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From "Alan Gates (JIRA)" <j...@apache.org>
Subject [jira] Assigned: (PIG-595) Use of Combiner causes java.lang.ClassCastException in ForEach
Date Thu, 12 Nov 2009 01:58:40 GMT

     [ https://issues.apache.org/jira/browse/PIG-595?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Alan Gates reassigned PIG-595:
------------------------------

    Assignee: Viraj Bhat

> Use of Combiner causes java.lang.ClassCastException in ForEach
> --------------------------------------------------------------
>
>                 Key: PIG-595
>                 URL: https://issues.apache.org/jira/browse/PIG-595
>             Project: Pig
>          Issue Type: Bug
>          Components: impl
>    Affects Versions: 0.2.0
>            Reporter: Viraj Bhat
>            Assignee: Viraj Bhat
>         Attachments: querypairs.txt
>
>
> The following Pig script causes a ClassCastException when QueryPairs is used in the ForEach
statement. This is due to the use of the combiner.
> {code}
> QueryPairs = load 'querypairs.txt' using PigStorage()  as ( q1: chararray, q2: chararray
);
> describe QueryPairs;
> QueryPairsGrouped = group QueryPairs by ( q1 );
> describe QueryPairsGrouped;
> QueryGroups = foreach QueryPairsGrouped generate
>         group                                 as q1,
>         COUNT(QueryPairs)       as paircount,
>         QueryPairs                        as QueryPairs;
> describe QueryGroups;
> dump QueryGroups;
> {code}
> =================================================================================================================
> 2008-12-31 15:01:48,713 [main] ERROR org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.Launcher
- Error message from task (map) task_200812151518_4922_m_000000java.lang.ClassCastException:
org.apache.pig.data.DefaultDataBag cannot be cast to org.apache.pig.data.Tuple
>         at org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POCombinerPackage.getNext(POCombinerPackage.java:122)
>         at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigCombiner$Combine.processOnePackageOutput(PigCombiner.java:152)
>         at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigCombiner$Combine.reduce(PigCombiner.java:143)
>         at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigCombiner$Combine.reduce(PigCombiner.java:57)
>         at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.combineAndSpill(MapTask.java:904)
>         at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.sortAndSpill(MapTask.java:785)
>         at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.flush(MapTask.java:698)
>         at org.apache.hadoop.mapred.MapTask.run(MapTask.java:228)
>         at org.apache.hadoop.mapred.TaskTracker$Child.main(TaskTracker.java:2207)
> =================================================================================================================

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