title: OrientDB collision probability on UNIQUE_HASH_INDEX?
body: <p>My code assigns UUIDv4 IDs for various entities (e.g. user accounts) in my system. While UUIDv4 is pretty much considered guaranteed unique, I'd rather be 100%, and as such, I've created an index of type UNIQUE_HASH_INDEX in my OrientDB instance.</p>
  
  <p>However, I realized that the hash generated by OrientDB might be of a smaller size than my UUIDv4 value (128 bits), and I might get collision errors although the IDs are actually different.</p>
  
  <p>I am not very familiar with the underlying hash algorithm used in OrientDB, and I was wondering if anyone can point out if whether or not it will be a possibility for me to get false positive collisions on my UNIQUE constraint?</p>