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From Vijay <vijay2...@gmail.com>
Subject Re: Docs: Token Selection
Date Wed, 15 Jun 2011 23:51:28 GMT
No it wont.... it will assume you are doing the right thing...

Regards,
</VJ>



On Wed, Jun 15, 2011 at 2:34 PM, AJ <aj@dude.podzone.net> wrote:

>  Vijay, thank you for your thoughtful reply.  Will Cass complain if I don't
> setup my tokens like in the examples?
>
>
> On 6/15/2011 2:41 PM, Vijay wrote:
>
> All you heard is right...
> You are not overriding Cassandra's token assignment by saying here is your
> token...
>
>  Logic is:
> Calculate a token for the given key...
> find the node in each region independently (If you use NTS and if you set
> the strategy options which says you want to replicate to the other
> region)...
> Search for the ranges in each region independntly
> Replicate the data to that node.
>
> For multi DC cassandra needs nodes to be equally partitioned within each
> dc (If you care that the load equally distributed).... as well as
> there shouldn't be any collusion of tokens within a cluster....
>
>  The documentation tried to explain the same and the example in the
> documentation.
> Hope this clarifies...
>
>  More examples if it helps....
>
>   DC1 Node 1 : token 0
> DC1 Node 2 : token 8..
>
>  DC2 Node 1 : token 4..
> DC2 Node 1 : token 12..
>
>  or
>
>  DC1 Node 1 : token 0
> DC1 Node 2 : token 1..
>
>  DC2 Node 1 : token 8..
> DC2 Node 1 : token  7..
>
>  Regards,
> </VJ>
>
>
>
> On Wed, Jun 15, 2011 at 12:28 PM, AJ <aj@dude.podzone.net> wrote:
>
>>  On 6/15/2011 12:14 PM, Vijay wrote:
>>
>> Correction....
>>
>>  "The problem in the above approach is you have 2 nodes between 12 to 4
>> in DC1 but from 4 to 12  you just have 1"
>>
>>  should be
>>
>>  "The problem in the above approach is you have 1 node between 0-4 (25%)
>> and and one node covering the rest which is 4-16, 0-0 (75%)"
>>
>> Regards,
>> </VJ>
>>
>>
>>  Ok, I think you are saying that the computed token range intervals are
>> incorrect and that they would be:
>>
>> DC1
>> *node 1 = 0      Range: (4, 16], (0, 0]
>>
>> node 2 = 4      Range: (0, 4]
>>
>> DC2
>>  *node 3 = 8      Range: (12, 16], (0, 8]
>>
>> node 4 = 12   Range: (8, 12]
>>
>>  If so, then yes, this is what I am seeking to confirm since I haven't
>> found any documentation stating this directly and that reference that I gave
>> only implies this; that is, that the token ranges are calculated per data
>> center rather than per cluster.  I just need someone to confirm that 100%
>> because it doesn't sound right to me based on everything else I've read.
>>
>> SO, the question is:  Does Cass calculate the consecutive node token
>> ranges A.) per cluster, or B.) for the whole data center?
>>
>> From all I understand, the answer is B.  But, that documentation
>> (reprinted below) implies A... or something that doesn't make sense to me
>> because of the token placement in the example:
>>
>> "With NetworkTopologyStrategy, you should calculate the tokens the nodes
>> in each DC independantly...
>>
>> DC1
>> node 1 = 0
>> node 2 = 85070591730234615865843651857942052864
>>
>> DC2
>> node 3 = 1
>> node 4 = 850705917302346158658436518579
>> 42052865"
>>
>>
>> However, I do see why this would be helpful, but first I'm just asking if this token
assignment is absolutely mandatory
>> or if it's just a technique to achieve some end.
>>
>>
>>
>>
>
>

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