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From Prakrati Agrawal <Prakrati.Agra...@mu-sigma.com>
Subject Getting Null Pointer Exception when using Map Reduce for retrieval
Date Tue, 26 Jun 2012 07:29:18 GMT
Dear all

I created a database in HBase. First I was retrieving it using Java APIs but it was taking
a lot of time(43 seconds) to retrieve it. I thought of writing Map Reduce code to retrieve
it to make it faster. But I am getting Null Pointer Exception in my code. Following is the
excerpt from my code:

                                                  tableName,        // input HBase table name
                                                  scanRows,             // Scan instance to
control CF and attribute selection
                                                  MyMapper.class,   // mapper
                                                  null,             // mapper output key
                                                  null,             // mapper output value
job.setOutputFormatClass(NullOutputFormat.class);   // because we aren't emitting anything
from mapper

boolean b = job.waitForCompletion(true);
if (!b) {
              throw new IOException("error with job!");

The error I get is as follows:
Exception in thread "main" java.lang.NullPointerException
            at org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil.initTableMapperJob(TableMapReduceUtil.java:100)
            at org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil.initTableMapperJob(TableMapReduceUtil.java:75)

Please help me

Thanks and Regards
Prakrati Agrawal | Developer - Big Data(I&D)| 9731648376 | www.mu-sigma.com

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