org.apache.paimon.types

Class DataTypeCasts

java.lang.Object

org.apache.paimon.types.DataTypeCasts

public final class DataTypeCasts
extends Object

Utilities for casting DataType.

Method Summary

Modifier and Type	Method and Description
static boolean	supportsCompatibleCast(DataType sourceType, DataType targetType) Returns whether the source type can be compatibly cast to the target type.
static boolean	supportsExplicitCast(DataType sourceType, DataType targetType) Returns whether the source type can be cast to the target type.
static boolean	supportsImplicitCast(DataType sourceType, DataType targetType) Returns whether the source type can be safely cast to the target type without loosing information.

Methods inherited from class java.lang.Object

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

Method Detail

supportsImplicitCast

public static boolean supportsImplicitCast(DataType sourceType,
                                           DataType targetType)

Returns whether the source type can be safely cast to the target type without loosing information.

Implicit casts are used for type widening and type generalization (finding a common supertype for a set of types). Implicit casts are similar to the Java semantics (e.g. this is not possible: int x = (String) z).

supportsExplicitCast

public static boolean supportsExplicitCast(DataType sourceType,
                                           DataType targetType)

Returns whether the source type can be cast to the target type.

Explicit casts correspond to the SQL cast specification and represent the logic behind a CAST(sourceType AS targetType) operation. For example, it allows for converting most types of the DataTypeFamily.PREDEFINED family to types of the DataTypeFamily.CHARACTER_STRING family.

supportsCompatibleCast

public static boolean supportsCompatibleCast(DataType sourceType,
                                             DataType targetType)

Returns whether the source type can be compatibly cast to the target type.

If two types are compatible, they should have the same underlying data structure. For example, CharType and VarCharType are both in the DataTypeFamily.CHARACTER_STRING family, meaning they both represent a character string. But the rest types are only compatible with themselves. For example, although IntType and BigIntType are both in the DataTypeFamily.NUMERIC family, they are not compatible because IntType represents a 4-byte signed integer while BigIntType represents an 8-byte signed integer. Especially, two DecimalTypes are compatible only when they have the same precision and scale.