From: Kristjan Tammekivi <kristjantammekivi@gmail.com> Sent: Freitag, 4. Januar 2019 11:46 To: pgsql-general@postgresql.org Subject: Potentially undocumented behaviour change in Postgres 11 concerning OLD record in an after insert trigger
Hi,
I've noticed a change in the behaviour in triggers / hstores in Postgres 11.1 when compared to Postgres 10.5.
The following won't work on Postgres 10.5 but in Postgres 11.1 it works just fine:
CREATE EXTENSION hstore;
CREATE TABLE _tmp_test1 (id serial PRIMARY KEY, val INTEGER); CREATE TABLE _tmp_test1_changes (id INTEGER, changes HSTORE);
CREATE FUNCTION test1_trigger () RETURNS TRIGGER LANGUAGE plpgsql AS $BODY$ BEGIN INSERT INTO _tmp_test1_changes (id, changes) VALUES (NEW.id, hstore(OLD) - hstore(NEW)); RETURN NEW; END $BODY$;
CREATE TRIGGER table_update AFTER INSERT OR UPDATE ON _tmp_test1 FOR EACH ROW EXECUTE PROCEDURE test1_trigger();
INSERT INTO _tmp_test1 (val) VALUES (5);
ERROR: record "old" is not assigned yet
DETAIL: The tuple structure of a not-yet-assigned record is indeterminate.
I doubt that this works on any PG version for INSERT.
According to the documentation:
https://www.postgresql.org/docs/10/plpgsql-trigger.html and https://www.postgresql.org/docs/11/plpgsql-trigger.html
OLD: Data type RECORD; variable holding the old database row for UPDATE/DELETE operations in row-level triggers. This variable is unassigned in statement-level triggers and for INSERT operations.
