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From Emmanuel Lecharny <elecha...@iktek.com>
Subject Re: [replication] Master slave replication will not suffice
Date Thu, 24 Feb 2005 16:47:34 GMT
Le jeudi 24 février 2005 à 08:40 -0800, David Boreham a écrit :
> > Cool, this sounds interesting.  Let's say that server A gets an update 
> > to change foo=dog and and the same time server B gets an update to 
> > change foo=cat.  Replication takes a while and 15 minutes later, A gets 
> > the update to change foo=cat from B and B gets the update to change 
> > foo=dog.  How does that get resolved?
> 
> One of them wins. There are various possible choices,
> however you might find it useful to think of a 'principle
> of least surprise' here. e.g. if the change made later
> in time wins, that might be less of a surprise than if
> an earlier change wins.

You may also have a hierarchical strategy. A modification that occured
on a server A is less significant than the one made on the server B if
server B is a kind of "virtual master" of the server A.  

Both strategy (timestamped modification & hierarchical level) may be
used.



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