auth_users_trigger.sql

-- trigger function is created here (not the actual trigger).
CREATE OR REPLACE FUNCTION insert_into_public_users()
RETURNS TRIGGER AS $$
  BEGIN
    INSERT INTO public.users (id, email, created_at)
    VALUES(NEW.id, NEW.email, NOW());

    RETURN NEW;
  END;
$$
LANGUAGE plpgsql SECURITY DEFINER;

-- defining a trigger on the auth.users table.
-- calls the insert_into_public_users() trigger function for every row that is inserted into auth.users.
CREATE TRIGGER on_signup
AFTER INSERT ON auth.users
FOR EACH ROW EXECUTE PROCEDURE insert_into_public_users();