Christopher Browne wrote:
> Andreas Pflug <pgadmin at pse-consulting.de> writes:
> 
>>Having all machine's clocks in time sync is a requirement of slony
>>that seems quite obvious. Still, if this requirement is not met for
>>whatever reason (maybe an admin is 110 % sure ntpd is running, but it
>>stalled), things might get screwed up in a way that's not easy to
>>debug.
>>After a brief look at slon, it seems that local time is used for
>>checking timeouts only (the only insert into a timestamp column uses
>>now()), so problems from clock drift are unlikely to appear from
>>that. But databases servers still might deviate, how about a check in
>>slon that checks regularly if the servers in use are sufficiently in
>>sync? Maybe slon should even refuse to run/stop working if server
>>clocks (checked with now(), not timeofday()) are not sufficiently
>>in-sync.
> 
> 
> It seems an excellent idea to run some utility completely outside slon
> that checks for clock deviations and warns someone.
> 
> I could see it being an interesting possiblity for that to lead to
> knocking down the slons, but that seems like a local policy that
> Slony-I doesn't need to impose itself.

Hm, slon knows best what amount of deviation is tolerable (there's the 
10 minutes limit when cleaning events, so is this the tolerance?).
Why shouldn't slon check itself for his operating environment?

Regards,
Andreas