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From Brian Jeltema <brian.jelt...@digitalenvoy.net>
Subject Re: problem with Cassandra map-reduce support
Date Tue, 29 Jan 2013 12:23:39 GMT
In hadoop-0.20.2, org.apache.hadoop.mapreduce.JobContext is a class. Looks like in hadoop-0.21+
JobContext has morphed into an interface.
I'd guess that Hadoop support in Cassandra is based on the older Hadoop.

Brian

On Jan 29, 2013, at 3:42 AM, Tejas Patil wrote:

> I am trying to run a map-reduce job to read data from Cassandra v1.2.0.
> I started off with the code here:
> https://svn.apache.org/repos/asf/cassandra/trunk/examples/hadoop_word_count/src/WordCount.java
> 
> While running it over hadoop-0.22.0, I get this:
> 
> Exception in thread "main" java.lang.IncompatibleClassChangeError: Found interface org.apache.hadoop.mapreduce.JobContext,
but class was expected
> 	at org.apache.cassandra.hadoop.ColumnFamilyInputFormat.getSplits(ColumnFamilyInputFormat.java:103)
> 	at org.apache.hadoop.mapreduce.JobSubmitter.writeNewSplits(JobSubmitter.java:445)
> 	at org.apache.hadoop.mapreduce.JobSubmitter.writeSplits(JobSubmitter.java:462)
> 	at org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:357)
> 	at org.apache.hadoop.mapreduce.Job$2.run(Job.java:1045)
> 	at org.apache.hadoop.mapreduce.Job$2.run(Job.java:1042)
> 	at java.security.AccessController.doPrivileged(Native Method)
> 	at javax.security.auth.Subject.doAs(Subject.java:415)
> 	at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1153)
> 	at org.apache.hadoop.mapreduce.Job.submit(Job.java:1042)
> 	at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:1062)
> 	at MyHadoopApp.run(MyHadoopApp.java:163)
> 	at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:69)
> 	at MyHadoopApp.main(MyHadoopApp.java:82)
> 	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> 	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
> 	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> 	at java.lang.reflect.Method.invoke(Method.java:601)
> 	at org.apache.hadoop.util.RunJar.main(RunJar.java:192)
> 
> Does anyone knows about this ?
> 
> Thanks,
> Tejas Patil


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