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From Alex Burkoff <>
Subject RE: ColumnFamilyOutputFormat and mapreduce.output.columnfamilyoutputformat.batch.threshold 0.70beta1
Date Wed, 08 Sep 2010 22:41:57 GMT
With the trunk version and given patches I am now getting following exception:

10/09/08 22:39:14 WARN mapred.LocalJobRunner: job_local_0001
java.lang.ClassCastException: [B cannot be cast to java.nio.ByteBuffer
        at org.apache.cassandra.hadoop.ColumnFamilyRecordWriter.write(
        at org.apache.hadoop.mapred.ReduceTask$NewTrackingRecordWriter.write(
        at org.apache.hadoop.mapreduce.TaskInputOutputContext.write(
        at cassandratest.Main$TReducer.reduce(
        at cassandratest.Main$TReducer.reduce(
        at org.apache.hadoop.mapred.ReduceTask.runNewReducer(
        at org.apache.hadoop.mapred.LocalJobRunner$
10/09/08 22:39:14 INFO mapred.JobClient:  map 100% reduce 0%

From: Jonathan Ellis []
Sent: Wednesday, September 08, 2010 2:26 PM
Subject: Re: ColumnFamilyOutputFormat and mapreduce.output.columnfamilyoutputformat.batch.threshold

Try the patches on (or wait until
they're committed to trunk, then try a nightly build)

On Wed, Sep 8, 2010 at 4:18 PM, Alex Burkoff <> wrote:
> Guys,
> I was testing ColumnFamilyOutputFormat and found that only columns from the last Reduce
> invocation get stored when mapreduce.output.columnfamilyoutputformat.batch.threshold
> the default value. Setting it to 1 changes the behavior, and all data is stored then.
Is it the
> intended behavior, or am I missing something ?
> Best regards,
> Alex Burkoff

Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support

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