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From Dorian Hoxha <>
Subject Re: Way to write to dc1 but keep data only in dc2
Date Fri, 30 Sep 2016 19:49:24 GMT
Thanks Edward. Looks like it's not possible what I really wanted (to use
some kind of a quorum write ex).

Note that the queue is ordered, but I need just so they eventually happen,
but with more consistency than ANY (2 nodes or more).

On Fri, Sep 30, 2016 at 12:25 AM, Edward Capriolo <>

> You can do something like this, though your use of terminology like
> "queue" really do not apply.
> You can setup your keyspace with replication in only one data center.
> CREATE KEYSPACE NTSkeyspace WITH REPLICATION = { 'class' : 'NetworkTopologyStrategy',
'dc2' : 3 };
> This will make the NTSkeyspace like only in one data center. You can
> always write to any Cassandra node, since they will transparently proxy the
> writes to the proper place. You can configure your client to ONLY bind to
> specific hosts or data centers/hosts DC1.
> You can use a write consistency level like ANY. IF you use a consistency
> level like ONE. It will cause the the write to block anyway waiting for
> completion on the other datacenter.
> Since you mentioned the words "like a queue" I would suggest an
> alternative is to writing the data do a distributed commit log like kafka.
> At that point you can decouple the write systems either through producer
> consumer or through a tool like Kafka's mirror maker.
> On Thu, Sep 29, 2016 at 5:24 PM, Dorian Hoxha <>
> wrote:
>> I have dc1 and dc2.
>> I want to keep a keyspace only on dc2.
>> But I only have my app on dc1.
>> And I want to write to dc1 (lower latency) which will not keep data
>> locally but just push it to dc2.
>> While reading will only work for dc2.
>> Since my app is mostly write, my app ~will be faster while not having to
>> deploy to the app to dc2 or write directly to dc2 with higher latency.
>> dc1 would act like a queue or something and just push data + delete
>> locally.
>> Does this make sense ?
>> Thank You

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