datafu.pig.bags
Class BagLeftOuterJoin

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.BagLeftOuterJoin

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

Performs an in-memory left outer join across multiple bags.

The format for invocation is BagLeftOuterJoin(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.

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

Author:

wvaughan

Field Summary

Fields inherited from class org.apache.pig.EvalFunc

log, pigLogger, reporter, returnType

Constructor Summary

BagLeftOuterJoin()

Method Summary

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, setUDFContextSignature

Methods inherited from class org.apache.pig.EvalFunc

finish, getArgToFuncMapping, getCacheFiles, getInputSchema, getLogger, getPigLogger, getReporter, getReturnType, getSchemaName, 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

BagLeftOuterJoin

public BagLeftOuterJoin()

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>

Returns:

outputSchema