Statistics (Apache Parquet Column 1.8.1 API)

java.lang.Object
- org.apache.parquet.column.statistics.Statistics<T>

Direct Known Subclasses:

BinaryStatistics, BooleanStatistics, DoubleStatistics, FloatStatistics, IntStatistics, LongStatistics
```
public abstract class Statistics<T extends Comparable<T>>
extends Object
```
Statistics class to keep track of statistics in parquet pages and column chunks

Author:

Katya Gonina

Constructor Summary

Constructors
Constructor and Description

Statistics()

Constructors
Constructor and Description
`Statistics()`

Method Summary

Methods
Modifier and Type	Method and Description
`boolean`	`equals(Object other)` Equality comparison method to compare two statistics objects.
`abstract T`	`genericGetMax()`
`abstract T`	`genericGetMin()`
`abstract byte[]`	`getMaxBytes()` Abstract method to return the max value as a byte array
`abstract byte[]`	`getMinBytes()` Abstract method to return the min value as a byte array
`long`	`getNumNulls()` Returns the null count
`static Statistics`	`getStatsBasedOnType(PrimitiveType.PrimitiveTypeName type)` Returns the typed statistics object based on the passed type parameter
`int`	`hashCode()` Hash code for the statistics object
`boolean`	`hasNonNullValue()` Returns whether there have been non-null values added to this statistics
`void`	`incrementNumNulls()` Increments the null count by one
`void`	`incrementNumNulls(long increment)` Increments the null count by the parameter value
`boolean`	`isEmpty()` Returns a boolean specifying if the Statistics object is empty, i.e does not contain valid statistics for the page/column yet
`protected void`	`markAsNotEmpty()` Sets the page/column as having a valid non-null value kind of misnomer here
`void`	`mergeStatistics(Statistics stats)` Method to merge this statistics object with the object passed as parameter.
`protected abstract void`	`mergeStatisticsMinMax(Statistics stats)` Abstract method to merge this statistics min and max with the values of the parameter object.
`abstract void`	`setMinMaxFromBytes(byte[] minBytes, byte[] maxBytes)` Abstract method to set min and max values from byte arrays.
`void`	`setNumNulls(long nulls)` Sets the number of nulls to the parameter value
`abstract String`	`toString()` toString() to display min, max, num_nulls in a string
`void`	`updateStats(Binary value)` updates statistics min and max using the passed value
`void`	`updateStats(boolean value)` updates statistics min and max using the passed value
`void`	`updateStats(double value)` updates statistics min and max using the passed value
`void`	`updateStats(float value)` updates statistics min and max using the passed value
`void`	`updateStats(int value)` updates statistics min and max using the passed value
`void`	`updateStats(long value)` updates statistics min and max using the passed value

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

- Constructor Detail
  - Statistics
```
public Statistics()
```
- Method Detail
  - getStatsBasedOnType
```
public static Statistics getStatsBasedOnType(PrimitiveType.PrimitiveTypeName type)
```
    Returns the typed statistics object based on the passed type parameter
    
    Parameters:
    type - PrimitiveTypeName type of the column
    
    Returns:
    instance of a typed statistics class
  - updateStats
```
public void updateStats(int value)
```
    updates statistics min and max using the passed value
    
    Parameters:
    value - value to use to update min and max
  - updateStats
```
public void updateStats(long value)
```
    updates statistics min and max using the passed value
    
    Parameters:
    value - value to use to update min and max
  - updateStats
```
public void updateStats(float value)
```
    updates statistics min and max using the passed value
    
    Parameters:
    value - value to use to update min and max
  - updateStats
```
public void updateStats(double value)
```
    updates statistics min and max using the passed value
    
    Parameters:
    value - value to use to update min and max
  - updateStats
```
public void updateStats(boolean value)
```
    updates statistics min and max using the passed value
    
    Parameters:
    value - value to use to update min and max
  - updateStats
```
public void updateStats(Binary value)
```
    updates statistics min and max using the passed value
    
    Parameters:
    value - value to use to update min and max
  - equals
```
public boolean equals(Object other)
```
    Equality comparison method to compare two statistics objects.
    
    Overrides:
    
    equals in class Object
    
    Parameters:
    other - Object to compare against
    
    Returns:
    true if objects are equal, false otherwise
  - hashCode
```
public int hashCode()
```
    Hash code for the statistics object
    
    Overrides:
    
    hashCode in class Object
    
    Returns:
    hash code int
  - mergeStatistics
```
public void mergeStatistics(Statistics stats)
```
    Method to merge this statistics object with the object passed as parameter. Merging keeps the smallest of min values, largest of max values and combines the number of null counts.
    
    Parameters:
    stats - Statistics object to merge with
  - mergeStatisticsMinMax
```
protected abstract void mergeStatisticsMinMax(Statistics stats)
```
    Abstract method to merge this statistics min and max with the values of the parameter object. Does not do any checks, only called internally.
    
    Parameters:
    stats - Statistics object to merge with
  - setMinMaxFromBytes
```
public abstract void setMinMaxFromBytes(byte[] minBytes,
                      byte[] maxBytes)
```
    Abstract method to set min and max values from byte arrays.
    
    Parameters:
    minBytes - byte array to set the min value to
    maxBytes - byte array to set the max value to
  - genericGetMin
```
public abstract T genericGetMin()
```
  - genericGetMax
```
public abstract T genericGetMax()
```
  - getMaxBytes
```
public abstract byte[] getMaxBytes()
```
    Abstract method to return the max value as a byte array
    
    Returns:
    byte array corresponding to the max value
  - getMinBytes
```
public abstract byte[] getMinBytes()
```
    Abstract method to return the min value as a byte array
    
    Returns:
    byte array corresponding to the min value
  - toString
```
public abstract String toString()
```
    toString() to display min, max, num_nulls in a string
    
    Overrides:
    
    toString in class Object
  - incrementNumNulls
```
public void incrementNumNulls()
```
    Increments the null count by one
  - incrementNumNulls
```
public void incrementNumNulls(long increment)
```
    Increments the null count by the parameter value
    
    Parameters:
    increment - value to increment the null count by
  - getNumNulls
```
public long getNumNulls()
```
    Returns the null count
    
    Returns:
    null count
  - setNumNulls
```
public void setNumNulls(long nulls)
```
    Sets the number of nulls to the parameter value
    
    Parameters:
    nulls - null count to set the count to
  - isEmpty
```
public boolean isEmpty()
```
    Returns a boolean specifying if the Statistics object is empty, i.e does not contain valid statistics for the page/column yet
    
    Returns:
    true if object is empty, false otherwise
  - hasNonNullValue
```
public boolean hasNonNullValue()
```
    Returns whether there have been non-null values added to this statistics
  - markAsNotEmpty
```
protected void markAsNotEmpty()
```
    Sets the page/column as having a valid non-null value kind of misnomer here

Class Statistics<T extends Comparable<T>>

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Statistics

Method Detail

getStatsBasedOnType

updateStats

updateStats

updateStats

updateStats

updateStats

updateStats

equals

hashCode

mergeStatistics

mergeStatisticsMinMax

setMinMaxFromBytes

genericGetMin

genericGetMax

getMaxBytes

getMinBytes

toString

incrementNumNulls

incrementNumNulls

getNumNulls

setNumNulls

isEmpty

hasNonNullValue

markAsNotEmpty