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ALTER FOREIGN TABLE(7)	 PostgreSQL 17.5 Documentation	ALTER FOREIGN TABLE(7)

NAME
       ALTER_FOREIGN_TABLE - change the	definition of a	foreign	table

SYNOPSIS
       ALTER FOREIGN TABLE [ IF	EXISTS ] [ ONLY	] name [ * ]
	   action [, ... ]
       ALTER FOREIGN TABLE [ IF	EXISTS ] [ ONLY	] name [ * ]
	   RENAME [ COLUMN ] column_name TO new_column_name
       ALTER FOREIGN TABLE [ IF	EXISTS ] name
	   RENAME TO new_name
       ALTER FOREIGN TABLE [ IF	EXISTS ] name
	   SET SCHEMA new_schema

       where action is one of:

	   ADD [ COLUMN	] column_name data_type	[ COLLATE collation ] [	column_constraint [ ...	] ]
	   DROP	[ COLUMN ] [ IF	EXISTS ] column_name [ RESTRICT	| CASCADE ]
	   ALTER [ COLUMN ] column_name	[ SET DATA ] TYPE data_type [ COLLATE collation	]
	   ALTER [ COLUMN ] column_name	SET DEFAULT expression
	   ALTER [ COLUMN ] column_name	DROP DEFAULT
	   ALTER [ COLUMN ] column_name	{ SET |	DROP } NOT NULL
	   ALTER [ COLUMN ] column_name	SET STATISTICS integer
	   ALTER [ COLUMN ] column_name	SET ( attribute_option = value [, ... ]	)
	   ALTER [ COLUMN ] column_name	RESET (	attribute_option [, ...	] )
	   ALTER [ COLUMN ] column_name	SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN | DEFAULT }
	   ALTER [ COLUMN ] column_name	OPTIONS	( [ ADD	| SET |	DROP ] option ['value']	[, ... ])
	   ADD table_constraint	[ NOT VALID ]
	   VALIDATE CONSTRAINT constraint_name
	   DROP	CONSTRAINT [ IF	EXISTS ]  constraint_name [ RESTRICT | CASCADE ]
	   DISABLE TRIGGER [ trigger_name | ALL	| USER ]
	   ENABLE TRIGGER [ trigger_name | ALL | USER ]
	   ENABLE REPLICA TRIGGER trigger_name
	   ENABLE ALWAYS TRIGGER trigger_name
	   SET WITHOUT OIDS
	   INHERIT parent_table
	   NO INHERIT parent_table
	   OWNER TO { new_owner	| CURRENT_ROLE | CURRENT_USER |	SESSION_USER }
	   OPTIONS ( [ ADD | SET | DROP	] option ['value'] [, ... ])

DESCRIPTION
       ALTER FOREIGN TABLE changes the definition of an	existing foreign
       table. There are	several	subforms:

       ADD COLUMN
	   This	form adds a new	column to the foreign table, using the same
	   syntax as CREATE FOREIGN TABLE. Unlike the case when	adding a
	   column to a regular table, nothing happens to the underlying
	   storage: this action	simply declares	that some new column is	now
	   accessible through the foreign table.

       DROP COLUMN [ IF	EXISTS ]
	   This	form drops a column from a foreign table. You will need	to say
	   CASCADE if anything outside the table depends on the	column;	for
	   example, views. If IF EXISTS	is specified and the column does not
	   exist, no error is thrown. In this case a notice is issued instead.

       SET DATA	TYPE
	   This	form changes the type of a column of a foreign table. Again,
	   this	has no effect on any underlying	storage: this action simply
	   changes the type that PostgreSQL believes the column	to have.

       SET/DROP	DEFAULT
	   These forms set or remove the default value for a column. Default
	   values only apply in	subsequent INSERT or UPDATE commands; they do
	   not cause rows already in the table to change.

       SET/DROP	NOT NULL
	   Mark	a column as allowing, or not allowing, null values.

       SET STATISTICS
	   This	form sets the per-column statistics-gathering target for
	   subsequent ANALYZE operations. See the similar form of ALTER	TABLE
	   for more details.

       SET ( attribute_option =	value [, ... ] )
       RESET ( attribute_option	[, ... ] )
	   This	form sets or resets per-attribute options. See the similar
	   form	of ALTER TABLE for more	details.

       SET STORAGE
	   This	form sets the storage mode for a column. See the similar form
	   of ALTER TABLE for more details. Note that the storage mode has no
	   effect unless the table's foreign-data wrapper chooses to pay
	   attention to	it.

       ADD table_constraint [ NOT VALID	]
	   This	form adds a new	constraint to a	foreign	table, using the same
	   syntax as CREATE FOREIGN TABLE. Currently only CHECK	constraints
	   are supported.

	   Unlike the case when	adding a constraint to a regular table,
	   nothing is done to verify the constraint is correct;	rather,	this
	   action simply declares that some new	condition should be assumed to
	   hold	for all	rows in	the foreign table. (See	the discussion in
	   CREATE FOREIGN TABLE.) If the constraint is marked NOT VALID, then
	   it isn't assumed to hold, but is only recorded for possible future
	   use.

       VALIDATE	CONSTRAINT
	   This	form marks as valid a constraint that was previously marked as
	   NOT VALID. No action	is taken to verify the constraint, but future
	   queries will	assume that it holds.

       DROP CONSTRAINT [ IF EXISTS ]
	   This	form drops the specified constraint on a foreign table.	If IF
	   EXISTS is specified and the constraint does not exist, no error is
	   thrown. In this case	a notice is issued instead.

