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Posted to user@cassandra.apache.org by Yang <te...@gmail.com> on 2012/11/01 08:09:28 UTC

LOCAL_QUORUM vs EACH_QUORUM

the following comment in the code describes them very clearly:

*   LOCAL_QUORUM Returns the record with the most recent timestamp once a
majority of replicas within the local datacenter have replied.
 *   EACH_QUORUM  Returns the record with the most recent timestamp once a
majority of replicas within each datacenter have replied.


but it seems that my intended use case is not solved by either policy:
I have 2 colos,  mostly I want to run my application in the primary-backup
(or "hot/warm" ) mode, though everything is automated, and a human "switch
over" is not needed in case of one colo failure. I want all writes/reads to
get a quorum from local colo,  then at least make sure that 1 write has
propagated to the other colo.

So I do not necessarily need a Quorum from remote colos, but I need at
least one write to arrive there.

does that sound like a common use case? within the current code, is there a
way to achieve that? if not, creating a new policy does not seem too
difficult either.

Thanks
Yang