org.apache.hadoop.zebra.io
Class KeyDistribution

java.lang.Object
  org.apache.hadoop.zebra.io.KeyDistribution

public class KeyDistribution
extends Object

Class used to convey the information of how on-disk data are distributed among key-partitioned buckets. This class is used by the MapReduce layer to calculate intelligent splits.

Method Summary

BlockDistribution	getBlockDistribution(RawComparable key)
RawComparable[]	getKeys() Get the list of sampling keys
long	getMinStepSize() Get the minimum split step size from all tables in union
long	length() Get the total unique bytes contained in the key-partitioned buckets.
static KeyDistribution	merge(KeyDistribution[] sourceKeys) Merge the key samples Algorithm: select the smallest key from all clean source ranges and ranges subsequent to respective dirty ranges.
int	resize(BlockDistribution lastBd)
int	size() Get the size of the key sampling.

Methods inherited from class java.lang.Object

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

Method Detail

length

public long length()

Get the total unique bytes contained in the key-partitioned buckets.

Returns:

The total number of bytes contained in the key-partitioned buckets.

size

public int size()

Get the size of the key sampling.

Returns:

Number of key samples.

getMinStepSize

public long getMinStepSize()

Get the minimum split step size from all tables in union

getKeys

public RawComparable[] getKeys()

Get the list of sampling keys

Returns:

A list of sampling keys

getBlockDistribution

public BlockDistribution getBlockDistribution(RawComparable key)

merge

public static KeyDistribution merge(KeyDistribution[] sourceKeys)
                             throws IOException

Merge the key samples Algorithm: select the smallest key from all clean source ranges and ranges subsequent to respective dirty ranges. A dirty range is a range that has been partially needed by one or more of the previous final ranges.

Parameters:

sourceKeys - key samples to be merged

Returns:

the merged key samples

Throws:

IOException

resize

public int resize(BlockDistribution lastBd)