org.apache.flink.table.planner.functions.aggfunctions

Class LastValueAggFunction<T>

java.lang.Object

org.apache.flink.table.functions.UserDefinedFunction

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

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

org.apache.flink.table.planner.functions.aggfunctions.LastValueAggFunction<T>

All Implemented Interfaces:

Serializable, FunctionDefinition

Direct Known Subclasses:

LastValueAggFunction.BooleanLastValueAggFunction, LastValueAggFunction.ByteLastValueAggFunction, LastValueAggFunction.DecimalLastValueAggFunction, LastValueAggFunction.DoubleLastValueAggFunction, LastValueAggFunction.FloatLastValueAggFunction, LastValueAggFunction.IntLastValueAggFunction, LastValueAggFunction.LongLastValueAggFunction, LastValueAggFunction.ShortLastValueAggFunction, LastValueAggFunction.StringLastValueAggFunction

public class LastValueAggFunction<T>
extends AggregateFunction<T,GenericRowData>

built-in LastValue aggregate function.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	LastValueAggFunction.BooleanLastValueAggFunction Built-in Boolean LastValue aggregate function.
static class	LastValueAggFunction.ByteLastValueAggFunction Built-in Byte LastValue aggregate function.
static class	LastValueAggFunction.DecimalLastValueAggFunction Built-in DecimalData LastValue aggregate function.
static class	LastValueAggFunction.DoubleLastValueAggFunction Built-in Double LastValue aggregate function.
static class	LastValueAggFunction.FloatLastValueAggFunction Built-in Float LastValue aggregate function.
static class	LastValueAggFunction.IntLastValueAggFunction Built-in Int LastValue aggregate function.
static class	LastValueAggFunction.LongLastValueAggFunction Built-in Long LastValue aggregate function.
static class	LastValueAggFunction.ShortLastValueAggFunction Built-in Short LastValue aggregate function.
static class	LastValueAggFunction.StringLastValueAggFunction Built-in String LastValue aggregate function.

Constructor Summary

Constructors

Constructor and Description
LastValueAggFunction()

Method Summary

Modifier and Type	Method and Description
void	accumulate(GenericRowData acc, Object value)
void	accumulate(GenericRowData acc, Object value, Long order)
GenericRowData	createAccumulator() Creates and initializes the accumulator for this UserDefinedAggregateFunction.
TypeInformation<GenericRowData>	getAccumulatorType() Returns the TypeInformation of the UserDefinedAggregateFunction's accumulator.
T	getValue(GenericRowData acc) Called every time when an aggregation result should be materialized.
boolean	isDeterministic() Returns information about the determinism of the function's results.
void	resetAccumulator(GenericRowData acc)

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

getKind, getRequirements, getTypeInference, requiresOver

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

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

LastValueAggFunction

public LastValueAggFunction()

Method Detail

isDeterministic

public boolean isDeterministic()

Description copied from interface: FunctionDefinition

Returns information about the determinism of the function's results.

It returns true if and only if a call to this function is guaranteed to always return the same result given the same parameters. true is assumed by default. If the function is not pure functional like random(), date(), now(), ... this method must return false.

createAccumulator

public GenericRowData createAccumulator()

Description copied from class: UserDefinedAggregateFunction

Creates and initializes the accumulator for this UserDefinedAggregateFunction. The accumulator is used to keep the aggregated values which are needed to compute an aggregation result.

Specified by:

createAccumulator in class UserDefinedAggregateFunction<T,GenericRowData>

Returns:

the accumulator with the initial value

accumulate

public void accumulate(GenericRowData acc,
                       Object value)

accumulate

public void accumulate(GenericRowData acc,
                       Object value,
                       Long order)

resetAccumulator

public void resetAccumulator(GenericRowData acc)

getValue

public T getValue(GenericRowData 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 arrive) or the final result of the aggregation.

Specified by:

getValue in class AggregateFunction<T,GenericRowData>

Parameters:

acc - the accumulator which contains the current aggregated results

Returns:

the aggregation result

getAccumulatorType

public TypeInformation<GenericRowData> getAccumulatorType()

Description copied from class: UserDefinedAggregateFunction

Returns the TypeInformation of the UserDefinedAggregateFunction's accumulator.

Overrides:

getAccumulatorType in class UserDefinedAggregateFunction<T,GenericRowData>

Returns:

The TypeInformation of the UserDefinedAggregateFunction's accumulator or null if the accumulator type should be automatically inferred.