org.apache.hadoop.examples.terasort
Class TeraInputFormat

java.lang.Object
  org.apache.hadoop.mapreduce.InputFormat<K,V>
      org.apache.hadoop.mapreduce.lib.input.FileInputFormat<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>
          org.apache.hadoop.examples.terasort.TeraInputFormat

public class TeraInputFormat
extends org.apache.hadoop.mapreduce.lib.input.FileInputFormat<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

An input format that reads the first 10 characters of each line as the key and the rest of the line as the value. Both key and value are represented as Text.

Field Summary

Fields inherited from class org.apache.hadoop.mapreduce.lib.input.FileInputFormat

INPUT_DIR, NUM_INPUT_FILES, PATHFILTER_CLASS, SPLIT_MAXSIZE, SPLIT_MINSIZE

Constructor Summary

TeraInputFormat()

Method Summary

org.apache.hadoop.mapreduce.RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>	createRecordReader(org.apache.hadoop.mapreduce.InputSplit split, org.apache.hadoop.mapreduce.TaskAttemptContext context)
List<org.apache.hadoop.mapreduce.InputSplit>	getSplits(org.apache.hadoop.mapreduce.JobContext job)
protected org.apache.hadoop.mapreduce.lib.input.FileSplit	makeSplit(org.apache.hadoop.fs.Path file, long start, long length, String[] hosts)
static void	writePartitionFile(org.apache.hadoop.mapreduce.JobContext job, org.apache.hadoop.fs.Path partFile) Use the input splits to take samples of the input and generate sample keys.

Methods inherited from class org.apache.hadoop.mapreduce.lib.input.FileInputFormat

addInputPath, addInputPaths, computeSplitSize, getBlockIndex, getFormatMinSplitSize, getInputPathFilter, getInputPaths, getMaxSplitSize, getMinSplitSize, isSplitable, listStatus, setInputPathFilter, setInputPaths, setInputPaths, setMaxInputSplitSize, setMinInputSplitSize

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

TeraInputFormat

public TeraInputFormat()

Method Detail

writePartitionFile

public static void writePartitionFile(org.apache.hadoop.mapreduce.JobContext job,
                                      org.apache.hadoop.fs.Path partFile)
                               throws Throwable

Use the input splits to take samples of the input and generate sample keys. By default reads 100,000 keys from 10 locations in the input, sorts them and picks N-1 keys to generate N equally sized partitions.

Parameters:

job - the job to sample

partFile - where to write the output file to

Throws:

Throwable - if something goes wrong

createRecordReader

public org.apache.hadoop.mapreduce.RecordReader<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text> createRecordReader(org.apache.hadoop.mapreduce.InputSplit split,
                                                                                                                        org.apache.hadoop.mapreduce.TaskAttemptContext context)
                                                                                                                 throws IOException

Specified by:

createRecordReader in class org.apache.hadoop.mapreduce.InputFormat<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Throws:

IOException

makeSplit

protected org.apache.hadoop.mapreduce.lib.input.FileSplit makeSplit(org.apache.hadoop.fs.Path file,
                                                                    long start,
                                                                    long length,
                                                                    String[] hosts)

Overrides:

makeSplit in class org.apache.hadoop.mapreduce.lib.input.FileInputFormat<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

getSplits

public List<org.apache.hadoop.mapreduce.InputSplit> getSplits(org.apache.hadoop.mapreduce.JobContext job)
                                                       throws IOException

Overrides:

getSplits in class org.apache.hadoop.mapreduce.lib.input.FileInputFormat<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Throws:

IOException