Обсуждение: BUG #17247: How to avoid crating multiple Foreign keys on same column on same table.

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BUG #17247: How to avoid crating multiple Foreign keys on same column on same table.

От
PG Bug reporting form
Дата:
The following bug has been logged on the website:

Bug reference:      17247
Logged by:          bipsy Nair
Email address:      nbipin29@gmail.com
PostgreSQL version: 13.4
Operating system:   Any OS
Description:

Issue: Postgres engine allows multiple FK on same columns for a same
table.This cause duplication and unwanted use of space . If we accidentally
run a script multiple times it creates the FK mulitple times. 
Ran the following statement 3 times : to add a foreign key
ALTER TABLE admin.emp
ADD FOREIGN KEY (deptno) 
REFERENCES admin.dept (deptno)
ON DELETE NO ACTION;

I see 3 its created thrice . In Oracle this statement should fail. Is there
any way this restriction can be applied on PG. 
admin    emp_deptno_fkey    emp    deptno    admin    dept    deptno
admin    emp_deptno_fkey1    emp    deptno    admin    dept    deptno
admin    emp_deptno_fkey2    emp    deptno    admin    dept    deptno

Please advice.

Re: BUG #17247: How to avoid crating multiple Foreign keys on same column on same table.

От
Juan José Santamaría Flecha
Дата:

On Tue, Oct 26, 2021 at 9:07 AM PG Bug reporting form <noreply@postgresql.org> wrote:

Issue: Postgres engine allows multiple FK on same columns for a same
table.This cause duplication and unwanted use of space . If we accidentally
run a script multiple times it creates the FK mulitple times.
Ran the following statement 3 times : to add a foreign key
ALTER TABLE admin.emp
ADD FOREIGN KEY (deptno)
REFERENCES admin.dept (deptno)
ON DELETE NO ACTION;

I see 3 its created thrice . In Oracle this statement should fail. Is there
any way this restriction can be applied on PG.
admin   emp_deptno_fkey emp     deptno  admin   dept    deptno
admin   emp_deptno_fkey1        emp     deptno  admin   dept    deptno
admin   emp_deptno_fkey2        emp     deptno  admin   dept    deptno

Please advice.

Using a named constraint can prevent this:

ALTER TABLE admin.emp ADD CONSTRAINT emp_deptno_fkey FOREIGN KEY (deptno) REFERENCES admin.dept (deptno) ON DELETE NO ACTION;

Regards,

Juan José Santamaría Flecha