Package org.apache.hadoop.mapreduce.lib.input

Class CombineFileInputFormat<K,V>

java.lang.Object
org.apache.hadoop.mapreduce.InputFormat<K,V>
org.apache.hadoop.mapreduce.lib.input.FileInputFormat<K,V>
org.apache.hadoop.mapreduce.lib.input.CombineFileInputFormat<K,V>
Direct Known Subclasses:
CombineFileInputFormat, CombineSequenceFileInputFormat, CombineTextInputFormat
@Public @Stable public abstract class CombineFileInputFormat<K,V> extends FileInputFormat<K,V>
An abstract InputFormat that returns CombineFileSplit's in InputFormat.getSplits(JobContext) method. Splits are constructed from the files under the input paths. A split cannot have files from different pools. Each split returned may contain blocks from different files. If a maxSplitSize is specified, then blocks on the same node are combined to form a single split. Blocks that are left over are then combined with other blocks in the same rack. If maxSplitSize is not specified, then blocks from the same rack are combined in a single split; no attempt is made to create node-local splits. If the maxSplitSize is equal to the block size, then this class is similar to the default splitting behavior in Hadoop: each block is a locally processed split. Subclasses implement InputFormat.createRecordReader(InputSplit, TaskAttemptContext) to construct RecordReader's for CombineFileSplit's.
See Also:

  • Field Details

  • Constructor Details

    • CombineFileInputFormat

      public CombineFileInputFormat()
      default constructor

  • Method Details

    • setMaxSplitSize

      protected void setMaxSplitSize(long maxSplitSize)
      Specify the maximum size (in bytes) of each split. Each split is approximately equal to the specified size.

    • setMinSplitSizeNode

      protected void setMinSplitSizeNode(long minSplitSizeNode)
      Specify the minimum size (in bytes) of each split per node. This applies to data that is left over after combining data on a single node into splits that are of maximum size specified by maxSplitSize. This leftover data will be combined into its own split if its size exceeds minSplitSizeNode.

    • setMinSplitSizeRack

      protected void setMinSplitSizeRack(long minSplitSizeRack)
      Specify the minimum size (in bytes) of each split per rack. This applies to data that is left over after combining data on a single rack into splits that are of maximum size specified by maxSplitSize. This leftover data will be combined into its own split if its size exceeds minSplitSizeRack.

    • createPool

      protected void createPool(List<PathFilter> filters)
      Create a new pool and add the filters to it. A split cannot have files from different pools.

    • createPool

      protected void createPool(PathFilter... filters)
      Create a new pool and add the filters to it. A pathname can satisfy any one of the specified filters. A split cannot have files from different pools.

    • isSplitable

      protected boolean isSplitable(JobContext context, Path file)
      Description copied from class: FileInputFormat
      Is the given filename splittable? Usually, true, but if the file is stream compressed, it will not be. The default implementation in FileInputFormat always returns true. Implementations that may deal with non-splittable files must override this method. FileInputFormat implementations can override this and return false to ensure that individual input files are never split-up so that Mappers process entire files.
      Overrides:
      isSplitable in class FileInputFormat<K,V>
      Parameters:
      context - the job context
      file - the file name to check
      Returns:
      is this file splitable?

    • 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<K,V>
      Parameters:
      job - the job context
      Returns:
      an array of InputSplits for the job.
      Throws:
      IOException

    • createRecordReader

      public abstract RecordReader<K,V> createRecordReader(InputSplit split, TaskAttemptContext context) throws IOException
      This is not implemented yet.
      Specified by:
      createRecordReader in class InputFormat<K,V>
      Parameters:
      split - the split to be read
      context - the information about the task
      Returns:
      a new record reader
      Throws:
      IOException

    • getFileBlockLocations

      protected BlockLocation[] getFileBlockLocations(FileSystem fs, FileStatus stat) throws IOException
      Throws:
      IOException