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From "Daniel Dai (JIRA)" <j...@apache.org>
Subject [jira] Commented: (PIG-921) Strange use case for Join which produces different results in local and map reduce mode
Date Tue, 13 Oct 2009 22:09:31 GMT

    [ https://issues.apache.org/jira/browse/PIG-921?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12765275#action_12765275
] 

Daniel Dai commented on PIG-921:
--------------------------------

The result should be ((1,a),(1,b)), ((2,aa),(2,bb). Map-reduce mode produces wrong result.

> Strange use case for Join which produces different results in local and map reduce mode
> ---------------------------------------------------------------------------------------
>
>                 Key: PIG-921
>                 URL: https://issues.apache.org/jira/browse/PIG-921
>             Project: Pig
>          Issue Type: Bug
>          Components: impl
>    Affects Versions: 0.3.0
>         Environment: Hadoop 18 and Hadoop 20
>            Reporter: Viraj Bhat
>         Attachments: A.txt, B.txt, joinusecase.pig
>
>
> I have script in this manner, loads from 2 files A.txt and B.txt
> {code}
> A = LOAD 'A.txt' as (a:tuple(a1:int, a2:chararray));
> B = LOAD 'B.txt' as (b:tuple(b1:int, b2:chararray));
> C = JOIN A by a.a1, B by b.b1;
> DESCRIBE C;
> DUMP C;
> {code}
> A.txt contains the following lines:
> {code}
> (1,a)
> (2,aa)
> {code}
> B.txt contains the following lines:
> {code}
> (1,b)
> (2,bb)
> {code}
> Now running the above script in local and map reduce mode on Hadoop 18 & Hadoop 20,
produces the following:
> Hadoop 18
> =====================================================================
> (1,1)
> (2,2)
> =====================================================================
> Hadoop 20
> =====================================================================
> (1,1)
> (2,2)
> =====================================================================
> Local Mode: Pig with Hadoop 18 jar release 
> =====================================================================
> 2009-08-13 17:15:13,473 [main] INFO  org.apache.pig.Main - Logging error messages to:
/homes/viraj/pig-svn/trunk/pigscripts/pig_1250208913472.log
> 09/08/13 17:15:13 INFO pig.Main: Logging error messages to: /homes/viraj/pig-svn/trunk/pigscripts/pig_1250208913472.log
> C: {a: (a1: int,a2: chararray),b: (b1: int,b2: chararray)}
> 2009-08-13 17:15:13,932 [main] ERROR org.apache.pig.tools.grunt.Grunt - ERROR 1002: Unable
to store alias C
> 09/08/13 17:15:13 ERROR grunt.Grunt: ERROR 1002: Unable to store alias C
> Details at logfile: /homes/viraj/pig-svn/trunk/pigscripts/pig_1250208913472.log
> =====================================================================
> Caused by: java.lang.NullPointerException
>         at org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POPackage.getNext(POPackage.java:206)
>         at org.apache.pig.backend.hadoop.executionengine.physicalLayer.PhysicalOperator.processInput(PhysicalOperator.java:231)
>         at org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POForEach.getNext(POForEach.java:191)
>         at org.apache.pig.backend.hadoop.executionengine.physicalLayer.PhysicalOperator.processInput(PhysicalOperator.java:231)
>         at org.apache.pig.backend.local.executionengine.physicalLayer.counters.POCounter.getNext(POCounter.java:71)
>         at org.apache.pig.backend.hadoop.executionengine.physicalLayer.PhysicalOperator.processInput(PhysicalOperator.java:231)
>         at org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POStore.getNext(POStore.java:117)
>         at org.apache.pig.backend.local.executionengine.LocalPigLauncher.runPipeline(LocalPigLauncher.java:146)
>         at org.apache.pig.backend.local.executionengine.LocalPigLauncher.launchPig(LocalPigLauncher.java:109)
>         at org.apache.pig.backend.local.executionengine.LocalExecutionEngine.execute(LocalExecutionEngine.java:165)
>         ... 9 more
> =====================================================================
> Local Mode: Pig with Hadoop 20 jar release
> =====================================================================
> ((1,a),(1,b))
> ((2,aa),(2,bb)
> =====================================================================

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