[PIG-2118] ClassCastException when using group.$0

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Not A Problem
• Affects Version/s: 0.8.1

Environment

CentOS 5.6

Hadoop 0.20.2
Subversion https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.20 -r 911707
Compiled by chrisdo on Fri Feb 19 08:07:34 UTC 2010

Apache Pig version 0.8.1 (r1094835)
compiled Apr 18 2011, 19:26:53

Also reproduced on:
CentOS 5.5

Apache Pig version 0.8.0-cdh3u0 (rexported)
compiled Mar 25 2011, 16:16:24

Hadoop 0.20.2-CDH3B4
Subversion -r 3aa7c91592ea1c53f3a913a581dbfcdfebe98bfe
Compiled by root on Mon Feb 21 17:31:12 EST 2011
From source with checksum cd3f3059d069da355d3991b499d42c3b

• Assignee: Unassigned
• Reporter: John Amos
• Created: 10/Jun/11 16:26
• Updated: 03/Oct/11 07:40
• Resolved: 03/Oct/11 07:40

Description

Create an input file named "key_only" that contains a single number.

key_only = LOAD 'key_only' AS (theKey: long);
A = GROUP key_only BY theKey;
B = FOREACH A GENERATE group.$0 AS theKey;
dump B;

Processing fails with the following error:

Backend error message
---------------------
java.lang.ClassCastException: java.lang.Long cannot be cast to org.apache.pig.data.Tuple
at org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.POProject.getNext(POProject.java:392)
at org.apache.pig.backend.hadoop.executionengine.physicalLayer.PhysicalOperator.processInput(PhysicalOperator.java:276)
at org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.POProject.getNext(POProject.java:138)
at org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.POProject.getNext(POProject.java:276)
at org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POForEach.processPlan(POForEach.java:345)
at org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POForEach.getNext(POForEach.java:290)
at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapReduce$Reduce.runPipeline(PigMapReduce.java:434)
at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapReduce$Reduce.processOnePackageOutput(PigMapReduce.java:402)
at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapReduce$Reduce.reduce(PigMapReduce.java:382)
at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapReduce$Reduce.reduce(PigMapReduce.java:251)
at org.apache.hadoop.mapreduce.Reducer.run(Reducer.java:176)
at org.apache.hadoop.mapred.ReduceTask.runNewReducer(ReduceTask.java:571)
at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:413)
at org.apache.hadoop.mapred.Child$4.run(Child.java:240)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:396)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1115)
at org.apache.hadoop.mapred.Child.main(Child.java:234)

Issue Links

• is related to: PIG-2087 Not able to project into 'group' tuple from FILTER