Re: [Sqlgrey-users] SQL Query optimization

[Klaus A. S. <kse...@gm...>]

Michel Bouissou <mi...@bo...> wrote:

>> I was thinking that backup MXes might use the same database as
>> the primary MX, and they might be in different timezones.
>=20
> They would probably not use the database directly, but maybe indirectly
> thru using the same SQLgrey server. The timestamps are then the
> "internals" of the SQLgrey server, and are not known to the MXes.

I was actually imagining several sqlgrey daemons connecting to the
same central database, but of course the scenario you mention is also
possible.

>> What happens to localtime() timestamps (and intervals) as we pass from
>> standard time to daylight saving time?
>=20
> Not much. Addresses in AWLs may be kept one hour more or less than
> planned (let's say 1 month +/- 1 hour instead of 1 month), which doesn't
> really matter, does it ?
>=20
> Addresses in connect will be kept waiting for a reconnection for 1 more/l=
ess
> hour, which shouldn't have a big incidence either.

It doesn't matter much, but the difference is there.
=20
> What may be more noticeable is that, at the time the DST changes (in the
> middle of the night) the "minimum time before accepting reconnection" may
> become one hour longer, or not enforced at all, for one hour.

It will be in the middle of the night at the database machine, but
mail might be fetched with e.g. IMAP/POP from everywhere on the globe,
or forwarded from the MX to other mail accounts in other timezones.
=20
> The practical consequences for this will be IMHO insignificant.

Whether it will be insignificant will depend on the actual sitation
and use of that particular MX.  IMHO the only sane thing to do when
dealing with timestamps for other than human consumption is to use
UTC.

Cheers,

--=20
Klaus Alexander Seistrup
SubZeroNet =B7 Copenhagen =B7 Denmark