org.apache.druid.query.aggregation

Class DoubleMaxAggregatorFactory

java.lang.Object

org.apache.druid.query.aggregation.AggregatorFactory

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

org.apache.druid.query.aggregation.SimpleDoubleAggregatorFactory

org.apache.druid.query.aggregation.DoubleMaxAggregatorFactory

All Implemented Interfaces:

Cacheable

public class DoubleMaxAggregatorFactory
extends SimpleDoubleAggregatorFactory

Field Summary

Fields inherited from class org.apache.druid.query.aggregation.SimpleDoubleAggregatorFactory

expression, fieldExpression, fieldName, macroTable, name, storeDoubleAsFloat

Constructor Summary

Constructors

Constructor and Description
DoubleMaxAggregatorFactory(String name, String fieldName)
DoubleMaxAggregatorFactory(String name, String fieldName, String expression, ExprMacroTable macroTable)

Method Summary

Modifier and Type	Method and Description
protected Aggregator	buildAggregator(BaseDoubleColumnValueSelector selector)
protected BufferAggregator	buildBufferAggregator(BaseDoubleColumnValueSelector selector)
Object	combine(Object lhs, Object rhs) A method that knows how to combine the outputs of Aggregator.get() produced via AggregatorFactory.factorize(org.apache.druid.segment.ColumnSelectorFactory) or BufferAggregator.get(java.nio.ByteBuffer, int) produced via AggregatorFactory.factorizeBuffered(org.apache.druid.segment.ColumnSelectorFactory).
protected VectorAggregator	factorizeVector(VectorColumnSelectorFactory columnSelectorFactory, VectorValueSelector selector) Creates a VectorAggregator to aggregate values from several rows into a ByteBuffer.
byte[]	getCacheKey() Get a byte array used as a cache key.
AggregatorFactory	getCombiningFactory() Returns an AggregatorFactory that can be used to combine the output of aggregators from this factory.
List<AggregatorFactory>	getRequiredColumns() Used by GroupByStrategyV1 when running nested groupBys, to "transfer" values from this aggreagtor to an incremental index that the outer query will run on.
AggregateCombiner	makeAggregateCombiner() Creates an AggregateCombiner to fold rollup aggregation results from serveral "rows" of different indexes during index merging.
protected double	nullValue()
String	toString()
AggregatorFactory	withName(String newName) Used in cases where we want to change the output name of the aggregator to something else.

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

canVectorize, deserialize, equals, factorize, factorizeBuffered, finalizeComputation, getComparator, getExpression, getFieldName, getIntermediateType, getMaxIntermediateSize, getMergingFactory, getName, hashCode, requiredFields, selector, vectorSelector

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

factorize, factorizeBuffered, factorizeVector, getMaxIntermediateSizeWithNulls, getResultType, makeNullableAggregateCombiner

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

factorizeWithSize, getComplexTypeName, getFinalizedType, getType, guessAggregatorHeapFootprint, mergeAggregators, optimizeForSegment

Methods inherited from class java.lang.Object

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

Constructor Detail

DoubleMaxAggregatorFactory

public DoubleMaxAggregatorFactory(String name,
                                  String fieldName,
                                  @Nullable
                                  String expression,
                                  ExprMacroTable macroTable)

DoubleMaxAggregatorFactory

public DoubleMaxAggregatorFactory(String name,
                                  String fieldName)

Method Detail

nullValue

protected double nullValue()

Specified by:

nullValue in class SimpleDoubleAggregatorFactory

buildAggregator

protected Aggregator buildAggregator(BaseDoubleColumnValueSelector selector)

Specified by:

buildAggregator in class SimpleDoubleAggregatorFactory

buildBufferAggregator

protected BufferAggregator buildBufferAggregator(BaseDoubleColumnValueSelector selector)

Specified by:

buildBufferAggregator in class SimpleDoubleAggregatorFactory

factorizeVector

protected VectorAggregator factorizeVector(VectorColumnSelectorFactory columnSelectorFactory,
                                           VectorValueSelector selector)

Description copied from class: NullableNumericAggregatorFactory

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

Overrides:

factorizeVector in class NullableNumericAggregatorFactory<ColumnValueSelector>

Parameters:

columnSelectorFactory - columnSelectorFactory in case any other columns are needed.

selector - VectorValueSelector for the column to aggregate.

