On 03/05/11 11:07, Greg Smith wrote: > That doesn't mean you can't use > them as a sort of foreign key indexing the data; it just means you can't > make them the sole unique identifier for a particular entity, where that > entity is a person, company, or part. Classic case: a database here has several tables indexed by MAC address. It's used for asset reporting and software inventory. Problem: VMs generate random MAC addresses by default. They're not guaranteed to be globally unique. Collisions have happened and will probably happen again. In this case, it wasn't a big deal, but it just goes to show that even the "obviously" globally unique isn't necessarily so. -- Craig Ringer -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
