Job Configuration for MAP only Jobs

[Shuja Rehman <sh...@gmail.com>]

Hi
I want to configure a map only job where i need to read from hbase table 1
and do some processing in mapper and then save to some other hbase table
and i do not need reducer for it. i have configure the job in this way.

Job job = new Job(config, "Detector");
job.setJarByClass(Driver.class);

           s = new Scan(startRow,endRow);


TableMapReduceUtil.initTableMapperJob(Constants.HBASE_MAPPER_TABLE, s,
Mapper.class, Text.class, Result.class, job);

but when i run the job, it is giving following error.

SEVERE: null
org.apache.hadoop.mapred.InvalidJobConfException: Output directory not set.
        at
org.apache.hadoop.mapreduce.lib.output.FileOutputFormat.checkOutputSpecs(FileOutputFormat.java:123)
        at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:827)
        at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:793)
        at java.security.AccessController.doPrivileged(Native Method)
        at javax.security.auth.Subject.doAs(Subject.java:396)


So kindly let me know the solution. is there any other way to achieve
this????


-- 
Regards
Shuja-ur-Rehman Baig
<http://pk.linkedin.com/in/shujamughal>

Re: Job Configuration for MAP only Jobs

[Harsh J <qw...@gmail.com>]

Hello,

On Thu, Feb 24, 2011 at 1:25 AM, Shuja Rehman <sh...@gmail.com> wrote:
> Hi
> I want to configure a map only job where i need to read from hbase table 1
> and do some processing in mapper and then save to some other hbase table
> and i do not need reducer for it. i have configure the job in this way.

When you don't require the use of an OutputFormat, use the
NullOutputFormat as your OutputFormat. It will not check for existence
of output directories, etc.

P.s. There's also a HBaseOutputFormat of sorts, maybe you could check
that out instead as well.

-- 
Harsh J
www.harshj.com