org.apache.flink.table.functions

Class TemporalTableFunctionImpl

java.lang.Object

org.apache.flink.table.functions.UserDefinedFunction

org.apache.flink.table.functions.TableFunction<Row>

org.apache.flink.table.functions.TemporalTableFunction

org.apache.flink.table.functions.TemporalTableFunctionImpl

All Implemented Interfaces:

Serializable, FunctionDefinition

@Internal
public final class TemporalTableFunctionImpl
extends TemporalTableFunction

Class representing temporal table function over some history table. It takes one single argument, the timeAttribute, for which it returns matching version of the underlyingHistoryTable, from which this TemporalTableFunction was created.

This function shouldn't be evaluated. Instead calls to it should be rewritten by the optimiser into other operators (like Temporal Table Join).

See Also:

Serialized Form

Method Summary

Modifier and Type	Method and Description
static TemporalTableFunction	create(QueryOperation operationTree, Expression timeAttribute, Expression primaryKey)
void	eval(Timestamp t)
Expression	getPrimaryKey()
RowTypeInfo	getResultType() Returns the result type of the evaluation method.
Expression	getTimeAttribute()
TypeInference	getTypeInference(DataTypeFactory typeFactory) Returns the logic for performing type inference of a call to this function definition.
QueryOperation	getUnderlyingHistoryTable()

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

collect, finish, getKind, getParameterTypes, setCollector

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

close, functionIdentifier, open, 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.FunctionDefinition

getRequirements, isDeterministic, supportsConstantFolding

Method Detail

eval

public void eval(Timestamp t)

getTimeAttribute

public Expression getTimeAttribute()

getPrimaryKey

public Expression getPrimaryKey()

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 TableFunction<Row>

getResultType

public RowTypeInfo getResultType()

Description copied from class: TableFunction

Returns the result type of the evaluation method.

Overrides:

getResultType in class TableFunction<Row>

getUnderlyingHistoryTable

public QueryOperation getUnderlyingHistoryTable()

create

public static TemporalTableFunction create(QueryOperation operationTree,
                                           Expression timeAttribute,
                                           Expression primaryKey)