org.apache.hadoop.examples.terasort

Class TeraInputFormat

java.lang.Object

org.apache.hadoop.mapreduce.InputFormat<K,V>

org.apache.hadoop.mapreduce.lib.input.FileInputFormat<Text,Text>

org.apache.hadoop.examples.terasort.TeraInputFormat

public class TeraInputFormat
extends FileInputFormat<Text,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.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.hadoop.mapreduce.lib.input.FileInputFormat

FileInputFormat.Counter

Field Summary

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

INPUT_DIR, INPUT_DIR_RECURSIVE, NUM_INPUT_FILES, PATHFILTER_CLASS, SPLIT_MAXSIZE, SPLIT_MINSIZE

Constructor Summary

Constructors

Constructor and Description
TeraInputFormat()

Method Summary

Methods

Modifier and Type	Method and Description
RecordReader<Text,Text>	createRecordReader(InputSplit split, TaskAttemptContext context) Create a record reader for a given split.
List<InputSplit>	getSplits(JobContext job) Generate the list of files and make them into FileSplits.
static void	writePartitionFile(JobContext job, 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, addInputPathRecursively, addInputPaths, computeSplitSize, getBlockIndex, getFormatMinSplitSize, getInputDirRecursive, getInputPathFilter, getInputPaths, getMaxSplitSize, getMinSplitSize, isSplitable, listStatus, makeSplit, setInputDirRecursive, 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(JobContext job,
                      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 RecordReader<Text,Text> createRecordReader(InputSplit split,
                                         TaskAttemptContext context)
                                           throws IOException

Description copied from class: InputFormat

Create a record reader for a given split. The framework will call RecordReader.initialize(InputSplit, TaskAttemptContext) before the split is used.

Specified by:

createRecordReader in class InputFormat<Text,Text>

Parameters:

split - the split to be read

context - the information about the task

Returns:

a new record reader

Throws:

IOException

getSplits

public List<InputSplit> getSplits(JobContext job)
                           throws IOException

Description copied from class: FileInputFormat

Generate the list of files and make them into FileSplits.

Overrides:

getSplits in class FileInputFormat<Text,Text>

Parameters:

job - the job context

Returns:

an array of InputSplits for the job.

Throws:

IOException