org.apache.flink.table.types.inference.strategies

Class ComparableTypeStrategy

java.lang.Object

org.apache.flink.table.types.inference.strategies.ComparableTypeStrategy

All Implemented Interfaces:

InputTypeStrategy

@Internal
public final class ComparableTypeStrategy
extends Object
implements InputTypeStrategy

An InputTypeStrategy that checks if all input arguments can be compared with each other with the minimal provided comparison.

It requires at least one argument. In case of one argument, the argument must be comparable with itself (e.g. for aggregations).

For the rules which types are comparable with which types see LogicalTypeChecks#areComparable(LogicalType, LogicalType, StructuredComparison).

Constructor Summary

Constructors

Constructor and Description
ComparableTypeStrategy(ConstantArgumentCount argumentCount, StructuredType.StructuredComparison requiredComparison)

Method Summary

Modifier and Type	Method and Description
ArgumentCount	getArgumentCount() Initial input validation based on the number of arguments.
List<Signature>	getExpectedSignatures(FunctionDefinition definition) Returns a summary of the function's expected signatures.
Optional<List<DataType>>	inferInputTypes(CallContext callContext, boolean throwOnFailure) Main logic for inferring and validating the input arguments.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ComparableTypeStrategy

public ComparableTypeStrategy(ConstantArgumentCount argumentCount,
                              StructuredType.StructuredComparison requiredComparison)

Method Detail

getArgumentCount

public ArgumentCount getArgumentCount()

Description copied from interface: InputTypeStrategy

Initial input validation based on the number of arguments.

Specified by:

getArgumentCount in interface InputTypeStrategy

inferInputTypes

public Optional<List<DataType>> inferInputTypes(CallContext callContext,
                                                boolean throwOnFailure)

Description copied from interface: InputTypeStrategy

Main logic for inferring and validating the input arguments. Returns a list of argument data types that are valid for the given call. If the returned types differ from CallContext.getArgumentDataTypes(), a casting operation can be inserted. An empty result means that the given input is invalid.

Specified by:

inferInputTypes in interface InputTypeStrategy

Parameters:

callContext - provides details about the function call

throwOnFailure - whether this function is allowed to throw an ValidationException with a meaningful exception in case the inference is not successful or if this function should simply return an empty result.

Returns:

three-state result for either "true, same data types as arguments", "true, but arguments must be casted to returned data types", or "false, no inferred data types could be found"

See Also:

CallContext.newValidationError(String, Object...)

getExpectedSignatures

public List<Signature> getExpectedSignatures(FunctionDefinition definition)

Description copied from interface: InputTypeStrategy

Returns a summary of the function's expected signatures.

Specified by:

getExpectedSignatures in interface InputTypeStrategy

Parameters:

definition - the function definition that defines the function currently being called.