Package org.apache.flink.table.toolbox

Class CountAggFunction

java.lang.Object

org.apache.flink.table.functions.UserDefinedFunction

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

org.apache.flink.table.functions.AggregateFunction<Long,CountAggFunction.CountAccumulator>

org.apache.flink.table.toolbox.CountAggFunction

All Implemented Interfaces:

Serializable, FunctionDefinition

public class CountAggFunction
extends AggregateFunction<Long,CountAggFunction.CountAccumulator>

Count agg aggregate.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	CountAggFunction.CountAccumulator	The initial accumulator for count aggregate function.

Constructor Summary

Constructors

Constructor	Description
CountAggFunction()

Method Summary

Modifier and Type	Method	Description
void	accumulate(CountAggFunction.CountAccumulator acc)
void	accumulate(CountAggFunction.CountAccumulator acc, Long value)
CountAggFunction.CountAccumulator	createAccumulator()	Creates and initializes the accumulator for this ImperativeAggregateFunction.
Long	getValue(CountAggFunction.CountAccumulator acc)	Called every time when an aggregation result should be materialized.
void	merge(CountAggFunction.CountAccumulator acc, Iterable<CountAggFunction.CountAccumulator> its)
void	retract(CountAggFunction.CountAccumulator acc)
void	retract(CountAggFunction.CountAccumulator acc, Long value)

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

getKind, getTypeInference

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

Methods inherited from interface org.apache.flink.table.functions.FunctionDefinition

getRequirements, isDeterministic, supportsConstantFolding

Constructor Detail

CountAggFunction

public CountAggFunction()

Method Detail

accumulate

public void accumulate(CountAggFunction.CountAccumulator acc,
                       Long value)

accumulate

public void accumulate(CountAggFunction.CountAccumulator acc)

retract

public void retract(CountAggFunction.CountAccumulator acc,
                    Long value)

retract

public void retract(CountAggFunction.CountAccumulator acc)

getValue

public Long getValue(CountAggFunction.CountAccumulator acc)

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<Long,CountAggFunction.CountAccumulator>

Parameters:

acc - the accumulator which contains the current intermediate results

Returns:

the aggregation result

merge

public void merge(CountAggFunction.CountAccumulator acc,
                  Iterable<CountAggFunction.CountAccumulator> its)

createAccumulator

public CountAggFunction.CountAccumulator 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<Long,CountAggFunction.CountAccumulator>

Returns:

the accumulator with the initial value