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https://issues.apache.org/jira/browse/CASSANDRA-7296?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15563258#comment-15563258
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Brian Hess commented on CASSANDRA-7296:
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Consistency Level does feel like the right approach. The THIS_ prefix is in
line with LOCAL_ in that it would identify the locus of nodes that are
available for consistency. With LOCAL_ONE, we need just one replica from the
data center of this coordinator. If no replicas exist (like the RF=0) then you
get UnavailableException. Namely, you don't reach out to other nodes and proxy
for another DC, etc. Also note that while the client can certainly see that
it's talking to a DC with no RF by looking at system tables or driver API
calls, we still throw the UnavailableException.
In the THIS_ONE, we are saying that the locus of available nodes for
consistency level is just the coordonator itself. If that node is not a
replica, then it should also throw an UnavailableException. It should not
silently go ask the actual replicas, just like in the LOCAL_ONE case we don't
ask other DCs. While it is true that the client could know that this node is
not a replica, it is the same as in LOCAL_ONE and RF.
> Add CL.COORDINATOR_ONLY
> -----------------------
>
> Key: CASSANDRA-7296
> URL: https://issues.apache.org/jira/browse/CASSANDRA-7296
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Tupshin Harper
>
> For reasons such as CASSANDRA-6340 and similar, it would be nice to have a
> read that never gets distributed, and only works if the coordinator you are
> talking to is an owner of the row.
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