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https://issues.apache.org/jira/browse/CASSANDRA-3172?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13102162#comment-13102162
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Mark Guzman commented on CASSANDRA-3172:
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The assumption I'm making is that if this occurs then reads most likely will
occur from the same dc I've failed over to. Once I get back over to the
original dc, the further belief is that the background replication between DCs
will have at least propagated the write to some of the nodes. Enough to
hopefully provide a consistent view. That's the intent, the details of how I
get it to do that is up in the air. I may need to pin myself to the other DC
for a period of time, it depends on the details of replication setup like {A:3,
B:3, C:3}. My understanding is that the coordinator will contact a single node
in the other DCs to replicate the write and that this will succeed over time
even if the other DCs can not meet the same consistency requirements at the
time of the original write. Is this correct?
> Add CL.ANY_QUORUM to support quorum requests with cross datacenter failover
> ---------------------------------------------------------------------------
>
> Key: CASSANDRA-3172
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3172
> Project: Cassandra
> Issue Type: Improvement
> Components: API, Core
> Reporter: Mark Guzman
> Priority: Minor
>
> Currently we provide CL.LOCAL_QUORUM and CL.EACH_QUORUM. CL.ANY_QUORUM would
> operate like CL.LOCAL_QUORUM if a local quorum is possible, if it is not the
> coordinator would use its knowledge to select the "fastest/closest" node in
> another datacenter to attempt another LOCAL_QUORUM in. This would allow for
> simple reliable cross datacenter failover without putting the intelligence in
> the client. The client is intrinsically at a disadvantage since it doesn't
> have a current full picture of the rings.
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