Re: Inserting into foreign table with sequences and default values

Thanks Tom,
Your reply helped point me in the right direction. With a little trial and error I came up with a hack to solve my issue.

First off, I create a shared sequence for the user_id with a technique described here:
[ https://paquier.xyz/postgresql-2/global-sequences-with-postgres_fdw-and-postgres-core/ ]( https://paquier.xyz/postgresql-2/global-sequences-with-postgres_fdw-and-postgres-core/ )

This involved creating a sequence on the remote server and a view of the sequence on the remote server. I also updated the "test" table on the remote server to populate the "id" column using a the sequence via a trigger.

On the local server, I created a foreign table that references the view on the remote server and a function that returns a sequence value from the foreign table.

Finally, on the local server I created a trigger on the remote "test" table that was imported earlier via the "IMPORT FOREIGN SCHEMA" command.

It's all a little hacky but it works :-)

Full steps below for anyone that's interested (sorry if it gets mangled via email).

Thanks Again,
Peter


--------------------
On Remote:
--------------------

CREATE SEQUENCE user_id;

CREATE VIEW user_id_view AS SELECT nextval('user_id') as a;

CREATE FUNCTION user_id_nextval() RETURNS bigint AS
'SELECT a FROM user_id_view;' LANGUAGE SQL;

CREATE TABLE APP.TEST (
ID bigint NOT NULL,
FIRST_NAME text,
LAST_NAME text,
STATUS integer NOT NULL DEFAULT 1,
CONSTRAINT PK_USER PRIMARY KEY (ID)
);

CREATE OR REPLACE FUNCTION test_function()
RETURNS "trigger" AS
$BODY$
BEGIN
New.id := case when New.id IS NULL then user_id_nextval() else New.id end;
New.status := case when New.status IS NULL then 1 else New.status end;
Return NEW;
END;
$BODY$
LANGUAGE 'plpgsql' VOLATILE;

CREATE TRIGGER test_trigger
BEFORE INSERT
ON app.test
FOR EACH ROW
EXECUTE PROCEDURE test_function();

--------------------
On Local
--------------------

CREATE FOREIGN TABLE user_id_foreign_table (a bigint)
SERVER culmen OPTIONS (table_name 'user_id_view');

CREATE FUNCTION user_id_nextval() RETURNS bigint AS
'SELECT a FROM user_id_foreign_table;' LANGUAGE SQL;

IMPORT FOREIGN SCHEMA APP LIMIT TO (TEST)
FROM SERVER culmen INTO public;

CREATE OR REPLACE FUNCTION test_function()
RETURNS "trigger" AS
$BODY$
BEGIN
New.id := case when New.id IS NULL then user_id_nextval() else New.id end;
New.status := case when New.status IS NULL then 1 else New.status end;
Return NEW;
END;
$BODY$
LANGUAGE 'plpgsql' VOLATILE;

CREATE TRIGGER test_trigger
BEFORE INSERT
ON test
FOR EACH ROW
EXECUTE PROCEDURE test_function();

INSERT INTO test(first_name) VALUES ('Bob');