Isso pode funcionar em vez do seu gatilho:
CREATE MATERIALIZED VIEW mv_my
BUILD IMMEDIATE
REFRESH FAST ON COMMIT AS
SELECT POSTALCODE, COUNT(*) AS cnt FROM TEST GROUP BY POSTALCODE
/
ALTER TABLE mv_my ADD CHECK(cnt < 2)
/
Deixe-me saber.
Sebas
CREATE MATERIALIZED VIEW mv_my
BUILD IMMEDIATE
REFRESH FAST ON COMMIT AS
SELECT POSTALCODE, COUNT(*) AS cnt FROM TEST GROUP BY POSTALCODE
/
ALTER TABLE mv_my ADD CHECK(cnt < 2)
/
