the real question is - if you want the email to be unique, why use "surrogate" primary key as UUID.
I wonder what UUID gives you at all? If you want to have non email primary key, why not use md5(email) ? On Wed, May 7, 2014 at 2:19 AM, Tyler Hobbs <ty...@datastax.com> wrote: > > On Mon, May 5, 2014 at 10:27 AM, Ignacio Martin <natx...@gmail.com> wrote: > >> >> When a user registers, the server generates a UUID and performs an INSERT >> ... IF NOT EXISTS into the email_to_UUID table. Immediately after, perform >> a SELECT from the same table and see if the read UUID is the same that the >> one we just generated. If it is, we are allowed to INSERT the data in the >> user table, knowing that no other will be doing it. >> > > INSERT ... IF NOT EXISTS is the correct thing to do here, but you don't > need to SELECT afterwards. If the row does exist, the query results will > show that the insert was not applied and the existing row will be returned. > > > -- > Tyler Hobbs > DataStax <http://datastax.com/> >
