INFINITE RECURSION with rules...
Hi to everyone.
I've got some problem with rules.
-- I have 2 tables
CREATE TABLE a (email varchar(20), name varchar(10), num1 smallint, num2
smallint, PRIMARY KEY (email, name));
CREATE TABLE b (id smallint PRIMARY KEY, email_a varchar(20), name_a
varchar(10), tot smallint, FOREIGN KEY (email_a, name_a) REFERENCES
a(email, name));
/*
*My goal is to calculate and insert automatically the value of "tot"
when I insert a row into table b.*
*/
-- Some samples
INSERT INTO a VALUES ('mail1@email.com
<mailto:%27mail1@email.com>','bill',3,5);
INSERT INTO a VALUES ('2mail@email.com
<mailto:%272mail@email.com>','paul',4,7); <mailto:%27mail1@email.com>
-- Then I created a simple function
CREATE OR REPLACE FUNCTION calc(varchar(10), varchar(20)) RETURNS
smallint AS $$
DECLARE
rowww a%ROWTYPE;
BEGIN
SELECT * INTO rowww FROM a WHERE email = $1 AND name = $2;
IF FOUND
THEN RETURN rowww.num1 * rowww.num2;
ELSE
RAISE WARNING 'Error: values non found!';
END IF;
END;
$$ LANGUAGE plpgsql;
-- And this easy rule
CREATE RULE rrr_a_b AS ON INSERT TO b
DO INSTEAD
INSERT INTO b VALUES
(NEW.id,
NEW.email_a,
NEW.name_a,
(SELECT calc(NEW.email_a, NEW.name_a))
);
-- Sample for insert into b
INSERT INTO b VALUES (33,'mail1@email.com','bill');
Trying to insert into b (and using the new rule defined by myself, i
receive this message:
/*ERROR: infinite recursion detected in rules for relation "b"*/
How I could solve this problem?
On Sun, Mar 23, 2008 at 10:30 AM, srdjan <srdjan.matic@anche.no> wrote:
[...]
CREATE TABLE b (id smallint PRIMARY KEY, email_a varchar(20), name_a
varchar(10), tot smallint, FOREIGN KEY (email_a, name_a) REFERENCES a(email,
name));
[...]
-- And this easy rule
CREATE RULE rrr_a_b AS ON INSERT TO b
DO INSTEAD
INSERT INTO b VALUES
(NEW.id,
NEW.email_a,
NEW.name_a,
(SELECT calc(NEW.email_a, NEW.name_a))
);-- Sample for insert into b
INSERT INTO b VALUES (33,'mail1@email.com','bill');
[...]
Trying to insert into b (and using the new rule defined by myself, i receive
this message:ERROR: infinite recursion detected in rules for relation "b"
when you insert into b the rule rewrites your query into an insert
into b... ah... another insert into b, the rule rewrites *again* the
query into (guess what?) another insert into b... and the rule system
will continue rewriting your query until it get something different to
an insert into b... hope i was clear...
now, why the rule? isn't enough to simply do this?
INSERT INTO b VALUES (33,'mail1@email.com','bill',
calc('mail1@email.com', 'bill'));
or maybe using a trigger before insert but you're insert should look like:
INSERT INTO b(id, email_a, name_a) VALUES (33,'mail1@email.com','bill');
and in the trigger fill the tot column
--
regards,
Jaime Casanova
srdjan wrote:
/*
*My goal is to calculate and insert automatically the value of "tot"
when I insert a row into table b.*
*/
Use a trigger. It's a lot simpler.
--
Alvaro Herrera http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support