On Jun 7, 2007, at 3:32 AM, Andrus Adamchik wrote:
>> I'm kind of curious if Cayenne supports PK-less for read-only data
>> now, though. Seems to me that could be a useful thing.
>
> It doesn't - otherwise you won't be able to build a valid ObjectId
> and hence - ensure uniqueness across the context.
>
> The only way we can potentially support it is by supporting
> "disconnected" objects, i.e. objects that are fetched from DB, but
> not registered in the ObjectContext. Such objects will only be
> marginally more useful than DataRows though. (IIRC JPA supports
> disconnected objects, produced in some other unrelated scenarios).
JPA supports disconnected objects, that were once retrieved from (or
persisted in) the database. It doesn't support disconnected objects
without a database identity.
Craig
>
> Andrus
>
>
> On Jun 6, 2007, at 7:42 PM, Michael Gentry wrote:
>> It's not a hijacking. It is interesting to point out that JPA
>> does not
>> support tables without PKs -- I really should learn more about JPA
>> soon. I
>> can understand why, too (need to know what to update and how to
>> make joins,
>> etc). I'm kind of curious if Cayenne supports PK-less for read-
>> only data
>> now, though. Seems to me that could be a useful thing.
>>
>> /dev/mrg
>>
>>
>> On 6/6/07, Craig L Russell <Craig.Russel..un.com> wrote:
>>>
>>> I don't want to hijack this thread, but just point out that JPA does
>>> not support tables without primary key; JDO does (including updates)
>>> as an optional feature.
>>>
>>> Craig
>>>
>>>
>
Craig Russell
Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
408 276-5638 mailto:Craig.Russel..un.com
P.S. A good JDO? O, Gasp!
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