New UUID Formats
I used to be a big proponent of using UUIDs for database PKs but I've found them inherently difficult to work with.  It's much easier to remember/recognize an integer based PK when troubleshooting a data problem.<p>This isn't to say you shouldn't use UUIDs at all, but I much prefer to use an "ExternalId" column of UUID type if you don't want to expose your integer based PKs externally.