Package 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.

  • Field Details

  • Method Details

    • 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)