Learning Apache Cassandra - Second Edition

Local consistency levels

With multidata centers, requests can go to any data center. Often, when using the QUORUM consistency, requests go to both data centers before returning a successful result. This introduces cross-data center latency and is detrimental in situations where latency has to be minimal. To avoid this, Cassandra provides the LOCAL consistency levels. The alternatives for the ONE and QUORUM consistency levels in a multidata center scenario are the LOCAL_ONE and LOCAL_QUORUM consistency levels.

In the case of the LOCAL_ONE consistency, the request is successful as soon as one of the replica writes/reads on the local data center returns acknowledgement. By local data center, we mean the data center where the coordinator node ...