When asynchronous replication is not best for your use-case, investigate how Postgres's [synchronous replication](http://www.postgresql.org/docs/current/static/warm-standby.html#SYNCHRONOUS-REPLICATION) works. Synchronous replication ensures consistency across a cluster by confirming that writes are written to a secondary before returning to the connecting client with a success. The cost of synchronous replication will be reduced throughput on writes. This throughput will be entirely based on network performance. In hosted datacenter environments (like AWS, Rackspace, or any network you do not control), synchrous replication increases the variability of write performance significantly. If followers become inaccessible from the leader, the leader will becomes effectively readonly.
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