Package org.apache.flink.table.functions

Class ImperativeAggregateFunction<T,ACC>

java.lang.Object

org.apache.flink.table.functions.UserDefinedFunction

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

Type Parameters:

T - final result type of the aggregation

ACC - intermediate result type during the aggregation

All Implemented Interfaces:

Serializable, FunctionDefinition

Direct Known Subclasses:

AggregateFunction, TableAggregateFunction

@PublicEvolving
public abstract class ImperativeAggregateFunction<T,ACC>
extends UserDefinedFunction

Base class for user-defined AggregateFunction and TableAggregateFunction.

This class is used for unified handling of imperative aggregating functions. Concrete implementations should extend from AggregateFunction or TableAggregateFunction.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor	Description
ImperativeAggregateFunction()

Method Summary

Modifier and Type	Method	Description
abstract ACC	createAccumulator()	Creates and initializes the accumulator for this ImperativeAggregateFunction.
TypeInformation<ACC>	getAccumulatorType()	Deprecated. This method uses the old type system and is based on the old reflective extraction logic.
TypeInformation<T>	getResultType()	Deprecated. This method uses the old type system and is based on the old reflective extraction logic.

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

close, functionIdentifier, getTypeInference, 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

getKind, getRequirements, isDeterministic, supportsConstantFolding

Constructor Detail

ImperativeAggregateFunction

public ImperativeAggregateFunction()

Method Detail

createAccumulator

public abstract ACC createAccumulator()

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.

Returns:

the accumulator with the initial value

getResultType

@Deprecated
public TypeInformation<T> getResultType()

Deprecated.

This method uses the old type system and is based on the old reflective extraction logic. The method will be removed in future versions and is only called when using the deprecated TableEnvironment.registerFunction(...) method. The new reflective extraction logic (possibly enriched with DataTypeHint and FunctionHint) should be powerful enough to cover most use cases. For advanced users, it is possible to override UserDefinedFunction.getTypeInference(DataTypeFactory).

Returns the TypeInformation of the ImperativeAggregateFunction's result.

Returns:

The TypeInformation of the ImperativeAggregateFunction's result or null if the result type should be automatically inferred.

getAccumulatorType

@Deprecated
public TypeInformation<ACC> getAccumulatorType()

Deprecated.

This method uses the old type system and is based on the old reflective extraction logic. The method will be removed in future versions and is only called when using the deprecated TableEnvironment.registerFunction(...) method. The new reflective extraction logic (possibly enriched with DataTypeHint and FunctionHint) should be powerful enough to cover most use cases. For advanced users, it is possible to override UserDefinedFunction.getTypeInference(DataTypeFactory).

Returns the TypeInformation of the ImperativeAggregateFunction's accumulator.

Returns:

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