On Fri, Oct 25, 2013 at 2:47 PM, srmore <comom...@gmail.com> wrote: > I don't know whether this is possible but was just curious, can you query > for the data in the remote datacenter with a CL.ONE ? >
A coordinator at CL.ONE picks which replica(s) to query based in large part on the dynamic snitch. If your remote data center has a lower badness score from the perspective of the dynamic snitch, a CL.ONE request might go there. 1.2.11 adds [1] a LOCAL_ONE consistencylevel which does the opposite of what you are asking, restricting CL.ONE from going cross-DC. > There could be a case where one might not have a QUORUM and would like to > read the most recent data which includes the data from the other > datacenter. AFAIK to reliably read the data from other datacenter we only > have CL.EACH_QUORUM. > Using CL.QUORUM requires a QUORUM number of responses, it does not care from which data center those responses come. > Also, is there a way one can control how frequently the data is replicated > across the datacenters ? > Data centers don't really exist in this context [2], so your question is "can one control how frequently data is replicated between replicas" and the answer is "no." All replication always goes to every replica. =Rob [1] https://issues.apache.org/jira/browse/CASSANDRA-6202 [2] this is slightly glib/reductive/inaccurate, but accurate enough for the purposes of this response.
