class ActiveRecord::FixtureSet

def identify(label, column_type = :integer)

Integer identifiers are values less than 2^30. UUIDs are RFC 4122 version 5 SHA-1 hashes.
Returns a consistent, platform-independent identifier for +label+. 
def identify(label, column_type = :integer)
  if column_type == :uuid
    Digest::UUID.uuid_v5(Digest::UUID::OID_NAMESPACE, label.to_s)
  else
    Zlib.crc32(label.to_s) % MAX_ID
  end
end