MapReduce示例代码
MapReduce示例代码
/*
* DEMO Map/Reduce class test2
* -- Convert GPDBFormat back to TEXT
*/
public static class Map_test2 extends Mapper<LongWritable, GPDBWritable,
Text, NullWritable> {
public void map(LongWritable key, GPDBWritable value, Context context )
throws IOException {
try {
context.write(new Text(value.toString()), NullWritable.get());
} catch (Exception e) { throw new IOException (e.getMessage()); }
}
}
public static void runTest2() throws Exception{
Configuration conf = new Configuration(true);
Job job = new Job(conf, "test2");
job.setJarByClass(demoMR.class);
job.setInputFormatClass(GPDBInputFormat.class);
job.setOutputKeyLClass (Text.class);
job.setOutputValueClass(NullWritable.class);
job.setOutputFormatClass(TextOutputFormat.class);
job.setMapperClass(Map_test2.class);
GPDBInputFormat.setInputPaths (job,
new Path("/demo/data/writeFromGPDB_42"));
GPDBOutputFormat.setOutputPath(job, new Path("/demo/data/MRTest2"));
job.waitForCompletion(true);
}