Package org.apache.flink.table.functions.python

Class PythonAggregateFunction

    • Constructor Detail

      • PythonAggregateFunction

        public PythonAggregateFunction​(String name,
                               byte[] serializedAggregateFunction,
                               DataType[] inputTypes,
                               DataType resultType,
                               DataType accumulatorType,
                               PythonFunctionKind pythonFunctionKind,
                               boolean deterministic,
                               boolean takesRowAsInput,
                               PythonEnv pythonEnv)

      • PythonAggregateFunction

        public PythonAggregateFunction​(String name,
                               byte[] serializedAggregateFunction,
                               String[] inputTypesString,
                               String resultTypeString,
                               String accumulatorTypeString,
                               PythonFunctionKind pythonFunctionKind,
                               boolean deterministic,
                               boolean takesRowAsInput,
                               PythonEnv pythonEnv)

      • PythonAggregateFunction

        public PythonAggregateFunction​(String name,
                               byte[] serializedAggregateFunction,
                               PythonFunctionKind pythonFunctionKind,
                               boolean deterministic,
                               boolean takesRowAsInput,
                               PythonEnv pythonEnv)

    • Method Detail

      • accumulate

        public void accumulate​(Object accumulator,
                       Object... args)

      • getValue

        public Object getValue​(Object accumulator)
        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 arrives) or the final result of the aggregation.
        Specified by:
        getValue in class AggregateFunction
        Parameters:
        accumulator - the accumulator which contains the current intermediate results
        Returns:
        the aggregation result

      • takesRowAsInput

        public boolean takesRowAsInput()
        Description copied from interface: PythonFunction
        Returns Whether the Python function takes row as input instead of each columns of a row.
        Specified by:
        takesRowAsInput in interface PythonFunction

      • 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

      • getTypeInference

        public TypeInference getTypeInference​(DataTypeFactory typeFactory)
        Description copied from class: UserDefinedFunction
        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.

        The type inference for user-defined functions is automatically extracted using reflection. It does this by analyzing implementation methods such as eval() or accumulate() and the generic parameters of a function class if present. If the reflective information is not sufficient, it can be supported and enriched with DataTypeHint and FunctionHint annotations.

        Note: Overriding this method is only recommended for advanced users. If a custom type inference is specified, it is the responsibility of the implementer to make sure that the output of the type inference process matches with the implementation method:

        The implementation method must comply with each DataType.getConversionClass() returned by the type inference. For example, if DataTypes.TIMESTAMP(3).bridgedTo(java.sql.Timestamp.class) is an expected argument type, the method must accept a call eval(java.sql.Timestamp).

        Regular Java calling semantics (including type widening and autoboxing) are applied when calling an implementation method which means that the signature can be eval(java.lang.Object).

        The runtime will take care of converting the data to the data format specified by the DataType.getConversionClass() coming from the type inference logic.

        Specified by:
        getTypeInference in interface FunctionDefinition
        Overrides:
        getTypeInference in class AggregateFunction