Syntax:
UUID_SHORT()

Returns a "short" universal identifier as a 64-bit unsigned integer.
Values returned by UUID_SHORT() differ from the string-format 128-bit
identifiers returned by the UUID() function and have different
uniqueness properties. The value of UUID_SHORT() is guaranteed to be
unique if the following conditions hold:

o The server_id value of the current server is between 0 and 255 and is
  unique among your set of source and replica servers

o You do not set back the system time for your server host between
  mysqld restarts

o You invoke UUID_SHORT() on average fewer than 16 million times per
  second between mysqld restarts

The UUID_SHORT() return value is constructed this way:

  (server_id & 255) << 56
+ (server_startup_time_in_seconds << 24)
+ incremented_variable++;

URL: https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html

