OutputFormat (Hadoop 1.2.1 API)
Date: 2013-07-22

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## org.apache.hadoop.mapred
Interface OutputFormat<K,V>

All Known Implementing Classes:
  DBOutputFormat, FileOutputFormat, IndexUpdateOutputFormat, MapFileOutputFormat, MultipleOutputFormat, MultipleSequenceFileOutputFormat, MultipleTextOutputFormat, NullOutputFormat, SequenceFileAsBinaryOutputFormat, SequenceFileOutputFormat, TeraOutputFormat, TextOutputFormat

    public interface OutputFormat<K,V>

`OutputFormat` describes the output-specification for a Map-Reduce job.

The Map-Reduce framework relies on the `OutputFormat` of the job to:

1. Validate the output-specification of the job. For e.g. check that the output directory doesn't already exist.
2. Provide the `RecordWriter` implementation to be used to write out the output files of the job. Output files are stored in a `FileSystem`.

See Also:
  `RecordWriter`, `JobConf`

Method Summary
`void` | `checkOutputSpecs(FileSystem ignored, JobConf job)` Check for validity of the output-specification for the job.
`RecordWriter<K,V>` | `getRecordWriter(FileSystem ignored, JobConf job, String name, Progressable progress)` Get the `RecordWriter` for the given job.

Method Detail

### getRecordWriter

    RecordWriter<K,V> getRecordWriter(FileSystem ignored,
                                      JobConf job,
                                      String name,
                                      Progressable progress)
                                      throws IOException

  Get the `RecordWriter` for the given job.

  Parameters:
    `ignored` -
    `job` - configuration for 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` to write the output for the job.
  Throws:
    `IOException`

### checkOutputSpecs

    void checkOutputSpecs(FileSystem ignored,
                          JobConf job)
                          throws IOException

  Check for validity of the output-specification for the job.

  This is to validate the output specification for the job when it is 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.

  Parameters:
    `ignored` -
    `job` - job configuration.
  Throws:
    `IOException` - when output should not be attempted

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