org.apache.flink.table.functions

Class BuiltInFunctionDefinition

java.lang.Object

org.apache.flink.table.functions.BuiltInFunctionDefinition

All Implemented Interfaces:

FunctionDefinition, SpecializedFunction

@Internal
public final class BuiltInFunctionDefinition
extends Object
implements SpecializedFunction

Definition of a built-in function. It enables unique identification across different modules by reference equality.

Compared to regular FunctionDefinition, built-in functions have a default name. This default name is used to look up the function in a catalog during resolution. However, note that every built-in function is actually fully qualified by a name and a version. Internal functions are required to have a name that includes the version (e.g. $REPLICATE_ROWS$1). The most recent version of a regular function is picked during a lookup if a call does not reference an internal function.

Equality is defined by reference equality.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	BuiltInFunctionDefinition.Builder Builder for fluent definition of built-in functions.

Nested classes/interfaces inherited from interface org.apache.flink.table.functions.SpecializedFunction

SpecializedFunction.ExpressionEvaluator, SpecializedFunction.ExpressionEvaluatorFactory, SpecializedFunction.SpecializedContext

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_VERSION

Method Summary

Modifier and Type	Method and Description
SqlCallSyntax	getCallSyntax()
FunctionKind	getKind() Returns the kind of function this definition describes.
String	getName()
String	getQualifiedName()
Optional<String>	getRuntimeClass()
String	getSqlName()
TypeInference	getTypeInference(DataTypeFactory typeFactory) Returns the logic for performing type inference of a call to this function definition.
Optional<Integer>	getVersion()
boolean	hasRuntimeImplementation()
boolean	isDeterministic() Returns information about the determinism of the function's results.
boolean	isInternal()
static BuiltInFunctionDefinition.Builder	newBuilder() Builder for configuring and creating instances of BuiltInFunctionDefinition.
static String	qualifyFunctionName(String name, int version)
UserDefinedFunction	specialize(SpecializedFunction.SpecializedContext context) Provides a runtime implementation that is specialized for the given call and session.
String	toString()
static void	validateFunction(String name, Integer version, boolean isInternal)

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, supportsConstantFolding

Field Detail

DEFAULT_VERSION

public static final int DEFAULT_VERSION

See Also:

Constant Field Values

Method Detail

newBuilder

public static BuiltInFunctionDefinition.Builder newBuilder()

Builder for configuring and creating instances of BuiltInFunctionDefinition.

getName

public String getName()

getSqlName

public String getSqlName()

getVersion

public Optional<Integer> getVersion()

getRuntimeClass

public Optional<String> getRuntimeClass()

hasRuntimeImplementation

public boolean hasRuntimeImplementation()

isInternal

public boolean isInternal()

getQualifiedName

public String getQualifiedName()

specialize

public UserDefinedFunction specialize(SpecializedFunction.SpecializedContext context)

Description copied from interface: SpecializedFunction

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.

Specified by:

specialize in interface SpecializedFunction

getKind

public FunctionKind getKind()

Description copied from interface: FunctionDefinition

Returns the kind of function this definition describes.

Specified by:

getKind in interface FunctionDefinition

getTypeInference

public TypeInference getTypeInference(DataTypeFactory typeFactory)

Description copied from interface: FunctionDefinition

Returns the logic for performing type inference of a call to this function definition.

The type inference process is responsible for inferring unknown types of input arguments, validating input arguments, and producing result types. The type inference process happens independent of a function body. The output of the type inference is used to search for a corresponding runtime implementation.

Instances of type inference can be created by using TypeInference.newBuilder().

See BuiltInFunctionDefinitions for concrete usage examples.

Specified by:

getTypeInference in interface FunctionDefinition

getCallSyntax

public SqlCallSyntax getCallSyntax()

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 purely functional like random(), date(), now(), ... this method must return false.

Furthermore, return false if the planner should always execute this function on the cluster side. In other words: the planner should not perform constant expression reduction during planning for constant calls to this function.

Specified by:

isDeterministic in interface FunctionDefinition

toString

public String toString()

Overrides:

toString in class Object

validateFunction

public static void validateFunction(String name,
                                    @Nullable
                                    Integer version,
                                    boolean isInternal)

qualifyFunctionName

public static String qualifyFunctionName(String name,
                                         int version)