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The "API" page has been changed by TylerHobbs. The comment on this change is: ConsistencyLevel ZERO doesn't exist in 0.7. http://wiki.apache.org/cassandra/API?action=diff&rev1=22&rev2=23 -------------------------------------------------- ==== Write ==== ||'''Level''' ||'''Behavior''' || - ||`ZERO` ||Ensure nothing. A write happens asynchronously in background. Until [[https://issues.apache.org/jira/browse/CASSANDRA-685|CASSANDRA-685]] is fixed: If too many of these queue up, buffers will explode and bad things will happen. || ||`ANY` ||Ensure that the write has been written to at least 1 node, including HintedHandoff recipients. || ||`ONE` ||Ensure that the write has been written to at least 1 replica's commit log and memory table before responding to the client. || ||`QUORUM` ||Ensure that the write has been written to `N / 2 + 1` replicas before responding to the client. || @@ -44, +43 @@ ==== Read ==== ||'''Level''' ||'''Behavior''' || - ||`ZERO` ||Not supported, because it doesn't make sense. || ||`ANY` ||Not supported. You probably want ONE instead. || ||`ONE` ||Will return the record returned by the first replica to respond. A consistency check is always done in a background thread to fix any consistency issues when `ConsistencyLevel.ONE` is used. This means subsequent calls will have correct data even if the initial read gets an older value. (This is called ReadRepair) || ||`QUORUM` ||Will query all replicas and return the record with the most recent timestamp once it has at least a majority of replicas (`N / 2 + 1`) reported. Again, the remaining replicas will be checked in the background. ||
