[db-wg] Clean up of unreferenced person/role objects

Shane Kerr wrote:
> All,
>
> On Wed, Apr 18, 2007 at 01:34:54PM +0200, Denis Walker wrote:
>   
>> The worst problem that can occur is that someone will enter a
>> reference to their person/role object just as we delete it. However,
>> as we are only deleting unreferenced person/role objects, the time
>> needed to re-create them is minimal. We suspect that a very large
>> proportion of the unreferenced person/role objects that we will be
>> deleting are abandoned objects that are no longer used.
>>     
>
> A bit of thinking can come up with some scenerios that might be
> worse(*).
>
> I definitely think any minor problems are more than outweighed by the
> removal of unused personal data! 
>
> --
> Shane
>
> (*) For example, a worse problem would be referencing the wrong
> person/role object. This can happen like so:
>
> - Person object X created
> - Months pass...
> - Person object X deleted by this process
> - Person object Y created with same "nic-hdl:" as object X
> - User who created person object X decides to use it, but actually
>   refers to object Y (since it has the same "nic-hdl:")
>
> The user who created person object X assumes it is still fine, because
> the usual notification was not received, and in any case it was
> probably protected by "mnt-by:".
>
> Of course, this is an unlikely corner case. :)
>   

This case can already occur:

- Person A creates object X without "mnt-by:"
- Months pass...
- Person B thinks he creates object Y with same "nic-hdl:" as object X
- Person B actually modifies object X and changes it into object Y
- Person A who created person object X decides to use it, but actually
  refers to object Y (since it has the same "nic-hdl:")

Person A who created person object X assumes it is still fine, because
he did not maintain his data and did not include a "notify:" attribute.

This is also an unlikely corner case, but the first part does occasionally happen.

denis