Hi,
I am prototyping a system which sends all INSERT/UPDATE/DELETE events
to a third party software, I do:
CREATE TABLE data (id Serial PRIMARY KEY, data VARCHAR(255));
CREATE TABLE log (op CHAR(6), id integer, data VARCHAR(255));
CREATE OR REPLACE RULE send_notify AS ON INSERT TO log DO ALSO NOTIFY logevent;
CREATE OR REPLACE FUNCTION log_event() RETURNS TRIGGER AS $$
BEGIN
IF (TG_OP = 'DELETE') THEN
INSERT INTO log VALUES ('DELETE', OLD.id, OLD.data);
ELSIF (TG_OP = 'UPDATE') THEN
INSERT INTO log VALUES ('UPDATE', NEW.id, NEW.data);
ELSIF (TG_OP = 'INSERT') THEN
INSERT INTO log VALUES ('INSERT', NEW.id, NEW.data);
END IF;
RETURN NULL;
END;
$$ LANGUAGE plpgsql;
CREATE TRIGGER log_event_trigger AFTER INSERT OR UPDATE OR DELETE ON
data FOR EACH ROW EXECUTE PROCEDURE log_event();
A simple client program is used to wait for the NOTIFY logevent and
query the log table to send the changes, then delete what he has sent.
When I inserted data to TABLE data with the rate of about 25 every
second, the client can receive the notifies without any problem, and
when I use 3 similar programs to feed data, which means about 75
events every second, I found that Postgres didn't send NOTIFY
opportunely, since the client do SELECT query every several hundreds
seconds, which is too long to be acceptable.
So what I want to know is, is there anything wrong with my idea? and
how frequence can LISTEN/NOTIFY support? Thanks.
Regards,
Gavin Mu
