org.apache.hadoop.hbase.util

Class LossyCounting

java.lang.Object

org.apache.hadoop.hbase.util.LossyCounting

@InterfaceAudience.Public
public class LossyCounting
extends Object

LossyCounting utility, bounded data structure that maintains approximate high frequency elements in data stream. Bucket size is 1 / error rate. (Error rate is 0.02 by default) Lemma If element
does not appear in set, then is frequency is less than e * N (N is total element counts until now.) Based on paper: http://www.vldb.org/conf/2002/S10P03.pdf

Constructor Summary

Constructors

Constructor and Description
LossyCounting(double errorRate, String name)
LossyCounting(String name)

Method Summary

Modifier and Type	Method and Description
Set<String>	addByOne(String key)
boolean	contains(String key)
long	getBucketSize()
long	getCurrentTerm()
long	getDataSize()

Methods inherited from class java.lang.Object

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

Constructor Detail

LossyCounting

public LossyCounting(double errorRate,
                     String name)

LossyCounting

public LossyCounting(String name)

Method Detail

addByOne

public Set<String> addByOne(String key)

getBucketSize

public long getBucketSize()

getDataSize

public long getDataSize()

contains

public boolean contains(String key)

getCurrentTerm

public long getCurrentTerm()