Programmatically Reading from DFS
Occasionally it become desirable to read an extended amount on data from DFS to configure a mapper/reducer. This can be done by reading a sequenceFile from the DFS during the configure() call to the mapper/reducer.
FileSystem fs = FileSystem.get(conf);
Path path = new Path("/user/jhebert/out/part-00000");
SequenceFile.Reader reader = new SequenceFile.Reader(fs, path, conf);
Text key = new Text();
Text value = new Text();
while (reader.next(key, value)) {
// Do something useful with the data.
}