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

Class BatchApproxCountDistinctAggFunctions.ApproxCountDistinctAggFunction<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<Long,HllBuffer>

org.apache.flink.table.runtime.functions.aggregate.BatchApproxCountDistinctAggFunctions.ApproxCountDistinctAggFunction<T>

All Implemented Interfaces:

Serializable, FunctionDefinition

Direct Known Subclasses:

BatchApproxCountDistinctAggFunctions.ByteApproxCountDistinctAggFunction, BatchApproxCountDistinctAggFunctions.DateApproxCountDistinctAggFunction, BatchApproxCountDistinctAggFunctions.DecimalApproxCountDistinctAggFunction, BatchApproxCountDistinctAggFunctions.DoubleApproxCountDistinctAggFunction, BatchApproxCountDistinctAggFunctions.FloatApproxCountDistinctAggFunction, BatchApproxCountDistinctAggFunctions.IntApproxCountDistinctAggFunction, BatchApproxCountDistinctAggFunctions.LongApproxCountDistinctAggFunction, BatchApproxCountDistinctAggFunctions.ShortApproxCountDistinctAggFunction, BatchApproxCountDistinctAggFunctions.StringApproxCountDistinctAggFunction, BatchApproxCountDistinctAggFunctions.TimeApproxCountDistinctAggFunction, BatchApproxCountDistinctAggFunctions.TimestampApproxCountDistinctAggFunction, BatchApproxCountDistinctAggFunctions.TimestampLtzApproxCountDistinctAggFunction

Enclosing class:

BatchApproxCountDistinctAggFunctions

public abstract static class BatchApproxCountDistinctAggFunctions.ApproxCountDistinctAggFunction<T>
extends BuiltInAggregateFunction<Long,HllBuffer>

Base function for APPROX_COUNT_DISTINCT aggregate.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
ApproxCountDistinctAggFunction(LogicalType valueType)

Method Summary

Modifier and Type	Method and Description
void	accumulate(HllBuffer buffer, Object input)
HllBuffer	createAccumulator() Creates and initializes the accumulator for this ImperativeAggregateFunction.
DataType	getAccumulatorDataType()
List<DataType>	getArgumentDataTypes()
DataType	getOutputDataType()
Long	getValue(HllBuffer buffer) Called every time when an aggregation result should be materialized.
void	merge(HllBuffer buffer, Iterable<HllBuffer> it)
void	resetAccumulator(HllBuffer buffer)

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

ApproxCountDistinctAggFunction

public ApproxCountDistinctAggFunction(LogicalType valueType)

Method Detail

createAccumulator

public HllBuffer 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,HllBuffer>

Returns:

the accumulator with the initial value

accumulate

public void accumulate(HllBuffer buffer,
                       Object input)
                throws Exception

Throws:

Exception

merge

public void merge(HllBuffer buffer,
                  Iterable<HllBuffer> it)
           throws Exception

Throws:

Exception

resetAccumulator

public void resetAccumulator(HllBuffer buffer)

getValue

public Long getValue(HllBuffer buffer)

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,HllBuffer>

Parameters:

buffer - the accumulator which contains the current intermediate results

Returns:

the aggregation result

getArgumentDataTypes

public List<DataType> getArgumentDataTypes()

Overrides:

getArgumentDataTypes in class BuiltInAggregateFunction<Long,HllBuffer>

getAccumulatorDataType

public DataType getAccumulatorDataType()

Overrides:

getAccumulatorDataType in class BuiltInAggregateFunction<Long,HllBuffer>

getOutputDataType

public DataType getOutputDataType()

Overrides:

getOutputDataType in class BuiltInAggregateFunction<Long,HllBuffer>