Package org.apache.flink.table.types.logical

Class DistinctType

  • All Implemented Interfaces:
    Serializable
    @PublicEvolving
public final class DistinctType
extends UserDefinedType
    Logical type of a user-defined distinct type. This type is currently not fully supported in the planner and remains future work.

    A distinct type specifies an identifier and is backed by a source type. A distinct type has the same internal representation as the source type, but is considered to be a separate and incompatible data type for most operations. Compared to the SQL standard, every non-user-defined type can be used as a source type.

    A distinct type can always be cast to its source type and vice versa.

    Distinct types are implicitly final and do not support super types.

    Most other properties are forwarded from the source type. Thus, ordering and comparison among the same distinct types are supported.

    The serialized string representation is the fully qualified name of this type which means that the type must have been registered in a catalog.

    See Also:
    Serialized Form

    • Method Detail

      • copy

        public LogicalType copy​(boolean isNullable)
        Description copied from class: LogicalType
        Returns a deep copy of this type with possibly different nullability.
        Specified by:
        copy in class LogicalType
        Parameters:
        isNullable - the intended nullability of the copied type
        Returns:
        a deep copy

      • asSerializableString

        public String asSerializableString()
        Description copied from class: LogicalType
        Returns a string that fully serializes this instance. The serialized string can be used for transmitting or persisting a type.

        See LogicalTypeParser for the reverse operation.

        Specified by:
        asSerializableString in class LogicalType
        Returns:
        detailed string for transmission or persistence

      • supportsInputConversion

        public boolean supportsInputConversion​(Class<?> clazz)
        Description copied from class: LogicalType
        Returns whether an instance of the given class can be represented as a value of this logical type when entering the table ecosystem. This method helps for the interoperability between JVM-based languages and the relational type system.

        A supported conversion directly maps an input class to a logical type without loss of precision or type widening.

        For example, java.lang.Long or long can be used as input for BIGINT independent of the set nullability.

        Specified by:
        supportsInputConversion in class LogicalType
        Parameters:
        clazz - input class to be converted into this logical type
        Returns:
        flag that indicates if instances of this class can be used as input into the table ecosystem
        See Also:
        LogicalType.getDefaultConversion()

      • supportsOutputConversion

        public boolean supportsOutputConversion​(Class<?> clazz)
        Description copied from class: LogicalType
        Returns whether a value of this logical type can be represented as an instance of the given class when leaving the table ecosystem. This method helps for the interoperability between JVM-based languages and the relational type system.

        A supported conversion directly maps a logical type to an output class without loss of precision or type widening.

        For example, java.lang.Long or long can be used as output for BIGINT if the type is not nullable. If the type is nullable, only java.lang.Long can represent this.

        Specified by:
        supportsOutputConversion in class LogicalType
        Parameters:
        clazz - output class to be converted from this logical type
        Returns:
        flag that indicates if instances of this class can be used as output from the table ecosystem
        See Also:
        LogicalType.getDefaultConversion()