Bug: Rule actions see wrong values for generated columns (NEW.gen reads OLD value) - Mailing list pgsql-hackers

for update or NULL for insert cases in a DO ALSO rule action for

generated columns.  This bug affects both stored and virtual 

generated columns. Reporting here to see if this is a known issue

with generated columns.

Repro:

CREATE TABLE t (id int PRIMARY KEY, a int,
                gen int GENERATED ALWAYS AS (a * 2) VIRTUAL);
CREATE TABLE t_log (op text, old_gen int, new_gen int);

CREATE RULE t_log AS ON UPDATE TO t
  DO ALSO INSERT INTO t_log VALUES ('UPD', OLD.gen, NEW.gen);

INSERT INTO t (id, a) VALUES (1, 5); 
UPDATE t SET a = 100 WHERE id = 1; 

postgres=# SELECT * FROM t;
 id |  a  | gen
----+-----+-----
  1 | 100 | 200
(1 row)

postgres=# SELECT * FROM t_log;
 op  | old_gen | new_gen
-----+---------+---------
 UPD |      10 |      10
(1 row)

Thanks,

Satya