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https://issues.apache.org/jira/browse/PIG-919?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12789016#action_12789016
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Alan Gates commented on PIG-919:
--------------------------------

This was closed Fixed when it should have been closed Won't Fix or Later.  No 
patch was checked in for it.  Where are you seeing this error?  In general Pig 
Latin does not allow users to declare the type of map values, so you have to 
explicitly cast map values if you want to group by them so that Pig knows how 
to set the key in the MR job.

> Type mismatch in key from map: expected 
> org.apache.pig.impl.io.NullableBytesWritable, recieved 
> org.apache.pig.impl.io.NullableText when doing simple group
> ----------------------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: PIG-919
>                 URL: https://issues.apache.org/jira/browse/PIG-919
>             Project: Pig
>          Issue Type: Bug
>          Components: impl
>    Affects Versions: 0.3.0
>            Reporter: Viraj Bhat
>            Assignee: Viraj Bhat
>             Fix For: 0.3.0
>
>         Attachments: GenHashList.java, mapscript.pig, mymapudf.jar
>
>
> I have a Pig script, which takes in a student file and generates a bag of 
> maps.  I later want to group on the value of the key "name0" which 
> corresponds to the first name of the student.
> {code}
> register mymapudf.jar;
> data = LOAD '/user/viraj/studenttab10k' AS 
> (somename:chararray,age:long,marks:float);
> genmap = foreach data generate flatten(mymapudf.GenHashList(somename,' ')) as 
> bp:map[], age, marks;
> getfirstnames = foreach genmap generate bp#'name0' as firstname, age, marks;
> filternonnullfirstnames = filter getfirstnames by firstname is not null;
> groupgenmap = group filternonnullfirstnames by firstname;
> dump groupgenmap;
> {code}
> When I execute this code, I get an error in the Map Phase:
> ===========================================================================================================
> java.io.IOException: Type mismatch in key from map: expected 
> org.apache.pig.impl.io.NullableBytesWritable, recieved 
> org.apache.pig.impl.io.NullableText
>       at 
> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(MapTask.java:415)
>       at 
> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapReduce$Map.collect(PigMapReduce.java:108)
>       at 
> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapBase.runPipeline(PigMapBase.java:253)
>       at 
> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapBase.map(PigMapBase.java:242)
>       at 
> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapReduce$Map.map(PigMapReduce.java:93)
>       at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:47)
>       at org.apache.hadoop.mapred.MapTask.run(MapTask.java:227)
>       at 
> org.apache.hadoop.mapred.TaskTracker$Child.main(TaskTracker.java:2209)
> ===========================================================================================================

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