On Aug 20, 2013, at 2:33 PM, Chris Behrens <cbehr...@codestud.com> wrote:
> For instances table, we want to make sure 'uuid' is unique. But we can't put > a unique constraint on that alone. If that instance gets deleted.. we should > be able to create another entry with the same uuid without a problem. So we > need a unique constraint on uuid+deleted. But if 'deleted' is only 0 or 1… > we can only have 1 entry deleted and 1 entry not deleted. Using deleted=`id` > to mark deletion solves that problem. You could use deleted_at… but 2 > creates and deletes within the same second would not work. :) This creates another problem if you ever need to delete this second instance, because now you have two with the same uuid and the same deleted status. 'deleted_at' is slightly better, as the only place it would fail is if all of this happened within the same unit of precision for that time value. -- Ed Leafe _______________________________________________ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
