Package org.apache.druid.query.aggregation

Class NullableNumericAggregatorFactory<T extends BaseNullableColumnValueSelector>

java.lang.Object

org.apache.druid.query.aggregation.AggregatorFactory

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

All Implemented Interfaces:

Cacheable

Direct Known Subclasses:

SimpleDoubleAggregatorFactory, SimpleFloatAggregatorFactory, SimpleLongAggregatorFactory

public abstract class NullableNumericAggregatorFactory<T extends BaseNullableColumnValueSelector>
extends AggregatorFactory

Abstract superclass for null-aware numeric aggregators. Includes functionality to wrap Aggregator, BufferAggregator, VectorAggregator, and AggregateCombiner to support nullable aggregations. The result of this aggregator will be null if all the values to be aggregated are null values, or if no values are aggregated at all. If any of the values are non-null, the result will be the aggregated value of the non-null values. Aggregators that use BaseObjectColumnValueSelector.getObject() must override useGetObject(ColumnSelectorFactory). Otherwise, the logic in this class is not correct for non-numeric selectors.

See Also:

• for why this only works in the numeric case

Constructor Summary

Constructors

Constructor	Description
NullableNumericAggregatorFactory()

Method Summary

Modifier and Type	Method	Description
final Aggregator	factorize(ColumnSelectorFactory columnSelectorFactory)
protected abstract Aggregator	factorize(ColumnSelectorFactory columnSelectorFactory, T selector)	Creates an Aggregator to aggregate values from several rows, by using the provided selector.
final BufferAggregator	factorizeBuffered(ColumnSelectorFactory columnSelectorFactory)
protected abstract BufferAggregator	factorizeBuffered(ColumnSelectorFactory columnSelectorFactory, T selector)	Creates an BufferAggregator to aggregate values from several rows into a ByteBuffer.
final VectorAggregator	factorizeVector(VectorColumnSelectorFactory columnSelectorFactory)	Create a VectorAggregator based on the provided column selector factory.
protected VectorAggregator	factorizeVector(VectorColumnSelectorFactory columnSelectorFactory, VectorValueSelector selector)	Creates a VectorAggregator to aggregate values from several rows into a ByteBuffer.
boolean	forceNotNullable()	If true, this aggregator will not check for null inputs, instead directly delegating to the underlying aggregator.
final int	getMaxIntermediateSizeWithNulls()	Returns the maximum size that this aggregator will require in bytes for intermediate storage of results.
ColumnType	getResultType()	Get the ColumnType for the final form of this aggregator, i.e.
final AggregateCombiner	makeNullableAggregateCombiner()	Creates an AggregateCombiner which supports nullability.
protected abstract T	selector(ColumnSelectorFactory columnSelectorFactory)	Creates a ColumnValueSelector for the aggregated column.
protected boolean	useGetObject(ColumnSelectorFactory columnSelectorFactory)	Returns whether the selector created by selector(ColumnSelectorFactory) for the given ColumnSelectorFactory prefers BaseObjectColumnValueSelector.getObject().
protected VectorValueSelector	vectorSelector(VectorColumnSelectorFactory columnSelectorFactory)	Creates a VectorValueSelector for the aggregated column.

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

canVectorize, combine, deserialize, factorizeWithSize, finalizeComputation, getCombiningFactory, getComparator, getComplexTypeName, getFinalizedType, getIntermediateType, getMaxIntermediateSize, getMergingFactory, getName, getRequiredColumns, getType, guessAggregatorHeapFootprint, makeAggregateCombiner, mergeAggregators, optimizeForSegment, requiredFields, substituteCombiningFactory, withName

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 Details

NullableNumericAggregatorFactory

public NullableNumericAggregatorFactory()

Method Details

forceNotNullable

public boolean forceNotNullable()

If true, this aggregator will not check for null inputs, instead directly delegating to the underlying aggregator. Currently, this is only used by CountAggregatorFactory.getCombiningFactory(). This isn't entirely safe, as some selectors might throw an exception when attempting to retrieve a primitive value from `null`.

factorize

public final Aggregator factorize(ColumnSelectorFactory columnSelectorFactory)

Specified by:

factorize in class AggregatorFactory

factorizeBuffered

public final BufferAggregator factorizeBuffered(ColumnSelectorFactory columnSelectorFactory)

Specified by:

factorizeBuffered in class AggregatorFactory

factorizeVector

public final VectorAggregator factorizeVector(VectorColumnSelectorFactory columnSelectorFactory)

Description copied from class: AggregatorFactory

Create a VectorAggregator based on the provided column selector factory. Will throw an exception if this aggregation class does not support vectorization: check "canVectorize" first.

Overrides:

factorizeVector 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 NullableNumericAggregatorFactory instead of overriding this method. Default implementation calls AggregatorFactory.makeAggregateCombiner() for backwards compatibility.

Overrides:

makeNullableAggregateCombiner in class AggregatorFactory

See Also:

• AggregateCombiner
• NullableNumericAggregatorFactory

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 NullableNumericAggregatorFactory 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 columnSelectorFactory)

Creates a ColumnValueSelector for the aggregated column.

See Also:

• ColumnValueSelector

useGetObject

protected boolean useGetObject(ColumnSelectorFactory columnSelectorFactory)

Returns whether the selector created by selector(ColumnSelectorFactory) for the given ColumnSelectorFactory prefers BaseObjectColumnValueSelector.getObject(). For backwards compatibilty with older extensions, this is a non-abstract method.

vectorSelector

protected VectorValueSelector vectorSelector(VectorColumnSelectorFactory columnSelectorFactory)

Creates a VectorValueSelector for the aggregated column.

See Also:

• VectorValueSelector

factorize

protected abstract Aggregator factorize(ColumnSelectorFactory columnSelectorFactory,
 T selector)

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

Parameters:

columnSelectorFactory - metricFactory

selector - ColumnValueSelector for the column to aggregate.

See Also:

• Aggregator

factorizeBuffered

protected abstract BufferAggregator factorizeBuffered(ColumnSelectorFactory columnSelectorFactory,
 T selector)

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

Parameters:

columnSelectorFactory - columnSelectorFactory in case any other columns are needed.

selector - ColumnValueSelector for the column to aggregate.

See Also:

• BufferAggregator

factorizeVector

protected VectorAggregator factorizeVector(VectorColumnSelectorFactory columnSelectorFactory,
 VectorValueSelector selector)

Creates a VectorAggregator to aggregate values from several rows into a ByteBuffer.

Parameters:

columnSelectorFactory - columnSelectorFactory in case any other columns are needed.

selector - VectorValueSelector for the column to aggregate.

See Also:

• BufferAggregator

getResultType

public ColumnType getResultType()

Description copied from class: AggregatorFactory

Get the ColumnType for the final form of this aggregator, i.e. the type of the value returned by AggregatorFactory.finalizeComputation(java.lang.Object). This may be the same as or different than the types expected in AggregatorFactory.deserialize(java.lang.Object) and AggregatorFactory.combine(java.lang.Object, java.lang.Object). Refer to the ColumnType javadocs for details on the implications of choosing a type.

Overrides:

getResultType in class AggregatorFactory