io.druid.query.aggregation.cardinality

Class CardinalityAggregatorFactory

java.lang.Object

io.druid.query.aggregation.AggregatorFactory

io.druid.query.aggregation.cardinality.CardinalityAggregatorFactory

All Implemented Interfaces:

Cacheable

public class CardinalityAggregatorFactory
extends AggregatorFactory

Constructor Summary

Constructors

Constructor and Description
CardinalityAggregatorFactory(String name, List<DimensionSpec> fields, boolean byRow)
CardinalityAggregatorFactory(String name, List<String> fieldNames, List<DimensionSpec> fields, boolean byRow)

Method Summary

Modifier and Type	Method and Description
Object	combine(Object lhs, Object rhs) A method that knows how to combine the outputs of the getIntermediate() method from the Aggregators produced via factorize().
Object	deserialize(Object object) A method that knows how to "deserialize" the object from whatever form it might have been put into in order to transfer via JSON.
boolean	equals(Object o)
static Object	estimateCardinality(Object object)
Aggregator	factorize(ColumnSelectorFactory columnFactory)
BufferAggregator	factorizeBuffered(ColumnSelectorFactory columnFactory)
Object	finalizeComputation(Object object) "Finalizes" the computation of an object.
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.
Comparator	getComparator()
List<DimensionSpec>	getFields()
int	getMaxIntermediateSize() Returns the maximum size that this aggregator will require in bytes for intermediate storage of results.
AggregatorFactory	getMergingFactory(AggregatorFactory other) Returns an AggregatorFactory that can be used to merge the output of aggregators from this factory and other factory.
String	getName()
List<AggregatorFactory>	getRequiredColumns() Gets a list of all columns that this AggregatorFactory will scan
String	getTypeName()
int	hashCode()
boolean	isByRow()
List<String>	requiredFields()
String	toString()

Methods inherited from class io.druid.query.aggregation.AggregatorFactory

mergeAggregators

Methods inherited from class java.lang.Object

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

Constructor Detail

CardinalityAggregatorFactory

public CardinalityAggregatorFactory(String name,
                                    @Deprecated
                                    List<String> fieldNames,
                                    List<DimensionSpec> fields,
                                    boolean byRow)

CardinalityAggregatorFactory

public CardinalityAggregatorFactory(String name,
                                    List<DimensionSpec> fields,
                                    boolean byRow)

Method Detail

estimateCardinality

public static Object estimateCardinality(Object object)

factorize

public Aggregator factorize(ColumnSelectorFactory columnFactory)

Specified by:

factorize in class AggregatorFactory

factorizeBuffered

public BufferAggregator factorizeBuffered(ColumnSelectorFactory columnFactory)

Specified by:

factorizeBuffered in class AggregatorFactory

getComparator

public Comparator getComparator()

Specified by:

getComparator in class AggregatorFactory

combine

public Object combine(Object lhs,
                      Object rhs)

Description copied from class: AggregatorFactory

A method that knows how to combine the outputs of the getIntermediate() method from the Aggregators produced via factorize(). Note, even though this 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

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. This generally amounts to 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.

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.

getMergingFactory

public AggregatorFactory getMergingFactory(AggregatorFactory other)
                                    throws AggregatorFactoryNotMergeableException

Description copied from class: AggregatorFactory

Returns an AggregatorFactory that can be used to merge the output of aggregators from this factory and other factory. This method is relevant only for AggregatorFactory which can be used at ingestion time.

Overrides:

getMergingFactory in class AggregatorFactory

Returns:

a new Factory that can be used for merging the output of aggregators from this factory and other.

Throws:

AggregatorFactoryNotMergeableException

getRequiredColumns

public List<AggregatorFactory> getRequiredColumns()

Description copied from class: AggregatorFactory

Gets a list of all columns that this AggregatorFactory will scan

Specified by:

getRequiredColumns in class AggregatorFactory

Returns:

AggregatorFactories for the columns to scan of the parent AggregatorFactory

deserialize

public Object deserialize(Object object)

Description copied from class: AggregatorFactory

A method that knows how to "deserialize" the object from whatever form it might have been put into in order to transfer via JSON.

Specified by:

deserialize in class AggregatorFactory

Parameters:

object - the object to deserialize

Returns:

the deserialized object

finalizeComputation

public Object finalizeComputation(Object object)

Description copied from class: AggregatorFactory

"Finalizes" the computation of an object. Primarily useful for complex types that have a different mergeable intermediate format than their final resultant output.

Specified by:

finalizeComputation in class AggregatorFactory

Parameters:

object - the object to be finalized

Returns:

the finalized value that should be returned for the initial query

getName

public String getName()

Specified by:

getName in class AggregatorFactory

requiredFields

public List<String> requiredFields()

Specified by:

requiredFields in class AggregatorFactory

getFields

public List<DimensionSpec> getFields()

isByRow

public boolean isByRow()

getCacheKey

public byte[] getCacheKey()

Description copied from interface: Cacheable

Get a byte array used as a cache key.

Returns:

a cache key

getTypeName

public String getTypeName()

Specified by:

getTypeName in class AggregatorFactory

getMaxIntermediateSize

public int getMaxIntermediateSize()

Description copied from class: AggregatorFactory

Returns the maximum size that this aggregator will require in bytes for intermediate storage of results.

Specified by:

getMaxIntermediateSize in class AggregatorFactory

Returns:

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

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object