See Also:

BufferAggregator

combine

@Nullable
public Object combine(@Nullable
                                Object lhs,
                                @Nullable
                                Object rhs)

Description copied from class: AggregatorFactory

A method that knows how to combine the outputs of Aggregator.get() produced via AggregatorFactory.factorize(org.apache.druid.segment.ColumnSelectorFactory) or BufferAggregator.get(java.nio.ByteBuffer, int) produced via AggregatorFactory.factorizeBuffered(org.apache.druid.segment.ColumnSelectorFactory). Note, even though this method is called "combine", this method's contract *does* allow for mutation of the input objects. Thus, any use of lhs or rhs after calling this method is highly discouraged.

Specified by:

combine in class AggregatorFactory

Parameters:

lhs - The left hand side of the combine

rhs - The right hand side of the combine

Returns:

an object representing the combination of lhs and rhs, this can be a new object or a mutation of the inputs

makeAggregateCombiner

public AggregateCombiner makeAggregateCombiner()

Description copied from class: AggregatorFactory

Creates an AggregateCombiner to fold rollup aggregation results from serveral "rows" of different indexes during index merging. AggregateCombiner implements the same logic as AggregatorFactory.combine(java.lang.Object, java.lang.Object), with the difference that it uses ColumnValueSelector and it's subinterfaces to get inputs and implements ColumnValueSelector to provide output.

Overrides:

makeAggregateCombiner in class AggregatorFactory

See Also:

AggregateCombiner, IndexMerger

getCombiningFactory

public AggregatorFactory getCombiningFactory()

Description copied from class: AggregatorFactory

Returns an AggregatorFactory that can be used to combine the output of aggregators from this factory. It is used when we know we have some values that were produced with this aggregator factory, and want to do some additional combining of them. This happens, for example, when merging query results from two different segments, or two different servers. For simple aggregators, the combining factory may be computed by simply creating a new factory that is the same as the current, except with its input column renamed to the same as the output column. For example, this aggregator: {"type": "longSum", "fieldName": "foo", "name": "bar"} Would become: {"type": "longSum", "fieldName": "bar", "name": "bar"} Sometimes, the type or other parameters of the combining aggregator will be different from the original aggregator. For example, the CountAggregatorFactory getCombiningFactory method will return a LongSumAggregatorFactory, because counts are combined by summing. No matter what, `foo.getCombiningFactory()` and `foo.getCombiningFactory().getCombiningFactory()` should return the same result.

Specified by:

getCombiningFactory in class AggregatorFactory

Returns:

a new Factory that can be used for operations on top of data output from the current factory.

getRequiredColumns

public List<AggregatorFactory> getRequiredColumns()

Description copied from class: AggregatorFactory

Used by GroupByStrategyV1 when running nested groupBys, to "transfer" values from this aggreagtor to an incremental index that the outer query will run on. This method only exists due to the design of GroupByStrategyV1, and should probably not be used for anything else. If you are here because you are looking for a way to get the input fields required by this aggregator, and thought "getRequiredColumns" sounded right, please use AggregatorFactory.requiredFields() instead.

Specified by:

getRequiredColumns in class AggregatorFactory

Returns:

AggregatorFactories that can be used to "transfer" values from this aggregator into an incremental index

See Also:

a similarly-named method that is perhaps the one you want instead.

withName

public AggregatorFactory withName(String newName)

Description copied from class: AggregatorFactory

Used in cases where we want to change the output name of the aggregator to something else. For eg: if we have a query `select a, sum(b) as total group by a from table` the aggregator returned from the native group by query is "a0" set in org.apache.druid.sql.calcite.rel.DruidQuery#computeAggregations. We can use withName("total") to set the output name of the aggregator to "total".

As all implementations of this interface method may not exist, callers of this method are advised to handle such a case.

Overrides:

withName in class AggregatorFactory

Parameters:

newName - newName of the output for aggregator factory

Returns:

AggregatorFactory with the output name set as the input param.

getCacheKey

public byte[] getCacheKey()

Description copied from interface: Cacheable

Get a byte array used as a cache key.

Returns:

a cache key

toString

public String toString()

Overrides:

toString in class Object