Extract a timestamp from a UUID created by Hibernate's uuid.hex function.

extract_timestamp_from_hibernate_uuid.rb

def extract_timestamp_from_hibernate_uuid(str)
  Time.at(str[16,12].to_i(16) / 1000)
end

extract_timestamp_from_hibernate_uuid.sql

/*
 * uuid.hex creates a string of length 32. By default, the UUID it creates 
 * uses "" as a separator, so I'm not sure the exact format of the string, 
 * but it ends up bein something like this:
 *   XXXX-XXXX-XXXX-XXXX-YYYYYYYYYYYY-XXXX
 *
 * where YYYYYYYYYYYY is hexidecimal for the unix time.
 * 
 * Since the UUID is probably in your DB, SQL is a good choice for extracting the timestamp.
 */
select 
  FROM_UNIXTIME(
    CONV(
      SUBSTR(
        '8a10a2e5458d3a63014596e3d525020c',
        17,
        12),
      16, 10) /1000, 
    '%Y-%m-%d %h:%i:%s'
  );