Postgres 13

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CREATE TABLE my_table
(
    id           uuid,
    code         VARCHAR(50) PRIMARY KEY,
    value        VARCHAR(50),
    last_updated TIMESTAMP WITH TIME ZONE DEFAULT now()
);


CREATE TABLE


CREATE FUNCTION gen_deterministic_id()
    RETURNS TRIGGER AS
$$
BEGIN
    NEW.id = md5('xx' || NEW.value)::uuid;
    RETURN NEW;
END;
$$ language 'plpgsql';

CREATE FUNCTION


CREATE TRIGGER generate_uuid
  BEFORE INSERT
  ON my_table
  FOR EACH ROW
  EXECUTE PROCEDURE gen_deterministic_id();

CREATE TRIGGER


INSERT INTO my_table (code, value)
VALUES ('a','a'), 
       ('b','b');

INSERT 0 2


SELECT * FROM my_table


id
code
value
last_updated


b03481e8-0c60-bbfc-a842-69bfd7a4df27
a
a
2025-05-31 08:07:09.574872+01

b2b46220-d545-35eb-548c-975f37cdf51b
b
b
2025-05-31 08:07:09.574872+01



SELECT 2

id	code	value	last_updated
b03481e8-0c60-bbfc-a842-69bfd7a4df27	a	a	2025-05-31 08:07:09.574872+01
b2b46220-d545-35eb-548c-975f37cdf51b	b	b	2025-05-31 08:07:09.574872+01