ON DELETE SET NULL clauses do error when more than two columns are referenced to one table - Mailing list pgsql-bugs

From Pavel Stehule
Subject ON DELETE SET NULL clauses do error when more than two columns are referenced to one table
Date
Msg-id 162867790708111100x3775c51bi53dbecabb97d14b7@mail.gmail.com
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Responses Re: ON DELETE SET NULL clauses do error when more than two columns are referenced to one table
List pgsql-bugs
Hello

One question on www.abclinuxu.cz signalise bug in PostgreSQL RI
implementation. Detected on 8.0.x and verified on 8.3.

Regards
Pavel Stehule

CREATE TABLE users (
 id integer NOT NULL,
 name VARCHAR NOT NULL,
 PRIMARY KEY (id)
);

INSERT INTO users VALUES (1, 'Jozko');
INSERT INTO users VALUES (2, 'Ferko');
INSERT INTO users VALUES (3, 'Samko');

CREATE TABLE tasks (
 id integer NOT NULL,
 owner INT REFERENCES  users (id) ON UPDATE CASCADE ON DELETE SET NULL,
 worker INT REFERENCES users (id) ON UPDATE CASCADE ON DELETE SET NULL,
 checked_by INT REFERENCES users (id) ON UPDATE CASCADE ON DELETE SET NULL,
 PRIMARY KEY (id)
);
INSERT INTO tasks VALUES (1,1,NULL,NULL);
INSERT INTO tasks VALUES (2,2,2,NULL);
INSERT INTO tasks VALUES (3,3,3,3);

DELETE FROM users WHERE id = 1; -- works simple
DELETE FROM users WHERE id = 2; -- works ok
DELETE FROM users WHERE id = 3; -- doesn't work, why?

ERROR:  insert or update on table "tasks" violates foreign key
constraint "tasks_checked_by_fkey"
DETAIL:  Key (checked_by)=(3) is not present in table "users".
CONTEXT:  SQL statement "UPDATE ONLY "public"."tasks" SET "worker" =
NULL WHERE $1 OPERATOR(pg_catalog.=) "worker""

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