| From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Chris Browne <cbbrowne(at)acm(dot)org>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: ALTER TABLE ... ADD FOREIGN KEY ... NOT ENFORCED |
| Date: | 2011-01-23 22:10:43 |
| Message-ID: | 1295820643.1803.20556.camel@ebony |
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| Lists: | pgsql-hackers |
On Sun, 2011-01-23 at 16:13 -0500, Tom Lane wrote:
> Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
> > You can add an FK without an initial check, but the FK is enforced for
> > all further DML changes.
>
> I seem to recall pointing out upthread that the FK check triggers are
> designed on the assumption that the constraint does hold currently.
> Has any analysis been done on exactly how badly they'll fail when it
> doesn't hold? I remain unconvinced that this behavior is desirable.
If you mean RESTRICT relationships, then yes.
I haven't foreseen other problems myself. What other ideas or risks
would you like me to confirm or deny for you?
--
Simon Riggs http://www.2ndQuadrant.com/books/
PostgreSQL Development, 24x7 Support, Training and Services
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