org.apache.hadoop.mapred
Class OutputFormatBase

java.lang.Object
  org.apache.hadoop.mapred.OutputFormatBase

All Implemented Interfaces:

OutputFormat

Direct Known Subclasses:

MapFileOutputFormat, SequenceFileOutputFormat, TextOutputFormat

public abstract class OutputFormatBase
extends Object
implements OutputFormat

A base class for OutputFormat.

Constructor Summary

OutputFormatBase()

Method Summary

void	checkOutputSpecs(FileSystem ignored, JobConf job) Check whether the output specification for a job is appropriate.
static boolean	getCompressOutput(JobConf conf) Is the reduce output compressed?
static Class	getOutputCompressorClass(JobConf conf, Class defaultValue) Get the codec for compressing the reduce outputs
abstract RecordWriter	getRecordWriter(FileSystem ignored, JobConf job, String name, Progressable progress) Construct a RecordWriter with Progressable.
static void	setCompressOutput(JobConf conf, boolean val) Set whether the output of the reduce is compressed
static void	setOutputCompressorClass(JobConf conf, Class codecClass) Set the given class as the output compression codec.

Methods inherited from class java.lang.Object

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

Constructor Detail

OutputFormatBase

public OutputFormatBase()

Method Detail

setCompressOutput

public static void setCompressOutput(JobConf conf,
                                     boolean val)

Set whether the output of the reduce is compressed

Parameters:

val - the new setting

getCompressOutput

public static boolean getCompressOutput(JobConf conf)

Is the reduce output compressed?

Returns:

true, if the output should be compressed

setOutputCompressorClass

public static void setOutputCompressorClass(JobConf conf,
                                            Class codecClass)

Set the given class as the output compression codec.

Parameters:

conf - the JobConf to modify

codecClass - the CompressionCodec class that will compress the reduce outputs

getOutputCompressorClass

public static Class getOutputCompressorClass(JobConf conf,
                                             Class defaultValue)

Get the codec for compressing the reduce outputs

Parameters:

conf - the Configuration to look in

defaultValue - the value to return if it is not set

Returns:

the CompressionCodec class that should be used to compress the reduce outputs

Throws:

IllegalArgumentException - if the class was specified, but not found

getRecordWriter

public abstract RecordWriter getRecordWriter(FileSystem ignored,
                                             JobConf job,
                                             String name,
                                             Progressable progress)
                                      throws IOException

Description copied from interface: OutputFormat

Construct a RecordWriter with Progressable.

Specified by:

getRecordWriter in interface OutputFormat

job - the job whose output is being written

name - the unique name for this part of the output

progress - mechanism for reporting progress while writing to file

Returns:

a RecordWriter

Throws:

IOException

checkOutputSpecs

public void checkOutputSpecs(FileSystem ignored,
                             JobConf job)
                      throws FileAlreadyExistsException,
                             InvalidJobConfException,
                             IOException

Description copied from interface: OutputFormat

Check whether the output specification for a job is appropriate. Called when a job is submitted. Typically checks that it does not already exist, throwing an exception when it already exists, so that output is not overwritten.

Specified by:

checkOutputSpecs in interface OutputFormat

job - the job whose output will be written

Throws:

IOException - when output should not be attempted

FileAlreadyExistsException

InvalidJobConfException