>>> date ones are a problem if more that one has to be allocated in the
>>> same tick.
>> The obvious solution there is to use a counter that's initialized
>> from the clock at reboot time.  We can't reboot in less than a
>> tick...
>
>No, but if more than one xid per tick is needed over the long term, the
>xids will get ahead of the clock, and then on reboot it will start
>reusing xids that were used recently.

	and if you adjust time to backwards by date(1) you are hosed.

itojun