The following bug has been logged online:

Bug reference: 1781
Logged by: Andrew Smith
Email address: andrew (AT) asmith (DOT) id.au
PostgreSQL version: 7.4.6
Operating system: Debian GNU/Linux 3.1
Description: result of cascading triggers not available until
function exits.
Details:

CREATE TABLE master(value INTEGER);
CREATE TABLE detail(value INTEGER,parent INTEGER);

CREATE FUNCTION aftermaster() RETURNS TRIGGER AS '
BEGIN
INSERT INTO detail(value,parent)
VALUES(10,NEW.value);
INSERT INTO detail(value,parent)
VALUES(20,NEW.value);
RETURN NULL;
END;
' LANGUAGE plpgsql;

CREATE TRIGGER aftermaster AFTER INSERT OR UPDATE ON master
FOR EACH ROW EXECUTE PROCEDURE aftermaster();

CREATE OR REPLACE FUNCTION dostuff() RETURNS VOID AS '
DECLARE
counter INTEGER;
BEGIN
INSERT INTO master(value) VALUES(1);
SELECT COUNT(*) INTO counter FROM detail;
RAISE NOTICE ''counter = %'',counter;
RETURN NULL;
END
' LANGUAGE plpgsql;

/*
on PostgreSQL 8.0 log output is 'counter = 2'
but for version 7.4.6 log output is 'counter = 0'
*/

SELECT dostuff();
SELECT COUNT(*) FROM detail;

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TIP 2: Don't 'kill -9' the postmaster