org.apache.flink.table.types.logical

类 VarCharType

java.lang.Object

org.apache.flink.table.types.logical.LogicalType

org.apache.flink.table.types.logical.VarCharType

所有已实现的接口:

Serializable

@PublicEvolving
public final class VarCharType
extends LogicalType

Logical type of a variable-length character string.

The serialized string representation is VARCHAR(n) where n is the maximum number of code points. n must have a value between 1 and Integer.MAX_VALUE (both inclusive). If no length is specified, n is equal to 1. STRING is a synonym for VARCHAR(2147483647).

For enabling type inference of a zero-length character string literal to a variable-length character string, this type does also support n to be 0. However, this is not exposed through the API.

A conversion from and to byte[] assumes UTF-8 encoding.

另请参阅:

序列化表格

字段概要

字段

限定符和类型	字段和说明
static int	DEFAULT_LENGTH
static int	EMPTY_LITERAL_LENGTH
static int	MAX_LENGTH
static int	MIN_LENGTH

构造器概要

构造器

构造器和说明
VarCharType()
VarCharType(boolean isNullable, int length)
VarCharType(int length)

方法概要

限定符和类型	方法和说明
<R> R	accept(LogicalTypeVisitor<R> visitor)
String	asSerializableString() Returns a string that fully serializes this instance.
String	asSummaryString() Returns a string that summarizes this type for printing to a console.
LogicalType	copy(boolean isNullable) Returns a deep copy of this type with possibly different nullability.
boolean	equals(Object o)
List<LogicalType>	getChildren()
Class<?>	getDefaultConversion() Returns the default conversion class.
int	getLength()
int	hashCode()
static VarCharType	ofEmptyLiteral() The SQL standard defines that character string literals are allowed to be zero-length strings (i.e., to contain no characters) even though it is not permitted to declare a type that is zero.
boolean	supportsInputConversion(Class<?> clazz) Returns whether an instance of the given class can be represented as a value of this logical type when entering the table ecosystem.
boolean	supportsOutputConversion(Class<?> clazz) Returns whether a value of this logical type can be represented as an instance of the given class when leaving the table ecosystem.

从类继承的方法 org.apache.flink.table.types.logical.LogicalType

conversionSet, copy, getTypeRoot, isNullable, toString, withNullability

从类继承的方法 java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

字段详细资料

EMPTY_LITERAL_LENGTH

public static final int EMPTY_LITERAL_LENGTH

另请参阅:

常量字段值

MIN_LENGTH

public static final int MIN_LENGTH

另请参阅:

常量字段值

MAX_LENGTH

public static final int MAX_LENGTH

另请参阅:

常量字段值

DEFAULT_LENGTH

public static final int DEFAULT_LENGTH

另请参阅:

常量字段值

构造器详细资料

VarCharType

public VarCharType(boolean isNullable,
                   int length)

VarCharType

public VarCharType(int length)

VarCharType

public VarCharType()

方法详细资料

ofEmptyLiteral

public static VarCharType ofEmptyLiteral()

The SQL standard defines that character string literals are allowed to be zero-length strings (i.e., to contain no characters) even though it is not permitted to declare a type that is zero. This has also implications on variable-length character strings during type inference because any fixed-length character string should be convertible to a variable-length one.

This method enables this special kind of character string.

Zero-length character strings have no serializable string representation.

getLength

public int getLength()

copy

public LogicalType copy(boolean isNullable)

从类复制的说明: LogicalType

Returns a deep copy of this type with possibly different nullability.

指定者:

copy 在类中 LogicalType

参数:

isNullable - the intended nullability of the copied type

返回:

a deep copy

asSerializableString

public String asSerializableString()

从类复制的说明: 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.

指定者:

asSerializableString 在类中 LogicalType

返回:

detailed string for transmission or persistence

asSummaryString

public String asSummaryString()

从类复制的说明: LogicalType

Returns a string that summarizes this type for printing to a console. An implementation might shorten long names or skips very specific properties.

Use LogicalType.asSerializableString() for a type string that fully serializes this instance.

覆盖:

asSummaryString 在类中 LogicalType

返回:

summary string of this type for debugging purposes

supportsInputConversion

public boolean supportsInputConversion(Class<?> clazz)

从类复制的说明: 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.

指定者:

supportsInputConversion 在类中 LogicalType

参数:

clazz - input class to be converted into this logical type

返回:

flag that indicates if instances of this class can be used as input into the table ecosystem

另请参阅:

LogicalType.getDefaultConversion()

supportsOutputConversion

public boolean supportsOutputConversion(Class<?> clazz)

从类复制的说明: 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.

指定者:

supportsOutputConversion 在类中 LogicalType

参数:

clazz - output class to be converted from this logical type

返回:

flag that indicates if instances of this class can be used as output from the table ecosystem

另请参阅:

LogicalType.getDefaultConversion()

getDefaultConversion

public Class<?> getDefaultConversion()

从类复制的说明: LogicalType

Returns the default conversion class. A value of this logical type is expected to be an instance of the given class when entering or is represented as an instance of the given class when leaving the table ecosystem if no other conversion has been specified.

For example, java.lang.Long is the default input and output for BIGINT.

指定者:

getDefaultConversion 在类中 LogicalType

返回:

default class to represent values of this logical type

另请参阅:

LogicalType.supportsInputConversion(Class), LogicalType.supportsOutputConversion(Class)

getChildren

public List<LogicalType> getChildren()

指定者:

getChildren 在类中 LogicalType

accept

public <R> R accept(LogicalTypeVisitor<R> visitor)

指定者:

accept 在类中 LogicalType

equals

public boolean equals(Object o)

覆盖:

equals 在类中 LogicalType

hashCode

public int hashCode()

覆盖:

hashCode 在类中 LogicalType