StatisticsImpl (Apache Derby V10.14 Internals)

java.lang.Object
- org.apache.derby.catalog.types.StatisticsImpl

All Implemented Interfaces:

java.io.Externalizable, java.io.Serializable, Statistics, Formatable, TypedFormat
```
public class StatisticsImpl
extends java.lang.Object
implements Statistics, Formatable
```
See Also:

Serialized Form

Field Summary

Fields
Modifier and Type Field Description

private long numRows

private long numUnique

Fields
Modifier and Type	Field	Description
`private long`	`numRows`
`private long`	`numUnique`

Constructor Summary

Constructors
Constructor	Description
`StatisticsImpl()`	Zero argument constructor for Formatable Interface
`StatisticsImpl(long numRows, long numUnique)`	Constructor for StatisticsImpl.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`long`	`getRowEstimate()`	Returns the estimated number of rows in the index.
`int`	`getTypeFormatId()`	Get a universally unique identifier for the type of this object.
`void`	`readExternal(java.io.ObjectInput in)`
`double`	`selectivity(java.lang.Object[] predicates)`
`java.lang.String`	`toString()`
`void`	`writeExternal(java.io.ObjectOutput out)`	Write this object to a stream of stored objects.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - numRows
```
private long numRows
```
  - numUnique
```
private long numUnique
```
- Constructor Detail
  - StatisticsImpl
```
public StatisticsImpl(long numRows,
                      long numUnique)
```
    Constructor for StatisticsImpl.
    
    Parameters:
    
    numRows - number of rows in the conglomerate for which this statistic is being created.
    
    numUnique - number of unique values in the key for which this statistic is being created.
  - StatisticsImpl
```
public StatisticsImpl()
```
    Zero argument constructor for Formatable Interface
- Method Detail
  - getRowEstimate
```
public long getRowEstimate()
```
    Returns the estimated number of rows in the index.
    
    Specified by:
    
    getRowEstimate in interface Statistics
    
    Returns:
    
    Number of rows.
  - selectivity
```
public double selectivity(java.lang.Object[] predicates)
```
    Specified by:
    
    selectivity in interface Statistics
    
    Returns:
    
    the selectivity for a set of predicates.
    
    See Also:
    
    Statistics.selectivity(java.lang.Object[])
  - readExternal
```
public void readExternal(java.io.ObjectInput in)
                  throws java.io.IOException,
                         java.lang.ClassNotFoundException
```
    Specified by:
    
    readExternal in interface java.io.Externalizable
    
    Throws:
    
    java.io.IOException
    
    java.lang.ClassNotFoundException
    
    See Also:
    
    Externalizable.readExternal(java.io.ObjectInput)
  - writeExternal
```
public void writeExternal(java.io.ObjectOutput out)
                   throws java.io.IOException
```
    Write this object to a stream of stored objects.
    
    Specified by:
    
    writeExternal in interface java.io.Externalizable
    
    Parameters:
    
    out - write bytes here.
    
    Throws:
    
    java.io.IOException - thrown on error
  - getTypeFormatId
```
public int getTypeFormatId()
```
    Description copied from interface: TypedFormat
    
    Get a universally unique identifier for the type of this object.
    
    Specified by:
    
    getTypeFormatId in interface TypedFormat
    
    Returns:
    
    the format id which corresponds to this class.
  - toString
```
public java.lang.String toString()
```
    Overrides:
    
    toString in class java.lang.Object
    
    See Also:
    
    Object.toString()

Class StatisticsImpl

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

numRows

numUnique

Constructor Detail

StatisticsImpl

StatisticsImpl

Method Detail

getRowEstimate

selectivity

readExternal

writeExternal

getTypeFormatId

toString