CREATE TABLE product (
  doc_id INT,
  details JSONB
);


INSERT INTO product VALUES (1, '{"CPU":4, "RAM":16, "HDD":2}');
INSERT INTO product VALUES (2, '{"CPU":3, "RAM":8, "HDD":1}');


doc_id |             details             
----+---------------------------------
  1 | {"CPU": 4, "HDD": 2, "RAM": 16}
  2 | {"CPU": 3, "HDD": 1, "RAM": 8}

CREATE TABLE replace (
  id INT,
  doc_id INT,
  old_key text,
  new_key text
);
INSERT INTO replace VALUES (1, 1, 'CPU', 'RAM');
INSERT INTO replace VALUES (2, 1, 'HDD', 'SSD');
INSERT INTO replace VALUES (3, 2, 'HDD', 'SSD');

id | doc_id | old_key | new_key 
----+--------+---------+---------
  1 |      1 | CPU     | RAM
  2 |      1 | HDD     | SSD
  3 |      2 | HDD     | SSD

id |             details             
----+---------------------------------
  1 | {"SSD": 2, "RAM": 20}
  2 | {"CPU": 3, "SSD": 1, "RAM": 8}