Package org.apache.spark.sql.connector.catalog

Class ColumnDefaultValue

Object

org.apache.spark.sql.connector.catalog.DefaultValue

org.apache.spark.sql.connector.catalog.ColumnDefaultValue

@Evolving
public class ColumnDefaultValue
extends DefaultValue

A class representing the default value of a column. It contains both the SQL string and literal value of the user-specified default value expression. The SQL string should be re-evaluated for each table writing command, which may produce different values if the default value expression is something like CURRENT_DATE(). The literal value is used to back-fill existing data if new columns with default value are added. Note: the back-fill can be lazy. The data sources can remember the column default value and let the reader fill the column value when reading existing data that do not have these new columns.

Constructor Summary

Constructors

Constructor	Description
ColumnDefaultValue(String sql, Expression expr, Literal<?> value)
ColumnDefaultValue(String sql, Literal<?> value)
ColumnDefaultValue(Expression expr, Literal<?> value)

Method Summary

Modifier and Type	Method	Description
boolean	equals(Object o)
final Expression	getExpression()	Returns the connector expression, if provided.
final String	getSql()	Returns the SQL representation, if provided.
Literal<?>	getValue()	Returns the default value literal.
int	hashCode()
String	toString()

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Details

ColumnDefaultValue

public ColumnDefaultValue(String sql,
 Literal<?> value)

ColumnDefaultValue

public ColumnDefaultValue(Expression expr,
 Literal<?> value)

ColumnDefaultValue

public ColumnDefaultValue(String sql,
 Expression expr,
 Literal<?> value)

Method Details

getValue

@Nullable
public Literal<?> getValue()

Returns the default value literal. This is the literal value corresponding to getSql(). For example if the SQL is "current_date()", this literal value will be the evaluated current_date() at the time the column was added/altered. Spark always sets this value when passing ColumnDefaultValue to createTable/alterTable, but Table.columns() may not do so as some data sources have its own system to do column default value back-fill.

equals

public boolean equals(Object o)

hashCode

public int hashCode()

toString

public String toString()

Overrides:

toString in class DefaultValue

getSql

@Nullable
public final String getSql()

Returns the SQL representation, if provided.

getExpression

@Nullable
public final Expression getExpression()

Returns the connector expression, if provided.