I would like to set up databases that are put at different data centres around the world. For this, I think some nosql solutions may suit the case. For example, couchdb, maybe. Eventual consistency is ok for this.
The case does not limit to document based solution. But I would like to know the possibility, potential problems for setting up master-master replications around the world as I see the cases the servers are in same data centre most likely.
Thanks.