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We have to build a multi-master replication system. That means the if we have N servers, the total number of connections between all those servers will be equals to : N x ( N - 1 ) / 2. If we have 4 servers, we will have 6 possibles connections. If we have 10 servers, we will have 45 possibles relationsetc. For 100 servers, this is 4500 possibles relations !!! Even if this is a polynomial growth, the reality s totally different. We won't allow such a scheme, which is totally out of control. In real world, having only two servers seems quite common, for small to large organization. If more servers are needed - for scalibility of to build a failover system, then we N to N communication network will not be implemented. We will generally select one or two "master" servers which will communicate with a few other servers, like in a chain.
Connection between servers
Between 2 servers
We have two cases : the servers are connected or they are disconnected :
or 
This is the simplest possible case, put aside a single server !
We will have to deal with two disconnected servers, and especially with retries when they get connected again.
The main considerations will be to replicate the data which are valid, as some of them may have been updated on both servers.
Inclusion into the Interceptors chain
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