org.apache.hadoop.io

Class SequenceFile.Sorter

java.lang.Object

org.apache.hadoop.io.SequenceFile.Sorter

Enclosing class:

SequenceFile

public static class SequenceFile.Sorter
extends Object

Sorts key/value pairs in a sequence-format file.

For best performance, applications should make sure that the Writable.readFields(DataInput) implementation of their keys is very efficient. In particular, it should avoid allocating memory.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	SequenceFile.Sorter.RawKeyValueIterator The interface to iterate over raw keys/values of SequenceFiles.
class	SequenceFile.Sorter.SegmentDescriptor This class defines a merge segment.

Constructor Summary

Constructors

Constructor and Description
SequenceFile.Sorter(FileSystem fs, Class<? extends WritableComparable> keyClass, Class valClass, Configuration conf) Sort and merge files containing the named classes.
SequenceFile.Sorter(FileSystem fs, RawComparator comparator, Class keyClass, Class valClass, Configuration conf) Sort and merge using an arbitrary RawComparator.
SequenceFile.Sorter(FileSystem fs, RawComparator comparator, Class keyClass, Class valClass, Configuration conf, SequenceFile.Metadata metadata) Sort and merge using an arbitrary RawComparator.

Method Summary

Methods

Modifier and Type	Method and Description
SequenceFile.Writer	cloneFileAttributes(Path inputFile, Path outputFile, Progressable prog) Clones the attributes (like compression of the input file and creates a corresponding Writer
int	getFactor() Get the number of streams to merge at once.
int	getMemory() Get the total amount of buffer memory, in bytes.
SequenceFile.Sorter.RawKeyValueIterator	merge(List<SequenceFile.Sorter.SegmentDescriptor> segments, Path tmpDir) Merges the list of segments of type SegmentDescriptor
SequenceFile.Sorter.RawKeyValueIterator	merge(Path[] inNames, boolean deleteInputs, int factor, Path tmpDir) Merges the contents of files passed in Path[]
SequenceFile.Sorter.RawKeyValueIterator	merge(Path[] inNames, boolean deleteInputs, Path tmpDir) Merges the contents of files passed in Path[] using a max factor value that is already set
void	merge(Path[] inFiles, Path outFile) Merge the provided files.
SequenceFile.Sorter.RawKeyValueIterator	merge(Path[] inNames, Path tempDir, boolean deleteInputs) Merges the contents of files passed in Path[]
void	setFactor(int factor) Set the number of streams to merge at once.
void	setMemory(int memory) Set the total amount of buffer memory, in bytes.
void	setProgressable(Progressable progressable) Set the progressable object in order to report progress.
void	sort(Path[] inFiles, Path outFile, boolean deleteInput) Perform a file sort from a set of input files into an output file.
void	sort(Path inFile, Path outFile) The backwards compatible interface to sort.
SequenceFile.Sorter.RawKeyValueIterator	sortAndIterate(Path[] inFiles, Path tempDir, boolean deleteInput) Perform a file sort from a set of input files and return an iterator.
void	writeFile(SequenceFile.Sorter.RawKeyValueIterator records, SequenceFile.Writer writer) Writes records from RawKeyValueIterator into a file represented by the passed writer

Methods inherited from class java.lang.Object

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

Constructor Detail

SequenceFile.Sorter

public SequenceFile.Sorter(FileSystem fs,
                   Class<? extends WritableComparable> keyClass,
                   Class valClass,
                   Configuration conf)

Sort and merge files containing the named classes.

SequenceFile.Sorter

public SequenceFile.Sorter(FileSystem fs,
                   RawComparator comparator,
                   Class keyClass,
                   Class valClass,
                   Configuration conf)

Sort and merge using an arbitrary RawComparator.

SequenceFile.Sorter

public SequenceFile.Sorter(FileSystem fs,
                   RawComparator comparator,
                   Class keyClass,
                   Class valClass,
                   Configuration conf,
                   SequenceFile.Metadata metadata)

Sort and merge using an arbitrary RawComparator.

