org.apache.drill.metastore.statistics

Class ColumnStatisticsKind<T>

java.lang.Object

org.apache.drill.metastore.statistics.BaseStatisticsKind<T>

org.apache.drill.metastore.statistics.ColumnStatisticsKind<T>

All Implemented Interfaces:

CollectableColumnStatisticsKind<T>, StatisticsKind<T>

public class ColumnStatisticsKind<T>
extends BaseStatisticsKind<T>
implements CollectableColumnStatisticsKind<T>

Implementation of CollectableColumnStatisticsKind which contain base column statistics kinds with implemented mergeStatistics() method.

Field Summary

Fields

Modifier and Type	Field and Description
static ColumnStatisticsKind<?>	AVG_WIDTH Column statistics kind which is the width of the specific column.
static ColumnStatisticsKind<Histogram>	HISTOGRAM Column statistics kind which is the histogram of the specific column.
static ColumnStatisticsKind<Object>	MAX_VALUE Column statistics kind which represents max value of the specific column.
static ColumnStatisticsKind<Object>	MIN_VALUE Column statistics kind which represents min value of the specific column.
static ColumnStatisticsKind<Double>	NDV Column statistics kind which represents number of distinct values for the specific column.
static ColumnStatisticsKind<Double>	NON_NULL_COUNT Column statistics kind which represents estimated number of non-null values for the specific column.
static ColumnStatisticsKind<Long>	NON_NULL_VALUES_COUNT Column statistics kind which represents exact number of non-null values for the specific column.
static ColumnStatisticsKind<Long>	NULLS_COUNT Column statistics kind which represents nulls count for the specific column.
static ColumnStatisticsKind<Double>	ROWCOUNT Column statistics kind which represents total row count for the specific column.

Fields inherited from class org.apache.drill.metastore.statistics.BaseStatisticsKind

exact, statisticKey

Method Summary

Modifier and Type	Method and Description
T	getFrom(ColumnStatistics<?> metadata) Returns value which corresponds to this statistic kind, obtained from specified BaseMetadata.
<V> V	getValueStatistic(ColumnStatistics<V> metadata)
T	mergeStatistics(List<? extends ColumnStatistics<?>> statistics) Returns column statistics value received by collecting specified ColumnStatistics.

Methods inherited from class org.apache.drill.metastore.statistics.BaseStatisticsKind

equals, getName, hashCode, isExact, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.drill.metastore.statistics.StatisticsKind

getName, isExact

Field Detail

NULLS_COUNT

public static final ColumnStatisticsKind<Long> NULLS_COUNT

Column statistics kind which represents nulls count for the specific column.

MIN_VALUE

public static final ColumnStatisticsKind<Object> MIN_VALUE

Column statistics kind which represents min value of the specific column.

MAX_VALUE

public static final ColumnStatisticsKind<Object> MAX_VALUE

Column statistics kind which represents max value of the specific column.

NON_NULL_VALUES_COUNT

public static final ColumnStatisticsKind<Long> NON_NULL_VALUES_COUNT

Column statistics kind which represents exact number of non-null values for the specific column.

NON_NULL_COUNT

public static final ColumnStatisticsKind<Double> NON_NULL_COUNT

Column statistics kind which represents estimated number of non-null values for the specific column.

ROWCOUNT

public static final ColumnStatisticsKind<Double> ROWCOUNT

Column statistics kind which represents total row count for the specific column.

NDV

public static final ColumnStatisticsKind<Double> NDV

Column statistics kind which represents number of distinct values for the specific column.

AVG_WIDTH

public static final ColumnStatisticsKind<?> AVG_WIDTH

Column statistics kind which is the width of the specific column.

HISTOGRAM

public static final ColumnStatisticsKind<Histogram> HISTOGRAM

Column statistics kind which is the histogram of the specific column.

Method Detail

getFrom

public T getFrom(ColumnStatistics<?> metadata)

Returns value which corresponds to this statistic kind, obtained from specified BaseMetadata.

Parameters:

metadata - the source of statistic value

Returns:

value which corresponds to this statistic kind

getValueStatistic

public <V> V getValueStatistic(ColumnStatistics<V> metadata)

mergeStatistics

public T mergeStatistics(List<? extends ColumnStatistics<?>> statistics)

Description copied from interface: CollectableColumnStatisticsKind

Returns column statistics value received by collecting specified ColumnStatistics.

Specified by:

mergeStatistics in interface CollectableColumnStatisticsKind<T>

Parameters:

statistics - list of ColumnStatistics instances to be collected

Returns:

column statistics value received by collecting specified ColumnStatistics