BUG #11804: The delete rule problem - Mailing list pgsql-bugs

The following bug has been logged on the website:

Bug reference:      11804
Logged by:          Justin Lu
Email address:      djlu126@126.com
PostgreSQL version: 9.3.5
Operating system:   Windows 7 Ultimate x86
Description:

The situation as flowing:

CREATE TABLE test
(
  test_id integer NOT NULL,
  CONSTRAINT test_pkey PRIMARY KEY (test_id)
);

CREATE TABLE details
(
  test_id integer NOT NULL,
  prd_id integer NOT NULL,
  quantity integer,
  CONSTRAINT details_pkey PRIMARY KEY (test_id, prd_id)
);

CREATE TABLE stock
(
  prd_id integer NOT NULL,
  remaining integer,
  CONSTRAINT stock_pkey PRIMARY KEY (prd_id)
);

CREATE OR REPLACE RULE test_d1 AS
    ON DELETE TO test DO  DELETE FROM details
  WHERE details.test_id = old.test_id;

CREATE OR REPLACE RULE details_d1 AS
    ON DELETE TO details
   WHERE (EXISTS ( SELECT stock_1.prd_id
           FROM stock stock_1
          WHERE stock_1.prd_id = old.prd_id)) DO  UPDATE stock SET remaining
= stock.remaining - old.quantity
  WHERE stock.prd_id = old.prd_id;

CREATE OR REPLACE RULE details_d2 AS
    ON DELETE TO details
   WHERE NOT (EXISTS ( SELECT stock_1.prd_id
           FROM stock stock_1
          WHERE stock_1.prd_id = old.prd_id)) DO  INSERT INTO stock (prd_id,
remaining)
  VALUES (old.prd_id, - old.quantity);

COPY stock (prd_id, remaining) FROM stdin;
1    9
2    9
3    9
4    9
5    9
6    9
7    9
8    9
9    9
\.

COPY test (test_id) FROM stdin;
1
2
3
4
5
6
7
8
9
\.

COPY dtls (test_id, prd_id, quantity) FROM stdin;
1    1    1
1    2    1
1    3    1
1    4    1
1    5    1
1    6    1
1    7    1
1    8    1
1    9    1
2    1    1
2    2    1
2    3    1
2    4    1
2    5    1
2    6    1
2    7    1
2    8    1
2    9    1
3    1    1
3    2    1
3    3    1
3    4    1
3    5    1
3    6    1
3    7    1
3    8    1
3    9    1
4    1    1
4    2    1
4    3    1
4    4    1
4    5    1
4    6    1
4    7    1
4    8    1
4    9    1
5    1    1
5    2    1
5    3    1
5    4    1
5    5    1
5    6    1
5    7    1
5    8    1
5    9    1
6    1    1
6    2    1
6    3    1
6    4    1
6    5    1
6    6    1
6    7    1
6    8    1
6    9    1
7    1    1
7    2    1
7    3    1
7    4    1
7    5    1
7    6    1
7    7    1
7    8    1
7    9    1
8    1    1
8    2    1
8    3    1
8    4    1
8    5    1
8    6    1
8    7    1
8    8    1
8    9    1
9    1    1
9    2    1
9    3    1
9    4    1
9    5    1
9    6    1
9    7    1
9    8    1
9    9    1
\.

Then I execute the command:

delete from test where test_id in(1,2);
select * from stock;

The result is:

 prd_id | remaining
--------+-----------
      1 |         8
      2 |         8
      3 |         8
      4 |         8
      5 |         8
      6 |         8
      7 |         8
      8 |         8
      9 |         8

Shouldn't it be:

 prd_id | remaining
--------+-----------
      1 |         7
      2 |         7
      3 |         7
      4 |         7
      5 |         7
      6 |         7
      7 |         7
      8 |         7
      9 |         7
?