Re: partial "on-delete set null" constraint

W dniu 03.01.2015 o 16:48, Alban Hertroys pisze:
>> On 03 Jan 2015, at 15:20, Rafal Pietrak <rafal@ztk-rp.eu> wrote:
>>
[-------------------------]
>> Yes. This is precisely the "semantics" I'm trying to put into the schema: after a username is "released" from
service,all it's messages become "from unknown user".... unless thoroughly investigated :) 
> It also makes a foreign key reference unusable: There is no unique parent record to match it to, so what exactly are
youreferencing? 

Nothing.

That's precisely my point here. I'd like to have "objects" in mailboxes
table left "hanging around" after it's "disconnected" from service. FK
acting like a power cord of a vacuum cleaner: when in service: hooked
into the wall; after that vacuum cleaner stays there, only disconnected
(and the socket can be used by others).

But pondering the idea as the discussion goes, I think I'll try to use
VIEW query rewriting capabilities, to get the "SET username=NULL; then
DELETE" sequence encoded as an on delete rule of a view created on top
of mailusers table.

-R