parquet.column.statistics

Class Statistics<T extends Comparable<T>>

java.lang.Object

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()

Method Summary

Methods

Modifier and Type	Method and Description
boolean	equals(Statistics stats) 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
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()
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, equals, 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(Statistics stats)

Equality comparison method to compare two statistics objects.

Parameters:

stats - Statistics 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

markAsNotEmpty

protected void markAsNotEmpty()