NAME

       ALTER_FOREIGN_TABLE - change the definition of a foreign table

SYNOPSIS

       ALTER FOREIGN TABLE [ IF EXISTS ] name
           action [, ... ]
       ALTER FOREIGN TABLE [ IF EXISTS ] 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
           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 OPTIONS ( [ ADD | SET | DROP ] option ['value'] [, ... ])
           OWNER TO new_owner
           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.

       IF EXISTS
           Do not throw an error if the foreign table does not exist. A notice is issued in this
           case.

       SET DATA TYPE
           This form changes the type of a column of a foreign table.

       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.

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

       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.

       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.

       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.

       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.

       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.

       CASCADE
           Automatically drop objects that depend on the dropped column (for example, views
           referencing the column).

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

       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 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.