Re: What does PostgreSQL do when time goes backward?

John Hasler wrote:
> Frank writes:
>> My ntp client changes clock (by small amount) at any time:
>> Jul 25 05:29:38 bax ntpd[10269]: adjusting local clock by 0.098724s
>> Jul 25 05:31:43 bax ntpd[10269]: adjusting local clock by 0.038991s
>> Jul 25 06:13:38 bax ntpd[10269]: adjusting local clock by -0.037131s
>> Jul 25 15:01:52 bax ntpd[10269]: adjusting local clock by -0.112429s
>
> Ken writes:
>> These do seem to be larger values than you might expect from a clock
>> conditioned with ntpd. Is it a VM or is there something going on that
>> would stop or suspend your system?
>
> There is certainly something wrong there.

System is not a VM; it runs 24/7 hosting for a few simple domains. It
runs OpenBSD, not Linux. I believe OpenBSD has it's own ntpd
implementation. I read once that the amount of time mentioned is how
much time clock needs to be changed, not how much the clock will
actually be changed. I know nothing about ntpd internals; thanks for
letting me hijack this thread. The log messages may be out-of-context,
since I excluded frequency changes. Still something wrong?

Jul 25 00:13:25 bax ntpd[10269]: adjusting local clock by -0.038453s
Jul 25 00:42:25 bax ntpd[10269]: adjusting clock frequency by -10.296223
to -20.774345ppm
Jul 25 02:38:31 bax ntpd[10269]: adjusting local clock by 0.039182s
Jul 25 04:56:29 bax ntpd[10269]: adjusting clock frequency by 3.332808
to -17.441537ppm
Jul 25 05:29:38 bax ntpd[10269]: adjusting local clock by 0.098724s
Jul 25 05:31:43 bax ntpd[10269]: adjusting local clock by 0.038991s
Jul 25 06:13:38 bax ntpd[10269]: adjusting local clock by -0.037131s
Jul 25 08:26:12 bax ntpd[10269]: adjusting clock frequency by -5.876526
to -23.318063ppm
Jul 25 11:07:08 bax ntpd[10269]: adjusting clock frequency by 16.235236
to -7.082827ppm
Jul 25 15:01:52 bax ntpd[10269]: adjusting local clock by -0.112429s
Jul 25 15:38:06 bax ntpd[10269]: adjusting clock frequency by -9.112840
to -16.195667ppm
Jul 25 20:42:03 bax ntpd[10269]: adjusting clock frequency by 1.838351
to -14.357316ppm
Jul 26 05:57:41 bax ntpd[10269]: adjusting clock frequency by -0.485347
to -14.842663ppm
Jul 26 15:48:01 bax ntpd[10269]: adjusting clock frequency by -0.130635
to -14.973298ppm
Jul 26 23:51:48 bax ntpd[10269]: adjusting clock frequency by -0.632588
to -15.605885ppm
Jul 27 09:14:44 bax ntpd[10269]: adjusting clock frequency by 0.761208
to -14.844677ppm
Jul 27 11:33:29 bax ntpd[5857]: adjusting local clock by 0.332560s
Jul 27 11:57:09 bax ntpd[5857]: adjusting clock frequency by -0.180636
to -15.025316ppm
Jul 27 12:16:16 bax ntpd[5857]: adjusting clock frequency by 0.153771 to
-14.871545ppm
Jul 27 12:38:36 bax ntpd[5857]: adjusting clock frequency by -0.314905
to -15.186450ppm
Jul 27 22:30:47 bax ntpd[5857]: adjusting clock frequency by -0.058928
to -15.245378ppm
Jul 28 22:00:57 bax ntpd[5857]: adjusting clock frequency by 0.508728 to
-14.750045ppm
Jul 29 07:09:05 bax ntpd[5857]: adjusting clock frequency by 0.056698 to
-14.693347ppm
Jul 29 21:25:01 bax ntpd[5857]: adjusting clock frequency by -0.233626
to -14.926974ppm
Jul 30 06:28:33 bax ntpd[5857]: adjusting clock frequency by -0.255362
to -15.182336ppm
Jul 30 15:45:17 bax ntpd[5857]: adjusting clock frequency by 0.291147 to
-14.891189ppm
Jul 31 11:57:51 bax ntpd[5857]: adjusting clock frequency by 0.198529 to
-14.725782ppm
Aug 1 08:47:12 bax ntpd[5857]: adjusting clock frequency by -0.063213
to -14.806622ppm
Aug 2 12:19:10 bax ntpd[5857]: adjusting clock frequency by 0.096080 to
-14.759072ppm
Aug 3 01:30:19 bax ntpd[5857]: adjusting clock frequency by -0.353416
to -15.112489ppm
Aug 3 08:10:34 bax ntpd[5857]: adjusting clock frequency by 0.251130 to
-14.861359ppm
Aug 3 20:29:11 bax ntpd[5857]: adjusting clock frequency by -0.105335
to -14.966694ppm
Aug 4 07:22:22 bax ntpd[27189]: adjusting local clock by -0.097095s
Aug 4 07:49:26 bax ntpd[27189]: adjusting clock frequency by -2.970136
to -17.898726ppm
Aug 4 08:04:04 bax ntpd[27189]: adjusting clock frequency by 2.495076
to -15.403651ppm