Preprocessing option has been added to the Operation interface to allow changing the operation's consistency level before execution.

Current implementation allows to change consistency level dynamically. This mechanism can be extended to support different options.
If you use replication factor 2, and consistency level LOCAL_QUORUM, write requests will fail if one of the replica servers is down. if you use replication factor 3 this situation is not critical. To solve the problem we change the consistency level dynamically.