Package org.apache.druid.query.aggregation

Class DelegatingAggregator

java.lang.Object

org.apache.druid.query.aggregation.DelegatingAggregator

All Implemented Interfaces:

Closeable, AutoCloseable, Aggregator

Direct Known Subclasses:

StringColumnDoubleAggregatorWrapper, StringColumnFloatAggregatorWrapper, StringColumnLongAggregatorWrapper

public abstract class DelegatingAggregator
extends Object
implements Aggregator

An Aggregator that delegates everything. It is used by Aggregator wrappers e.g. StringColumnDoubleAggregatorWrapper that modify some behavior of a delegate.

Field Summary

Fields

Modifier and Type	Field	Description
protected Aggregator	delegate

Constructor Summary

Constructors

Constructor	Description
DelegatingAggregator()

Method Summary

Modifier and Type	Method	Description
void	aggregate()	Performs aggregation.
void	close()
Object	get()
double	getDouble()	The default implementation casts Aggregator.getFloat() to double.
float	getFloat()
long	getLong()
boolean	isNull()	returns true if aggregator's output type is primitive long/double/float and aggregated value is null, but when aggregated output type is Object, this method always returns false, and users are advised to check nullability for the object returned by Aggregator.get() method.

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.query.aggregation.Aggregator

aggregateWithSize

Field Detail

delegate

protected Aggregator delegate

Constructor Detail

DelegatingAggregator

public DelegatingAggregator()

Method Detail

aggregate

public void aggregate()

Description copied from interface: Aggregator

Performs aggregation.

Specified by:

aggregate in interface Aggregator

get

@Nullable
public Object get()

Specified by:

get in interface Aggregator

getFloat

public float getFloat()

Specified by:

getFloat in interface Aggregator

getLong

public long getLong()

Specified by:

getLong in interface Aggregator

getDouble

public double getDouble()

Description copied from interface: Aggregator

The default implementation casts Aggregator.getFloat() to double. This default method is added to enable smooth backward compatibility, please re-implement it if your aggregators work with numeric double columns.

Specified by:

getDouble in interface Aggregator

isNull

public boolean isNull()

Description copied from interface: Aggregator

returns true if aggregator's output type is primitive long/double/float and aggregated value is null, but when aggregated output type is Object, this method always returns false, and users are advised to check nullability for the object returned by Aggregator.get() method. The default implementation always return false to enable smooth backward compatibility, re-implement if your aggregator is nullable.

Specified by:

isNull in interface Aggregator

close

public void close()

Specified by:

close in interface Aggregator

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable