[Opensource] db-replication

[larry hamel]

My first reaction was to suggest a DBObject subclass that employs a number N of DB connections for writing, but which only tries tries 1 connection for reading (retrying different connections upon failure for reading).

however, there's a catch:  suppose you got all this working, and then one DB goes down.  the application gracefully keeps going, but only N-1 DBs are getting updates now, and to bring the Nth DB back online, you have to synchronize.  you'd have to keep a transaction log of everything, and somehow have a roll-forward on the Nth DB.  that is starting to sound like rewriting all the replication code already written within enterprise DBs.  maybe you need to do such work, but I suspect it would be a lot easier to figure out how to make the built-in DB replication work despite your tough requirements.

larry

At 12:53 AM 12/11/2002, you wrote:
>Hi there, 
>Does someone know if there is any possibility to make (n>=2 - way) 
>replications between databases on n >= 2 machines? 
>We want to improve the reliability of our webservice termidat.de 
>using two absolutely identical machines with diffent url's, so 
>that the user can visit yyy.de if xxx.de is broken down vice versa. 
>in normal operatig state (both are up) it shoudn't matter, which 
>machine is used. 
>For us it is not possible to use the low-level replication deliverd with the 
>DB, because a) some special cases must be treated by hand. (contratictory 
>data entered in the time-window before replication has finished) and 
>b) communication must be secure (encrypted). c) we don't want to be bound 
>to the limit of 2 machines. 
>autoincrements and atomicity of transations are no problem. 
>Thanks a lot 
>Johann 
>
>
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