org.apache.druid.query.aggregation

Class NullableAggregatorFactory<T extends BaseNullableColumnValueSelector>

java.lang.Object

org.apache.druid.query.aggregation.AggregatorFactory

org.apache.druid.query.aggregation.NullableAggregatorFactory<T>

All Implemented Interfaces:

Cacheable

Direct Known Subclasses:

DoubleFirstAggregatorFactory, DoubleLastAggregatorFactory, FloatFirstAggregatorFactory, FloatLastAggregatorFactory, LongFirstAggregatorFactory, LongLastAggregatorFactory, SimpleDoubleAggregatorFactory, SimpleFloatAggregatorFactory, SimpleLongAggregatorFactory, StringFirstAggregatorFactory, StringLastAggregatorFactory

public abstract class NullableAggregatorFactory<T extends BaseNullableColumnValueSelector>
extends AggregatorFactory

Abstract class with functionality to wrap Aggregator, BufferAggregator and AggregateCombiner to support nullable aggregations for SQL compatibility. Implementations of AggregatorFactory which need to Support Nullable Aggregations are encouraged to extend this class.

Constructor Summary

Constructors

Constructor and Description
NullableAggregatorFactory()

Method Summary

Modifier and Type	Method and Description
Aggregator	factorize(ColumnSelectorFactory metricFactory)
protected abstract Aggregator	factorize(ColumnSelectorFactory metricFactory, T selector) Creates an Aggregator to aggregate values from several rows, by using the provided selector.
BufferAggregator	factorizeBuffered(ColumnSelectorFactory metricFactory)
protected abstract BufferAggregator	factorizeBuffered(ColumnSelectorFactory metricFactory, T selector) Creates an BufferAggregator to aggregate values from several rows into a ByteBuffer.
int	getMaxIntermediateSizeWithNulls() Returns the maximum size that this aggregator will require in bytes for intermediate storage of results.
AggregateCombiner	makeNullableAggregateCombiner() Creates an AggregateCombiner which supports nullability.
protected abstract T	selector(ColumnSelectorFactory metricFactory) Creates a ColumnValueSelector for the aggregated column.

Methods inherited from class org.apache.druid.query.aggregation.AggregatorFactory

combine, deserialize, finalizeComputation, getCombiningFactory, getComparator, getMaxIntermediateSize, getMergingFactory, getName, getRequiredColumns, getTypeName, makeAggregateCombiner, mergeAggregators, optimizeForSegment, requiredFields

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.druid.java.util.common.Cacheable

getCacheKey

Constructor Detail

NullableAggregatorFactory

public NullableAggregatorFactory()

Method Detail

factorize

public final Aggregator factorize(ColumnSelectorFactory metricFactory)

Specified by:

factorize in class AggregatorFactory

factorizeBuffered

public final BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)

Specified by:

factorizeBuffered in class AggregatorFactory

makeNullableAggregateCombiner

public final AggregateCombiner makeNullableAggregateCombiner()

Description copied from class: AggregatorFactory

Creates an AggregateCombiner which supports nullability. Implementations of AggregatorFactory which need to Support Nullable Aggregations are encouraged to extend NullableAggregatorFactory instead of overriding this method. Default implementation calls AggregatorFactory.makeAggregateCombiner() for backwards compatibility.

Overrides:

makeNullableAggregateCombiner in class AggregatorFactory

See Also:

AggregateCombiner, NullableAggregatorFactory

getMaxIntermediateSizeWithNulls

public final int getMaxIntermediateSizeWithNulls()

Description copied from class: AggregatorFactory

Returns the maximum size that this aggregator will require in bytes for intermediate storage of results. Implementations of AggregatorFactory which need to Support Nullable Aggregations are encouraged to extend NullableAggregatorFactory instead of overriding this method. Default implementation calls AggregatorFactory.makeAggregateCombiner() for backwards compatibility.

Overrides:

getMaxIntermediateSizeWithNulls in class AggregatorFactory

Returns:

the maximum number of bytes that an aggregator of this type will require for intermediate result storage.

selector

protected abstract T selector(ColumnSelectorFactory metricFactory)

Creates a ColumnValueSelector for the aggregated column.

See Also:

ColumnValueSelector

factorize

protected abstract Aggregator factorize(ColumnSelectorFactory metricFactory,
                                        T selector)

Creates an Aggregator to aggregate values from several rows, by using the provided selector.

Parameters:

metricFactory - metricFactory

selector - ColumnValueSelector for the column to aggregate.

See Also:

Aggregator

factorizeBuffered

protected abstract BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory,
                                                      T selector)

Creates an BufferAggregator to aggregate values from several rows into a ByteBuffer.

Parameters:

metricFactory - metricFactory

selector - ColumnValueSelector for the column to aggregate.

See Also:

BufferAggregator