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From AJ>
Subject Re: Docs: Token Selection
Date Fri, 17 Jun 2011 19:55:55 GMT
On 6/17/2011 1:27 PM, Sasha Dolgy wrote:
> Replication factor is defined per keyspace if i'm not mistaken.  Can't
> remember if NTS is per keyspace or per cluster ... if it's per
> keyspace, that would be a way around it ... without having to maintain
> multiple clusters .... just have multiple keyspaces ...

Hey!  I think you're on to something Sasha!  Placement strat and RF are 
both defined per ks.  I'll let that stew for a while in my brain.


> On Fri, Jun 17, 2011 at 9:23 PM, AJ<>  wrote:
>> On 6/17/2011 12:32 PM, Jeremiah Jordan wrote:
>>>         Run two clusters, one which has {DC1:2, DC2:1} and one which is
>>> {DC1:1,DC2:2}.  You can't have both in the same cluster, otherwise it
>>> isn't possible to tell where the data got written when you want to read
>>> it.  For a given key "XYZ" you must be able to compute which nodes it is
>>> stored on just using "XYZ", so a strategy where it is on nodes
>>> DC1_1,DC1_2, and DC2_1 when a node in DC1 is the coordinator, and to
>>> DC1_1, DC2_1 and DC2_2 when a node in DC2 is the coordinator won't work.
>>> Given just "XYZ" I don't know where to look for the data.
>>>         But, from the way you describe what you want to happen, clients
>>> from DC1 aren't using data inserted by clients from DC2, so you should
>>> just make two different Cassandra clusters.  Once for the DC1 guys which
>>> is {DC1:2, DC2:1} and one for the DC2 guys which is {DC1:1,DC2:2}.
>> Interesting.  Thx.

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