Re: Best way to restrict detail rows?

On Mon, Dec 8, 2008 at 1:28 PM, Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com> wrote:
> On Mon, Dec 8, 2008 at 1:56 PM, Christopher Maier <maier(at)med(dot)unc(dot)edu> wrote:
>> I have a "master-detail" kind of situation, as illustrated here:
>>
>> CREATE TABLE master(
>> id SERIAL PRIMARY KEY,
>> foo TEXT
>> );
>>
>> CREATE TABLE detail(
>> id SERIAL PRIMARY KEY
>> master BIGINT NOT NULL REFERENCES master(id),
>> bar TEXT
>> );
>>
>> (this is a simplification, of course)
>>
>> I would like a way to restrict the addition of new detail records, but only
>> after the initial detail records have been inserted into the system.
>
> After you create the table do something like this:
>
> create rule detail_no_insert as on insert to detail do nothing;
> create rule detail_no_update as on update to detail do nothing;
>
> poof. no more updates or inserts work. Note that copy will still
> work, as it doesn't fire rules. So, you can update the data with
> copy, and otherwise not touch it.

One Idea that popped into my head that may-or-may-not work would be to
add a constraint trigger that checks if all of the detail records have
the same xmin as the order table record.

--
Regards,
Richard Broersma Jr.

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