org.tikv.common.statistics

Class Bucket

java.lang.Object

org.tikv.common.statistics.Bucket

All Implemented Interfaces:

Comparable<Bucket>

public class Bucket
extends Object
implements Comparable<Bucket>

Bucket is histogram element.

Bucket bound is the smallest and greatest values stored in the bucket. The lower and upper bound are stored in bucket as lowerBound and upperBound.

A bucket count is the number of items stored in all previous buckets and the current bucket. Bucket counts are always in increasing order.

A bucket repeat is the number of repeats of the greatest bucket value, it can be used to find popular values.

Note that lowerBound and upperBound keys should be 'comparable objects', and these bounds are encoded as `binary` type in TiDB. Intuitively, you should also use Keys encoded as binary format to do comparison in row count estimation.

Field Summary

Fields

Modifier and Type	Field and Description
long	count

Constructor Summary

Constructors

Constructor and Description
Bucket(Key upperBound) used for binary search only
Bucket(long count, long repeats, Key lowerBound, Key upperBound)

Method Summary

Modifier and Type	Method and Description
int	compareTo(Bucket b)
long	getCount()
Key	getLowerBound()
long	getRepeats()
Key	getUpperBound()
void	setCount(long count)
void	setLowerBound(Key lowerBound)
void	setRepeats(long repeats)
void	setUpperBound(Key upperBound)
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

count

public long count

Constructor Detail

Bucket

public Bucket(long count,
              long repeats,
              Key lowerBound,
              Key upperBound)

Bucket

public Bucket(Key upperBound)

used for binary search only

Method Detail

compareTo

public int compareTo(Bucket b)

Specified by:

compareTo in interface Comparable<Bucket>

getCount

public long getCount()

setCount

public void setCount(long count)

getRepeats

public long getRepeats()

setRepeats

public void setRepeats(long repeats)

getLowerBound

public Key getLowerBound()

setLowerBound

public void setLowerBound(Key lowerBound)

getUpperBound

public Key getUpperBound()

setUpperBound

public void setUpperBound(Key upperBound)

toString

public String toString()

Overrides:

toString in class Object