org.apache.flink.table.runtime.functions.aggregate

Class CollectAggFunction<T>

java.lang.Object

org.apache.flink.table.functions.UserDefinedFunction

org.apache.flink.table.functions.ImperativeAggregateFunction<T,ACC>

org.apache.flink.table.functions.AggregateFunction<T,ACC>

org.apache.flink.table.runtime.functions.aggregate.BuiltInAggregateFunction<MapData,CollectAggFunction.CollectAccumulator<T>>

org.apache.flink.table.runtime.functions.aggregate.CollectAggFunction<T>

All Implemented Interfaces:

Serializable, FunctionDefinition

@Internal
public final class CollectAggFunction<T>
extends BuiltInAggregateFunction<MapData,CollectAggFunction.CollectAccumulator<T>>

Built-in COLLECT aggregate function.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	CollectAggFunction.CollectAccumulator<T> Accumulator for COLLECT.

Constructor Summary

Constructors

Constructor and Description
CollectAggFunction(LogicalType elementType)

Method Summary

Modifier and Type	Method and Description
void	accumulate(CollectAggFunction.CollectAccumulator<T> accumulator, T value)
CollectAggFunction.CollectAccumulator<T>	createAccumulator() Creates and initializes the accumulator for this ImperativeAggregateFunction.
DataType	getAccumulatorDataType()
List<DataType>	getArgumentDataTypes()
DataType	getOutputDataType()
MapData	getValue(CollectAggFunction.CollectAccumulator<T> accumulator) Called every time when an aggregation result should be materialized.
void	merge(CollectAggFunction.CollectAccumulator<T> accumulator, Iterable<CollectAggFunction.CollectAccumulator<T>> others)
void	resetAccumulator(CollectAggFunction.CollectAccumulator<T> accumulator)
void	retract(CollectAggFunction.CollectAccumulator<T> accumulator, T value)

Methods inherited from class org.apache.flink.table.runtime.functions.aggregate.BuiltInAggregateFunction

getRequirements, getTypeInference, isDeterministic

Methods inherited from class org.apache.flink.table.functions.AggregateFunction

getKind

Methods inherited from class org.apache.flink.table.functions.ImperativeAggregateFunction

getAccumulatorType, getResultType

Methods inherited from class org.apache.flink.table.functions.UserDefinedFunction

close, functionIdentifier, open, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

CollectAggFunction

public CollectAggFunction(LogicalType elementType)

Method Detail

getArgumentDataTypes

public List<DataType> getArgumentDataTypes()

Overrides:

getArgumentDataTypes in class BuiltInAggregateFunction<MapData,CollectAggFunction.CollectAccumulator<T>>

getAccumulatorDataType

public DataType getAccumulatorDataType()

Overrides:

getAccumulatorDataType in class BuiltInAggregateFunction<MapData,CollectAggFunction.CollectAccumulator<T>>

getOutputDataType

public DataType getOutputDataType()

Overrides:

getOutputDataType in class BuiltInAggregateFunction<MapData,CollectAggFunction.CollectAccumulator<T>>

createAccumulator

public CollectAggFunction.CollectAccumulator<T> createAccumulator()

Description copied from class: ImperativeAggregateFunction

Creates and initializes the accumulator for this ImperativeAggregateFunction.

The accumulator is an intermediate data structure that stores the aggregated values until a final aggregation result is computed.

Specified by:

createAccumulator in class ImperativeAggregateFunction<MapData,CollectAggFunction.CollectAccumulator<T>>

Returns:

the accumulator with the initial value

resetAccumulator

public void resetAccumulator(CollectAggFunction.CollectAccumulator<T> accumulator)

accumulate

public void accumulate(CollectAggFunction.CollectAccumulator<T> accumulator,
                       T value)
                throws Exception

Throws:

Exception

retract

public void retract(CollectAggFunction.CollectAccumulator<T> accumulator,
                    T value)
             throws Exception

Throws:

Exception

merge

public void merge(CollectAggFunction.CollectAccumulator<T> accumulator,
                  Iterable<CollectAggFunction.CollectAccumulator<T>> others)
           throws Exception

Throws:

Exception

getValue

public MapData getValue(CollectAggFunction.CollectAccumulator<T> accumulator)

Description copied from class: AggregateFunction

Called every time when an aggregation result should be materialized. The returned value could be either an early and incomplete result (periodically emitted as data arrives) or the final result of the aggregation.

Specified by:

getValue in class AggregateFunction<MapData,CollectAggFunction.CollectAccumulator<T>>

Parameters:

accumulator - the accumulator which contains the current intermediate results

Returns:

the aggregation result