Package org.apache.flink.table.catalog

Class Column

java.lang.Object

org.apache.flink.table.catalog.Column

Direct Known Subclasses:

Column.ComputedColumn, Column.MetadataColumn, Column.PhysicalColumn

@PublicEvolving
public abstract class Column
extends Object

Representation of a column in a ResolvedSchema.

A table column describes either a Column.PhysicalColumn, Column.ComputedColumn, or Column.MetadataColumn.

Every column is fully resolved. The enclosed DataType indicates whether the column is a time attribute and thus might differ from the original data type.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Column.ComputedColumn	Representation of a computed column.
static class	Column.MetadataColumn	Representation of a metadata column.
static class	Column.PhysicalColumn	Representation of a physical column.

Field Summary

Fields

Modifier and Type	Field	Description
protected String	comment
protected DataType	dataType
protected String	name

Method Summary

Modifier and Type	Method	Description
String	asSummaryString()	Returns a string that summarizes this column for printing to a console.
static Column.ComputedColumn	computed(String name, ResolvedExpression expression)	Creates a computed column that is computed from the given ResolvedExpression.
abstract Column	copy(DataType newType)	Returns a copy of the column with a replaced DataType.
boolean	equals(Object o)
abstract Optional<String>	explainExtras()	Returns an explanation of specific column extras next to name and type.
Optional<String>	getComment()	Returns the comment of this column.
DataType	getDataType()	Returns the data type of this column.
String	getName()	Returns the name of this column.
int	hashCode()
abstract boolean	isPersisted()	Returns whether the given column is persisted in a sink operation.
abstract boolean	isPhysical()	Returns whether the given column is a physical column of a table; neither computed nor metadata.
static Column.MetadataColumn	metadata(String name, DataType dataType, String metadataKey, boolean isVirtual)	Creates a metadata column from metadata of the given column name or from metadata of the given key (if not null).
static Column.PhysicalColumn	physical(String name, DataType dataType)	Creates a regular table column that represents physical data.
String	toString()
abstract Column	withComment(String comment)	Add the comment to the column and return the new object.

Methods inherited from class java.lang.Object

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

Field Detail

name

protected final String name

dataType

protected final DataType dataType

comment

@Nullable
protected final String comment

Method Detail

physical

public static Column.PhysicalColumn physical(String name,
                                             DataType dataType)

Creates a regular table column that represents physical data.

computed

public static Column.ComputedColumn computed(String name,
                                             ResolvedExpression expression)

Creates a computed column that is computed from the given ResolvedExpression.

metadata

public static Column.MetadataColumn metadata(String name,
                                             DataType dataType,
                                             @Nullable
                                             String metadataKey,
                                             boolean isVirtual)

Creates a metadata column from metadata of the given column name or from metadata of the given key (if not null).

Allows to specify whether the column is virtual or not.

withComment

public abstract Column withComment(@Nullable
                                   String comment)

Add the comment to the column and return the new object.

isPhysical

public abstract boolean isPhysical()

Returns whether the given column is a physical column of a table; neither computed nor metadata.

isPersisted

public abstract boolean isPersisted()

Returns whether the given column is persisted in a sink operation.

getDataType

public DataType getDataType()

Returns the data type of this column.

getName

public String getName()

Returns the name of this column.

getComment

public Optional<String> getComment()

Returns the comment of this column.

asSummaryString

public String asSummaryString()

Returns a string that summarizes this column for printing to a console.

explainExtras

public abstract Optional<String> explainExtras()

Returns an explanation of specific column extras next to name and type.

copy

public abstract Column copy(DataType newType)

Returns a copy of the column with a replaced DataType.

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object