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 }
           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 WITH OIDS
           SET WITHOUT OIDS
           INHERIT parent_table
           NO INHERIT parent_table
           OWNER TO { new_owner | 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 (CREATE_FOREIGN_TABLE(7)). 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(7)
           operations. See the similar form of ALTER TABLE (ALTER_TABLE(7)) 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
           (ALTER_TABLE(7)) for more details.

       SET STORAGE
           This form sets the storage mode for a column. See the similar form of ALTER TABLE
           (ALTER_TABLE(7)) 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 (CREATE_FOREIGN_TABLE(7)). 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 (CREATE_FOREIGN_TABLE(7)).) 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 (ALTER_TABLE(7)) for more details.

       SET WITH OIDS
           This form adds an oid system column to the table (see Section 5.4). It does nothing if
           the table already has OIDs. Unless the table's foreign-data wrapper supports OIDs,
           this column will simply read as zeroes.

           Note that this is not equivalent to ADD COLUMN oid oid; that would add a normal column
           that happened to be named oid, not a system column.

       SET WITHOUT OIDS
           This form removes the oid system column from the table. This is exactly equivalent to
           DROP COLUMN oid RESTRICT, except that it will not complain if there is already no oid
           column.

       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 (ALTER_TABLE(7)) 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
       also be a direct or indirect member of 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 5.13).

       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 (CREATE_FOREIGN_TABLE(7)) 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 'value3');

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))