Method Detail

setFactor

public void setFactor(int factor)

Set the number of streams to merge at once.

getFactor

public int getFactor()

Get the number of streams to merge at once.

setMemory

public void setMemory(int memory)

Set the total amount of buffer memory, in bytes.

getMemory

public int getMemory()

Get the total amount of buffer memory, in bytes.

setProgressable

public void setProgressable(Progressable progressable)

Set the progressable object in order to report progress.

sort

public void sort(Path[] inFiles,
        Path outFile,
        boolean deleteInput)
          throws IOException

Perform a file sort from a set of input files into an output file.

Parameters:

inFiles - the files to be sorted

outFile - the sorted output file

deleteInput - should the input files be deleted as they are read?

Throws:

IOException

sortAndIterate

public SequenceFile.Sorter.RawKeyValueIterator sortAndIterate(Path[] inFiles,
                                                     Path tempDir,
                                                     boolean deleteInput)
                                                       throws IOException

Perform a file sort from a set of input files and return an iterator.

Parameters:

inFiles - the files to be sorted

tempDir - the directory where temp files are created during sort

deleteInput - should the input files be deleted as they are read?

Returns:

iterator the RawKeyValueIterator

Throws:

IOException

sort

public void sort(Path inFile,
        Path outFile)
          throws IOException

The backwards compatible interface to sort.

Parameters:

inFile - the input file to sort

outFile - the sorted output file

Throws:

IOException

merge

public SequenceFile.Sorter.RawKeyValueIterator merge(List<SequenceFile.Sorter.SegmentDescriptor> segments,
                                            Path tmpDir)
                                              throws IOException

Merges the list of segments of type SegmentDescriptor

Parameters:

segments - the list of SegmentDescriptors

tmpDir - the directory to write temporary files into

Returns:

RawKeyValueIterator

Throws:

IOException

merge

public SequenceFile.Sorter.RawKeyValueIterator merge(Path[] inNames,
                                            boolean deleteInputs,
                                            Path tmpDir)
                                              throws IOException

Merges the contents of files passed in Path[] using a max factor value that is already set

Parameters:

inNames - the array of path names

deleteInputs - true if the input files should be deleted when unnecessary

tmpDir - the directory to write temporary files into

Returns:

RawKeyValueIteratorMergeQueue

Throws:

IOException

merge

public SequenceFile.Sorter.RawKeyValueIterator merge(Path[] inNames,
                                            boolean deleteInputs,
                                            int factor,
                                            Path tmpDir)
                                              throws IOException

Merges the contents of files passed in Path[]

Parameters:

inNames - the array of path names

deleteInputs - true if the input files should be deleted when unnecessary

factor - the factor that will be used as the maximum merge fan-in

tmpDir - the directory to write temporary files into

Returns:

RawKeyValueIteratorMergeQueue

Throws:

IOException

merge

public SequenceFile.Sorter.RawKeyValueIterator merge(Path[] inNames,
                                            Path tempDir,
                                            boolean deleteInputs)
                                              throws IOException

Merges the contents of files passed in Path[]

Parameters:

inNames - the array of path names

tempDir - the directory for creating temp files during merge

deleteInputs - true if the input files should be deleted when unnecessary

Returns:

RawKeyValueIteratorMergeQueue

Throws:

IOException

cloneFileAttributes

public SequenceFile.Writer cloneFileAttributes(Path inputFile,
                                      Path outputFile,
                                      Progressable prog)
                                        throws IOException

Clones the attributes (like compression of the input file and creates a corresponding Writer

Parameters:

inputFile - the path of the input file whose attributes should be cloned

outputFile - the path of the output file

prog - the Progressable to report status during the file write

Returns:

Writer

Throws:

IOException

writeFile

public void writeFile(SequenceFile.Sorter.RawKeyValueIterator records,
             SequenceFile.Writer writer)
               throws IOException

Writes records from RawKeyValueIterator into a file represented by the passed writer

Parameters:

records - the RawKeyValueIterator

writer - the Writer created earlier

Throws:

IOException

merge

public void merge(Path[] inFiles,
         Path outFile)
           throws IOException

Merge the provided files.

Parameters:

inFiles - the array of input path names

outFile - the final output file

Throws:

IOException