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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: Replicate changes from DC1 to DC2, but not from DC2 to DC1
Date Tue, 22 Feb 2011 18:49:09 GMT
That would cause a lot of subtle breakage, e.g. confusing Repair.

2011/2/22 Héctor Izquierdo Seliva <izquierdo@strands.com>:
> El mar, 22-02-2011 a las 08:46 +1300, Aaron Morton escribió:
>> Take a look at the NetworkTopologyStrategy and/or the RackInferringSnitch together
they  decide where to place replicas. It's probably not a great idea to muck around with
this stuff though.
>>
>> How about a hadoop job to pull out the data you want? It would be a full scan but
in parallel.
>
> I looked at that, but correct me If i'm wrong, schema changes are
> distributed to all nodes, and they all have to agree on a version, so I
> can't have a keyspace A in DC1 with NetworkTopologyStrategy with options
> = [{DC1:1,DC2:1}] and the same keyspace in DC2 with options [{DC2:1,
> DC1:0}]. Is that correct?
>
>> Aaron
>>
>> On 22/02/2011, at 3:10 AM, Héctor Izquierdo Seliva <izquierdo@strands.com>
wrote:
>>
>> >
>> > Hi all.
>> >
>> > Is there a way (besides changing the code) to replicate data from a Data
>> > center 1 to a Data center 2, but not the other way around? I need to
>> > have a preproduction environment with production data, and ideally with
>> > only a fraction of the data (for example, by key preffixes). I have
>> > poked around StorageProxy and I can make writes in DC2 not replicate to
>> > DC1, and as long as I use DC_QUORUM it stays that way, but it
>> > looks...dangerous. I could do a full key scan but it would take too
>> > long.
>> >
>> > Have anybody done something similar?
>> >
>> > Thanks!
>> >
>> >
>
>
>



-- 
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of DataStax, the source for professional Cassandra support
http://www.datastax.com

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