org.apache.flink.table.functions.hive

Class HiveScalarFunction<UDFType>

java.lang.Object

org.apache.flink.table.functions.UserDefinedFunction

org.apache.flink.table.functions.ScalarFunction

org.apache.flink.table.functions.hive.HiveScalarFunction<UDFType>

All Implemented Interfaces:

Serializable, FunctionDefinition, HiveFunction<UDFType>

Direct Known Subclasses:

HiveGenericUDF, HiveSimpleUDF

@Internal
public abstract class HiveScalarFunction<UDFType>
extends ScalarFunction
implements HiveFunction<UDFType>

Abstract class to provide more information for Hive UDF and GenericUDF functions.

See Also:

Serialized Form

Nested Class Summary

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

HiveFunction.HiveFunctionInputStrategy, HiveFunction.HiveFunctionOutputStrategy

Field Summary

Fields

Modifier and Type	Field and Description
protected HiveFunctionArguments	arguments
protected UDFType	function
protected HiveFunctionWrapper<UDFType>	hiveFunctionWrapper
protected org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector	returnInspector

Method Summary

Modifier and Type	Method and Description
Object	eval(Object... args)
protected abstract Object	evalInternal(Object[] args) Evaluation logical, args will be wrapped when is a single array.
HiveFunctionWrapper<UDFType>	getFunctionWrapper() Gets the wrapper for the Hive function.
TypeInference	getTypeInference(DataTypeFactory typeFactory) Returns the logic for performing type inference of a call to this function definition.
boolean	isDeterministic() Returns information about the determinism of the function's results.
void	open(FunctionContext context) Setup method for user-defined function.
protected abstract void	openInternal() See UserDefinedFunction.open(FunctionContext).
void	setArguments(CallContext callContext) Sets input arguments for the function.

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

getKind, getParameterTypes, getResultType

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

close, functionIdentifier, 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.hive.HiveFunction

createTypeInference, inferReturnType

Methods inherited from interface org.apache.flink.table.functions.FunctionDefinition

getRequirements, supportsConstantFolding

Field Detail

hiveFunctionWrapper

protected final HiveFunctionWrapper<UDFType> hiveFunctionWrapper

arguments

protected HiveFunctionArguments arguments

function

protected transient UDFType function

returnInspector

protected transient org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector returnInspector

Method Detail

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

open

public void open(FunctionContext context)

Description copied from class: UserDefinedFunction

Setup method for user-defined function. It can be used for initialization work. By default, this method does nothing.

Overrides:

open in class UserDefinedFunction

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 ScalarFunction

openInternal

protected abstract void openInternal()

See UserDefinedFunction.open(FunctionContext).

eval

public Object eval(Object... args)

evalInternal

protected abstract Object evalInternal(Object[] args)

Evaluation logical, args will be wrapped when is a single array.

setArguments

public void setArguments(CallContext callContext)

Description copied from interface: HiveFunction

Sets input arguments for the function.

Specified by:

setArguments in interface HiveFunction<UDFType>

getFunctionWrapper

public HiveFunctionWrapper<UDFType> getFunctionWrapper()

Description copied from interface: HiveFunction

Gets the wrapper for the Hive function.

Specified by:

getFunctionWrapper in interface HiveFunction<UDFType>