Re: [Exim] Multiple MySQL databases and hosts

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Author: V. T. Mueller
Date:  
To: Ollie Cook
CC: exim-users
Subject: Re: [Exim] Multiple MySQL databases and hosts
On Wed, 5 Dec 2001, Ollie Cook wrote:
>  mysql_servers = host1::3306/database1/user1/password1\
>                  host2::3306/database2/user2/password2
> If the "domains" table is on host2 and the "users" table is on host1
> when a mail arrives Exim will do three lookups:
>   1)  DOMAINS lookup on host1 which will fail because that table
>       doesn't exist on host1
>   2)  DOMAINS lookup on host2 which will succeed if the domain
>       is in the table on host2
>   3)  USERS lookup on host1 if #2 succeeds
> It seems wasteful to do query #1, here.


This mechanism provides redundancy, which indeed is something very
reasonable to do. If you experience performance issues, you can always
buy faster hardware. What if one of your machines fail? It will cause the
whole service to fail, because your design actually doubled the failure
rate instead of decreasing it.

The software's job is to offer smart and reliable means for
implementation, and this is exactly what exim does.

So I strongly oppose the change requested for v4 .

Regards,
Volker
--
V. T. Mueller      Freiburg, Germany     vtmue (at) uni-freiburg.de


           "problems are just opportunities in work cloth"