Re: Table rewrites vs. pending AFTER triggers

Tom Lane wrote:
> Alvaro Herrera <alvherre@commandprompt.com> writes:
>   
>>> On Tue, 2008-01-01 at 16:09 -0500, Tom Lane wrote:
>>>       
>>>> Paranoia would
>>>> suggest forbidding *any* form of ALTER TABLE when there are pending
>>>> trigger events, but maybe that's unnecessarily strong.
>>>>         
>
>   
>> I disagree.  This is an implementation limitation, so it makes sense to
>> try to restrict the user as least as possible.
>>     
>
> There's a tradeoff here between security, flexibility, and the amount of
> work we want to put into it.  At the moment it's not clear to me that
> it's worth spending the amount of work that would be needed to determine
> which forms of ALTER TABLE are "safe" in this connection.  If you're
> feeling hot about it, feel free to do the legwork.
>
> (A precedent is that all forms of ALTER TABLE take exclusive lock,
> which is more or less the same thing for the cross-backend case.
> There's been occasional discussion of whether some forms could
> take lesser locks, but never enough interest to make it happen.)
>
>     
>   

I'd still like to see a sane use case. The other thing being traded off 
is possibly simplicity.

cheers

andrew