org.apache.flink.table.functions

接口 SpecializedFunction

所有超级接口:

FunctionDefinition

所有已知实现类:

BuiltInFunctionDefinition

@PublicEvolving
public interface SpecializedFunction
extends FunctionDefinition

A FunctionDefinition that can provide a runtime implementation (i.e. the function's body) that is specialized for the given call and session.

The planner tries to defer the specialization until shortly before code generation, where the information given by a FunctionDefinition is not enough anymore and a subclass of UserDefinedFunction is required for runtime.

This interface is useful when the runtime code should know about information that is only available after planning (e.g. local session time zone or precision/scale of decimal return type).

A UserDefinedFunction that is registered in the API is implicitly specialized but can also implement this interface to reconfigure itself before runtime.

Note: This interface is a rather low level kind of function but useful for advanced users.

嵌套类概要

嵌套类

限定符和类型	接口和说明
static interface	SpecializedFunction.SpecializedContext Provides call and session information for the specialized function.

方法概要

限定符和类型	方法和说明
UserDefinedFunction	specialize(SpecializedFunction.SpecializedContext context) Provides a runtime implementation that is specialized for the given call and session.

从接口继承的方法 org.apache.flink.table.functions.FunctionDefinition

getKind, getRequirements, getTypeInference, isDeterministic

方法详细资料

specialize

UserDefinedFunction specialize(SpecializedFunction.SpecializedContext context)

Provides a runtime implementation that is specialized for the given call and session.

The method must return an instance of UserDefinedFunction or throw a TableException if the given call is not supported. The returned instance must have the same FunctionDefinition semantics but can have a different FunctionDefinition.getTypeInference(DataTypeFactory) implementation.