFunc<org.apache.pig.data.DataBag>

Throws:

java.io.IOException

getOutputSchema

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

Description copied from class: AliasableEvalFunc

Specify the output schema as in {link EvalFunc#outputSchema(Schema)}.

Specified by:

getOutputSchema in class AliasableEvalFunc<org.apache.pig.data.DataBag>

Parameters:

input - input schema

Returns:

outputSchema output schema