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https://issues.apache.org/jira/browse/PIG-616?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12865452#action_12865452
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Gianmarco De Francisci Morales commented on PIG-616:
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This issue has been solved in trunk
> Casts to complex types do not work as expected
> ----------------------------------------------
>
> Key: PIG-616
> URL: https://issues.apache.org/jira/browse/PIG-616
> Project: Pig
> Issue Type: Bug
> Components: impl
> Affects Versions: 0.2.0
> Reporter: Santhosh Srinivasan
> Assignee: Alan Gates
>
> When we specify a (complex) type as a column in Pig, the TypeCastInserter
> inserts the appropriate cast for the (complex) type. However, in the
> implementation of POCast.java, when databyte arrays are converted to the
> (complex) types, we invoke the bytesToXXX method.
> For complex types, especially tuples and bags, we do not enforce the typing
> information specified by the user in the AS clause or with the explicit cast
> statement. The implementation solely relies on bytesToXXX to figure out the
> right type.
> An example of a query that fails is given below. Wrt the query, the data is a
> single column that is a bag of integers. The user specifies this bag to be a
> bag of chararray. This conversion is allowed in pig but the implementation
> does not perform the actual cast. Instead the bytesToBag is called on the
> stream. The resulting type is a bag of integers and not a bag of chararray.
> In the subsequent statement the user (correctly) assumes that the conversion
> has been performed but in reality it has not been done. At run time when a
> chararray based operation is performed we see a ClassCastException.
> The notion of a schema has is absent in the physical operators. The
> schema/fieldSchema in the logical layer has to be passed on to the physical
> layer. The schema can be used to perform additional operations like casting,
> etc.
> {code}
> grunt> cat bag.data
> {(1)}
> grunt> a = load 'bag.data' as (b:{t:(c:chararray)});
> grunt> b = foreach a generate flatten(b);
> grunt> c = foreach b generate CONCAT('Hello ', $0);
> grunt> dump c;
> 2009-01-12 10:44:44,417 [main] INFO
> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher
> - 0% complete
> 2009-01-12 10:45:09,439 [main] ERROR
> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher
> - Map reduce job failed
> 2009-01-12 10:45:09,440 [main] ERROR
> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher
> - Job failed!
> 2009-01-12 10:45:09,443 [main] ERROR
> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.Launcher - Error
> message from task (map)
> task_200812151518_9681_m_000000java.lang.ClassCastException:
> java.lang.Integer cannot be cast to java.lang.String
> at org.apache.pig.builtin.StringConcat.exec(StringConcat.java:37)
> at org.apache.pig.builtin.StringConcat.exec(StringConcat.java:31)
> at
> org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.POUserFunc.getNext(POUserFunc.java:185)
> at
> org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.POUserFunc.getNext(POUserFunc.java:259)
> at
> org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POForEach.processPlan(POForEach.java:271)
> at
> org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POForEach.getNext(POForEach.java:197)
> at
> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapBase.runPipeline(PigMapBase.java:187)
> at
> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapBase.map(PigMapBase.java:175)
> at
> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapOnly$Map.map(PigMapOnly.java:65)
> 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:2207)
> ...
> 2009-01-12 10:45:09,448 [main] ERROR org.apache.pig.tools.grunt.Grunt - ERROR
> 1066: Unable to open iterator for alias c
> 2009-01-12 10:45:09,448 [main] ERROR org.apache.pig.tools.grunt.Grunt -
> org.apache.pig.impl.logicalLayer.FrontendException: Unable to open iterator
> for alias c
> at org.apache.pig.PigServer.openIterator(PigServer.java:426)
> at
> org.apache.pig.tools.grunt.GruntParser.processDump(GruntParser.java:271)
> at
> org.apache.pig.tools.pigscript.parser.PigScriptParser.parse(PigScriptParser.java:178)
> at
> org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:84)
> at org.apache.pig.tools.grunt.Grunt.run(Grunt.java:72)
> at org.apache.pig.Main.main(Main.java:302)
> Caused by: java.io.IOException: Job terminated with anomalous status FAILED
> at org.apache.pig.PigServer.openIterator(PigServer.java:420)
> ... 5 more
> {code}
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