Is eventual Consistency possible in case of Master - Master Configuration -

Question

Is eventual Consistency possible in case of Master - Master Configuration. ie if their are more than one master to accept writes then we can always have conflicting writes in case of eventual consistency.

for example : two master writing two user profile with same email id. In case of an eventual consistent system both masters may be able to successfully commit two user-profile with same email id - which is actual an inconsistent system

Answer 1

One: Locks are taken up before writing to the database or a cache.

Two: If the locks are taken up at the same time then there are further two more ways to resolve.

• Either an election is made among the two operations and one is elected whereas the other operation is rejected to the client and with it is returned the new value.
• Or distributed servers allow you to write a conflict resolution code and be deployed at the server, and is executed when this happens.

Usually topologies don't work that way, they distribute writes and there is a master and slave concept in a master master configurations as well. :)

Speaking theoretical of course.