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. }