The UUID_SHORT() function returns a "short" Universally Unique Identifier as a 64-bit unsigned integer.
The value of UUID_SHORT() is guaranteed to be unique if the following conditions are met:
The server ID of the current host is unique among your master and slave servers and ranges from 0 to 255.
The system time for the server was not reset after restarting mysqld.
Since mysqld restarts, the UUID_SHORT() function is being called no more than 16 million times per second on average.