       DISABLE/ENABLE [	REPLICA	| ALWAYS ] TRIGGER
	   These forms configure the firing of trigger(s) belonging to the
	   foreign table. See the similar form of ALTER	TABLE for more
	   details.

       SET WITHOUT OIDS
	   Backward compatibility syntax for removing the oid system column.
	   As oid system columns cannot	be added anymore, this never has an
	   effect.

       INHERIT parent_table
	   This	form adds the target foreign table as a	new child of the
	   specified parent table. See the similar form	of ALTER TABLE for
	   more	details.

       NO INHERIT parent_table
	   This	form removes the target	foreign	table from the list of
	   children of the specified parent table.

       OWNER
	   This	form changes the owner of the foreign table to the specified
	   user.

       OPTIONS ( [ ADD | SET | DROP ] option ['value'] [, ... ]	)
	   Change options for the foreign table	or one of its columns.	ADD,
	   SET,	and DROP specify the action to be performed.  ADD is assumed
	   if no operation is explicitly specified. Duplicate option names are
	   not allowed (although it's OK for a table option and	a column
	   option to have the same name). Option names and values are also
	   validated using the foreign data wrapper library.

       RENAME
	   The RENAME forms change the name of a foreign table or the name of
	   an individual column	in a foreign table.

       SET SCHEMA
	   This	form moves the foreign table into another schema.

       All the actions except RENAME and SET SCHEMA can	be combined into a
       list of multiple	alterations to apply in	parallel. For example, it is
       possible	to add several columns and/or alter the	type of	several
       columns in a single command.

       If the command is written as ALTER FOREIGN TABLE	IF EXISTS ...  and the
       foreign table does not exist, no	error is thrown. A notice is issued in
       this case.

       You must	own the	table to use ALTER FOREIGN TABLE. To change the	schema
       of a foreign table, you must also have CREATE privilege on the new
       schema. To alter	the owner, you must be able to SET ROLE	to the new
       owning role, and	that role must have CREATE privilege on	the table's
       schema. (These restrictions enforce that	altering the owner doesn't do
       anything	you couldn't do	by dropping and	recreating the table. However,
       a superuser can alter ownership of any table anyway.) To	add a column
       or alter	a column type, you must	also have USAGE	privilege on the data
       type.

PARAMETERS
       name
	   The name (possibly schema-qualified)	of an existing foreign table
	   to alter. If	ONLY is	specified before the table name, only that
	   table is altered. If	ONLY is	not specified, the table and all its
	   descendant tables (if any) are altered. Optionally, * can be
	   specified after the table name to explicitly	indicate that
	   descendant tables are included.

       column_name
	   Name	of a new or existing column.

       new_column_name
	   New name for	an existing column.

       new_name
	   New name for	the table.

       data_type
	   Data	type of	the new	column,	or new data type for an	existing
	   column.

       table_constraint
	   New table constraint	for the	foreign	table.

       constraint_name
	   Name	of an existing constraint to drop.

       CASCADE
	   Automatically drop objects that depend on the dropped column	or
	   constraint (for example, views referencing the column), and in turn
	   all objects that depend on those objects (see Section 5.15).

       RESTRICT
	   Refuse to drop the column or	constraint if there are	any dependent
	   objects. This is the	default	behavior.

       trigger_name
	   Name	of a single trigger to disable or enable.

       ALL
	   Disable or enable all triggers belonging to the foreign table.
	   (This requires superuser privilege if any of	the triggers are
	   internally generated	triggers. The core system does not add such
	   triggers to foreign tables, but add-on code could do	so.)

       USER
	   Disable or enable all triggers belonging to the foreign table
	   except for internally generated triggers.

       parent_table
	   A parent table to associate or de-associate with this foreign
	   table.

       new_owner
	   The user name of the	new owner of the table.

       new_schema
	   The name of the schema to which the table will be moved.

NOTES
       The key word COLUMN is noise and	can be omitted.

       Consistency with	the foreign server is not checked when a column	is
       added or	removed	with ADD COLUMN	or DROP	COLUMN,	a NOT NULL or CHECK
       constraint is added, or a column	type is	changed	with SET DATA TYPE. It
       is the user's responsibility to ensure that the table definition
       matches the remote side.

       Refer to	CREATE FOREIGN TABLE for a further description of valid
       parameters.

EXAMPLES
       To mark a column	as not-null:

	   ALTER FOREIGN TABLE distributors ALTER COLUMN street	SET NOT	NULL;

       To change options of a foreign table:

	   ALTER FOREIGN TABLE myschema.distributors OPTIONS (ADD opt1 'value',	SET opt2 'value2', DROP	opt3);

COMPATIBILITY
       The forms ADD, DROP, and	SET DATA TYPE conform with the SQL standard.
       The other forms are PostgreSQL extensions of the	SQL standard. Also,
       the ability to specify more than	one manipulation in a single ALTER
       FOREIGN TABLE command is	an extension.

       ALTER FOREIGN TABLE DROP	COLUMN can be used to drop the only column of
       a foreign table,	leaving	a zero-column table. This is an	extension of
       SQL, which disallows zero-column	foreign	tables.

SEE ALSO
       CREATE FOREIGN TABLE (CREATE_FOREIGN_TABLE(7)), DROP FOREIGN TABLE
       (DROP_FOREIGN_TABLE(7))

PostgreSQL 17.5			     2025		ALTER FOREIGN TABLE(7)

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