SET client_min_messages=NOTICE;
CREATE EXTENSION multicorn;
create or replace function create_foreign_server() returns void as $block$
  DECLARE
    current_db varchar;
  BEGIN
    SELECT into current_db current_database();
    EXECUTE $$ 
    CREATE server multicorn_srv foreign data wrapper multicorn options (
        wrapper 'multicorn.sqlalchemyfdw.SqlAlchemyFdw',
        db_url 'postgresql://$$ || current_user || '@localhost/' || current_db || $$'
    );
    $$;
  END;
$block$ language plpgsql;
select create_foreign_server();
 create_foreign_server 
-----------------------
 
(1 row)

CREATE SCHEMA local_schema;
CREATE TABLE local_schema.t1 (
  c1 int primary key,
  c2 text,
  c3 timestamp,
  c4 numeric
);
CREATE TABLE local_schema.t2 (
  c1 int,
  c2 text,
  c3 timestamp,
  c4 numeric
);
CREATE TABLE local_schema.t3 (
  c1 int,
  c2 text,
  c3 timestamp,
  c4 numeric
);
CREATE SCHEMA remote_schema;
IMPORT FOREIGN SCHEMA local_schema FROM SERVER multicorn_srv INTO remote_schema ;
\d remote_schema.t1
                Foreign table "remote_schema.t1"
 Column |            Type             | Modifiers | FDW Options 
--------+-----------------------------+-----------+-------------
 c1     | integer                     |           | 
 c2     | text                        |           | 
 c3     | timestamp without time zone |           | 
 c4     | numeric                     |           | 
Server: multicorn_srv
FDW Options: (primary_key 'c1', schema 'local_schema', tablename 't1')

\d remote_schema.t2
                Foreign table "remote_schema.t2"
 Column |            Type             | Modifiers | FDW Options 
--------+-----------------------------+-----------+-------------
 c1     | integer                     |           | 
 c2     | text                        |           | 
 c3     | timestamp without time zone |           | 
 c4     | numeric                     |           | 
Server: multicorn_srv
FDW Options: (schema 'local_schema', tablename 't2')

\d remote_schema.t3
                Foreign table "remote_schema.t3"
 Column |            Type             | Modifiers | FDW Options 
--------+-----------------------------+-----------+-------------
 c1     | integer                     |           | 
 c2     | text                        |           | 
 c3     | timestamp without time zone |           | 
 c4     | numeric                     |           | 
Server: multicorn_srv
FDW Options: (schema 'local_schema', tablename 't3')

SELECT * FROM remote_schema.t1;
 c1 | c2 | c3 | c4 
----+----+----+----
(0 rows)

INSERT INTO remote_schema.t1 VALUES (1, '2', NULL, NULL);
SELECT * FROM remote_schema.t1;
 c1 | c2 | c3 | c4 
----+----+----+----
  1 | 2  |    |   
(1 row)

DROP SCHEMA remote_schema CASCADE;
NOTICE:  drop cascades to 3 other objects
DETAIL:  drop cascades to foreign table remote_schema.t1
drop cascades to foreign table remote_schema.t2
drop cascades to foreign table remote_schema.t3
CREATE SCHEMA remote_schema;
IMPORT FOREIGN SCHEMA local_schema LIMIT TO (t1) FROM SERVER multicorn_srv INTO remote_schema ;
SELECT relname FROM pg_class c INNER JOIN pg_namespace n on c.relnamespace = n.oid WHERE n.nspname = 'remote_schema';
 relname 
---------
 t1
(1 row)

IMPORT FOREIGN SCHEMA local_schema EXCEPT (t1, t3) FROM SERVER multicorn_srv INTO remote_schema ;
SELECT relname FROM pg_class c INNER JOIN pg_namespace n on c.relnamespace = n.oid WHERE n.nspname = 'remote_schema';
 relname 
---------
 t1
 t2
(2 rows)

DROP EXTENSION multicorn CASCADE;
NOTICE:  drop cascades to 3 other objects
DETAIL:  drop cascades to server multicorn_srv
drop cascades to foreign table remote_schema.t1
drop cascades to foreign table remote_schema.t2
DROP SCHEMA local_schema CASCADE;
NOTICE:  drop cascades to 3 other objects
DETAIL:  drop cascades to table local_schema.t1
drop cascades to table local_schema.t2
drop cascades to table local_schema.t3
DROP SCHEMA remote_schema CASCADE;
