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From Silvio Di gregorio <silvio.digrego...@gmail.com>
Subject Re: Job MapReduce to populate HBase Table
Date Mon, 13 Apr 2015 12:13:17 GMT
in documentation (http://hbase.apache.org/0.94/book/mapreduce.example.html),
when the Reduce extends the TableReducer class the write method
put the key null, or rather NullWritable like Shahab Say.
However, the error has disappeared when i removed the
"hbase-client-0.96.0-hadoop1.jar" and inserted  "hbase-0.94.6-cdh4.3.0.jar".
Sorry but i don't understand, I knew only that the Context object had not
accepted a PUT where was required WRITABLE with the
"hbase-client-0.96.0-hadoop1.jar" jar in classpath. With the
"hbase-0.94.6-cdh4.3.0.jar" it is possible.

2015-04-13 13:52 GMT+02:00 Jean-Marc Spaggiari <jean-marc@spaggiari.org>:

> Oh, Shahab is write! That's what happend when you write emails before your
> coffee ;) I confused with your "Put" key ;)  Looked to quickly...
>
> JM
>
> 2015-04-13 7:46 GMT-04:00 Shahab Yunus <shahab.yunus@gmail.com>:
>
> > For the null key you should use NullWritable class, as discussed here:
> >
> >
> http://stackoverflow.com/questions/16198752/advantages-of-using-nullwritable-in-hadoop
> >
> > Regards,
> > Shahab
> >
> > On Mon, Apr 13, 2015 at 7:01 AM, Jean-Marc Spaggiari <
> > jean-marc@spaggiari.org> wrote:
> >
> > > Hi Silvio,
> > >
> > > What is the key you try to write into your HBase table? From your code,
> > > sound like you want your key to be null for all your values, which is
> not
> > > possible in HBase.
> > >
> > > JM
> > >
> > > 2015-04-13 6:37 GMT-04:00 Silvio Di gregorio <
> > silvio.digregorio@gmail.com
> > > >:
> > >
> > > > Hi,
> > > > In Reduce phase when i write to Hbase Table "PFTableNa"
> > > > context.write(null , put);
> > > > Eclipse say me:
> > > > *"The method write(ImmutableBytesWritable, Writable) in the type
> > > >
> > >
> >
> TaskInputOutputContext<Text,BytesWritable,ImmutableBytesWritable,Writable>
> > > > is not applicable for the arguments (null, Put)"*
> > > >
> > > > *put *is org
> > > >
> > > >
> > >
> >
> <eclipse-javadoc:%E2%98%82=LoadUnico/C:%5C/Users%5C/sdigregorio%5C/workspace-luna%5C/hbase-client-0.96.0-hadoop1.jar%3Corg>
> > > > .apache
> > > >
> > > >
> > >
> >
> <eclipse-javadoc:%E2%98%82=LoadUnico/C:%5C/Users%5C/sdigregorio%5C/workspace-luna%5C/hbase-client-0.96.0-hadoop1.jar%3Corg.apache>
> > > > .hadoop
> > > >
> > > >
> > >
> >
> <eclipse-javadoc:%E2%98%82=LoadUnico/C:%5C/Users%5C/sdigregorio%5C/workspace-luna%5C/hbase-client-0.96.0-hadoop1.jar%3Corg.apache.hadoop>
> > > > .hbase
> > > >
> > > >
> > >
> >
> <eclipse-javadoc:%E2%98%82=LoadUnico/C:%5C/Users%5C/sdigregorio%5C/workspace-luna%5C/hbase-client-0.96.0-hadoop1.jar%3Corg.apache.hadoop.hbase>
> > > > .client
> > > >
> > > >
> > >
> >
> <eclipse-javadoc:%E2%98%82=LoadUnico/C:%5C/Users%5C/sdigregorio%5C/workspace-luna%5C/hbase-client-0.96.0-hadoop1.jar%3Corg.apache.hadoop.hbase.client>
> > > > .Put
> > > >
> > > >
> > >
> >
> <eclipse-javadoc:%E2%98%82=LoadUnico/C:%5C/Users%5C/sdigregorio%5C/workspace-luna%5C/hbase-client-0.96.0-hadoop1.jar%3Corg.apache.hadoop.hbase.client(Put.class%E2%98%83Put>.Put(byte[]
> > > > row)
> > > > byte[] rowkey = key.getBytes();
> > > > Put put = new Put(rowkey);
> > > >
> > > > the signature of the reduce method:
> > > > reduce( Text key,Iterable<BytesWritable> values, Context context)
> > > >
> > > > and
> > > >
> > > > public static class Reduce extends TableReducer<Text, BytesWritable,
> > > > ImmutableBytesWritable>{
> > > >
> > > > in the main method:
> > > > Configuration conf = HBaseConfiguration.create();
> > > > Job job = new Job(conf, "LetturaFileHDFS2HBase");
> > > > ...
> > > > TableMapReduceUtil.initTableReducerJob("PFTableNa", Reduce.class,
> job);
> > > >
> > > > Thanks a lot
> > > > Silvio
> > > >
> > >
> >
>

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