org.apache.hadoop.hbase.util

Class RegionSplitter.UniformSplit

java.lang.Object

org.apache.hadoop.hbase.util.RegionSplitter.UniformSplit

All Implemented Interfaces:

RegionSplitter.SplitAlgorithm

Enclosing class:

RegionSplitter

public static class RegionSplitter.UniformSplit
extends Object
implements RegionSplitter.SplitAlgorithm

A SplitAlgorithm that divides the space of possible keys evenly. Useful when the keys are approximately uniform random bytes (e.g. hashes). Rows are raw byte values in the range 00 => FF and are right-padded with zeros to keep the same memcmp() order. This is the natural algorithm to use for a byte[] environment and saves space, but is not necessarily the easiest for readability.

Field Summary

Fields

Modifier and Type	Field and Description
(package private) byte[]	firstRowBytes
(package private) byte[]	lastRowBytes
(package private) static byte	xFF

Constructor Summary

Constructors

Constructor and Description
UniformSplit()

Method Summary

Modifier and Type	Method and Description
byte[]	firstRow() In HBase, the first row is represented by an empty byte array.
byte[]	lastRow() In HBase, the last row is represented by an empty byte array.
String	rowToStr(byte[] row)
String	separator()
void	setFirstRow(byte[] userInput) Set the first row
void	setFirstRow(String userInput) In HBase, the last row is represented by an empty byte array.
void	setLastRow(byte[] userInput) Set the last row
void	setLastRow(String userInput) In HBase, the last row is represented by an empty byte array.
byte[]	split(byte[] start, byte[] end) Split a pre-existing region into 2 regions.
byte[][]	split(byte[] start, byte[] end, int numSplits, boolean inclusive) Some MapReduce jobs may want to run multiple mappers per region, this is intended for such usecase.
byte[][]	split(int numRegions) Split an entire table.
byte[]	strToRow(String input)
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

xFF

static final byte xFF

See Also:

Constant Field Values

firstRowBytes

byte[] firstRowBytes

lastRowBytes

byte[] lastRowBytes

Constructor Detail

UniformSplit

public UniformSplit()

Method Detail

split

public byte[] split(byte[] start,
                    byte[] end)

Description copied from interface: RegionSplitter.SplitAlgorithm

Split a pre-existing region into 2 regions.

Specified by:

split in interface RegionSplitter.SplitAlgorithm

Parameters:

start - first row (inclusive)

end - last row (exclusive)

Returns:

the split row to use

split

public byte[][] split(int numRegions)

Description copied from interface: RegionSplitter.SplitAlgorithm

Split an entire table.

Specified by:

split in interface RegionSplitter.SplitAlgorithm

Parameters:

numRegions - number of regions to split the table into

Returns:

array of split keys for the initial regions of the table. The length of the returned array should be numRegions-1.

split

public byte[][] split(byte[] start,
                      byte[] end,
                      int numSplits,
                      boolean inclusive)

Description copied from interface: RegionSplitter.SplitAlgorithm

Some MapReduce jobs may want to run multiple mappers per region, this is intended for such usecase.

Specified by:

split in interface RegionSplitter.SplitAlgorithm

Parameters:

start - first row (inclusive)

end - last row (exclusive)

numSplits - number of splits to generate

inclusive - whether start and end are returned as split points

firstRow

public byte[] firstRow()

Description copied from interface: RegionSplitter.SplitAlgorithm

In HBase, the first row is represented by an empty byte array. This might cause problems with your split algorithm or row printing. All your APIs will be passed firstRow() instead of empty array.

Specified by:

firstRow in interface RegionSplitter.SplitAlgorithm

Returns:

your representation of your first row

lastRow

public byte[] lastRow()

Description copied from interface: RegionSplitter.SplitAlgorithm

In HBase, the last row is represented by an empty byte array. This might cause problems with your split algorithm or row printing. All your APIs will be passed firstRow() instead of empty array.

Specified by:

lastRow in interface RegionSplitter.SplitAlgorithm

Returns:

your representation of your last row

setFirstRow

public void setFirstRow(String userInput)

Description copied from interface: RegionSplitter.SplitAlgorithm

In HBase, the last row is represented by an empty byte array. Set this value to help the split code understand how to evenly divide the first region.

Specified by:

setFirstRow in interface RegionSplitter.SplitAlgorithm

Parameters:

userInput - raw user input (may throw RuntimeException on parse failure)

setLastRow

public void setLastRow(String userInput)

Description copied from interface: RegionSplitter.SplitAlgorithm

In HBase, the last row is represented by an empty byte array. Set this value to help the split code understand how to evenly divide the last region. Note that this last row is inclusive for all rows sharing the same prefix.

Specified by:

setLastRow in interface RegionSplitter.SplitAlgorithm

Parameters:

userInput - raw user input (may throw RuntimeException on parse failure)

setFirstRow

public void setFirstRow(byte[] userInput)

Description copied from interface: RegionSplitter.SplitAlgorithm

Set the first row

Specified by:

setFirstRow in interface RegionSplitter.SplitAlgorithm

Parameters:

userInput - byte array of the row key.

setLastRow

public void setLastRow(byte[] userInput)

Description copied from interface: RegionSplitter.SplitAlgorithm

Set the last row

Specified by:

setLastRow in interface RegionSplitter.SplitAlgorithm

Parameters:

userInput - byte array of the row key.

strToRow

public byte[] strToRow(String input)

Specified by:

strToRow in interface RegionSplitter.SplitAlgorithm

Parameters:

input - user or file input for row

Returns:

byte array representation of this row for HBase

rowToStr

public String rowToStr(byte[] row)

Specified by:

rowToStr in interface RegionSplitter.SplitAlgorithm

Parameters:

row - byte array representing a row in HBase

Returns:

String to use for debug & file printing

separator

public String separator()

Specified by:

separator in interface RegionSplitter.SplitAlgorithm

Returns:

the separator character to use when storing / printing the row

toString

public String toString()

Overrides:

toString in class Object