remote db procedures/functions

Hi guys

For a project which involves auditing changes in the db, I am looking at storing the changes on a different server .

So I looked at writing an audit trigger .

If all would be locally I would have gone on something like


CREATE OR REPLACE FUNCTION process_emp_audit() RETURNS TRIGGER AS $emp_audit$
    BEGIN
        --
        -- Create a row in emp_audit to reflect the operation performed on emp,
        -- make use of the special variable TG_OP to work out the operation.
        --
        IF (TG_OP = 'DELETE') THEN
            INSERT INTO emp_audit SELECT 'D', now(), user, OLD.*;
            RETURN OLD;
        ELSIF (TG_OP = 'UPDATE') THEN
            INSERT INTO emp_audit SELECT 'U', now(), user, OLD.*;
            RETURN NEW;
        END IF;
        RETURN NULL; -- result is ignored since this is an AFTER trigger
    END;
$emp_audit$ LANGUAGE plpgsql;

CREATE TRIGGER emp_audit
AFTER INSERT OR UPDATE OR DELETE ON emp
    FOR EACH ROW EXECUTE PROCEDURE process_emp_audit();


Given the need I looked at plproxy and dblink


In plproxy I got

CREATE OR REPLACE FUNCTION log_emp_audit( operation text, userid text, empname text, salary integer ) RETURNS VOID AS
$$
CONNECT 'dbname=auditdb';
$$ LANGUAGE plproxy;

CREATE OR REPLACE FUNCTION do_emp_audit() RETURNS TRIGGER AS $$
BEGIN
IF (TG_OP = 'DELETE') THEN
PERFORM log_emp_audit('DEL', user, OLD.empname, OLD.salary);
ELSIF (TG_OP = 'UPDATE') THEN
-- save old and new values
PERFORM log_emp_audit('OLD', user, OLD.empname, OLD.salary);
PERFORM log_emp_audit('NEW', user, NEW.empname, NEW.salary);
ELSIF (TG_OP = 'INSERT') THEN
PERFORM log_emp_audit('INS', user, NEW.empname, NEW.salary);
END IF;
RETURN NULL;
-- result is ignored since this is an AFTER trigger
END;
$$ LANGUAGE plpgsql;

CREATE TRIGGER emp_remote_audit
AFTER INSERT OR UPDATE OR DELETE ON emp
FOR EACH ROW EXECUTE PROCEDURE do_emp_audit();


Now on dblink I tried like in all local version


CREATE OR REPLACE FUNCTION process_emp_audit() RETURNS TRIGGER AS $emp_audit$
    BEGIN
        IF (TG_OP = 'DELETE') THEN
            PERFORM dblink_connect('dbname=mydb2 port=5432 user=postgres password=hd883XLC');
        PERFORM dblink_exec('INSERT INTO emp_audit SELECT ''D'', now(), user, ''OLD.*''');
            RETURN OLD;
        ELSIF (TG_OP = 'UPDATE') THEN
            PERFORM dblink_connect('dbname=mydb2 port=5432 user=postgres password=hd883XLC');
            PERFORM dblink_exec('INSERT INTO emp_audit SELECT ''U'', now(), user, ''OLD.*''');
            RETURN NEW;
        END IF;
        RETURN NULL; -- result is ignored since this is an AFTER trigger
    END;
$emp_audit$ LANGUAGE plpgsql;


CREATE TRIGGER emp_audit
AFTER INSERT OR UPDATE OR DELETE ON emp
    FOR EACH ROW EXECUTE PROCEDURE process_emp_audit();



I did noticed in the research I did that in plproxy each column value was specified , i.e. old.salary etc etc , as
opposedto the local version in which I could use old.* 

1 - Can I use the same old.* in plproxy and dblink ? If so how ?
2 - If (1) is false, am I correct to assume that the only way I could achieve my goal using dblink/plproxy would be
specifyingeach column individually , i.e. old. salary etc etc ?  

I am inclined to believe (2) is the way and to some extend might fit better since I can filter what columns I will use

Thank you for help


Armand