clcarter wrote:This mean to me: the database queries date/time only on database-startup, a time drift would not detected by the database.
The database sysdate and systimestamp calls the OS time routines to get the current time from the host clock.
Try removing the CMOS battery from the machine, unplug it from AC power ... wait an hour or two and see what happens.
If system time is not in sync with "clock time", sysdate won't have the correct time either. ntp (Network Time Protocol) will slew the system clock until it matches, see http://en.wikipedia.org/wiki/Network_Time_Protocol
And of course, if the host ntp daemon is not running system time can drift and vary quite a bit from "true" time.