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From Manu Zhang <owenzhang1...@gmail.com>
Subject Re: Understanding Virtual Nodes on Cassandra 1.2
Date Thu, 31 Jan 2013 10:47:58 GMT
On Thu 31 Jan 2013 03:43:32 AM CST, Zhong Li wrote:
> Are there tickets/documents explain how data be replicated on Virtual
> Nodes? If there are multiple tokens on one physical host, may a chance
> two or more tokens chosen by replication strategy located on same
> host? If move/remove/add a token
> manually, does Cassandra Engine validate the case?
>
> Thanks.
>
>
> On Jan 30, 2013, at 12:46 PM, Zhong Li wrote:
>
>>> You add a physical node and that in turn adds num_token tokens to
>>> the ring.
>>
>> No, I am talking about Virtual Nodes with order preserving
>> partitioner. For an existing host with multiple tokens setting list
>> on cassandra.inital_token. After initial bootstrapping, the host will
>> not aware changes of cassandra.inital_token. If I want add a new
>> token( virtual node), I have to rebuild the host with new token list.
>>
>> My question is if there is way to add a virtual nodes without rebuild it?
>>
>> Thanks,
>>
>> On Jan 30, 2013, at 10:21 AM, Manu Zhang wrote:
>>
>>> On Wed 30 Jan 2013 02:29:27 AM CST, Zhong Li wrote:
>>>> One more question, can I add a virtual node manually without reboot
>>>> and rebuild a host data?
>>>>
>>>> I checked nodetool command, there is no option to add a node.
>>>>
>>>> Thanks.
>>>>
>>>> Zhong
>>>>
>>>>
>>>> On Jan 29, 2013, at 11:09 AM, Zhong Li wrote:
>>>>
>>>>> I was misunderstood this
>>>>> http://www.datastax.com/dev/blog/virtual-nodes-in-cassandra-1-2 ,
>>>>> especially
>>>>> "If you want to get started with vnodes on a fresh cluster, however,
>>>>> that is fairly straightforward. Just don’t set the
>>>>> |initial_token| parameter in your|conf/cassandra.yaml| and instead
>>>>> enable the |num_tokens| parameter. A good default value for this
>>>>> is 256"
>>>>>
>>>>> Also I couldn't find document about set multiple tokens
>>>>> for cassandra.inital_token
>>>>>
>>>>> Anyway, I just tested, it does work to set  comma separated list of
>>>>> tokens.
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Zhong
>>>>>
>>>>>
>>>>> On Jan 29, 2013, at 3:06 AM, aaron morton wrote:
>>>>>
>>>>>>> After I searched some document on Datastax website and some old
>>>>>>> ticket, seems that it works for random partitioner only, and
leaves
>>>>>>> order preserved partitioner out of the luck.
>>>>>> Links ?
>>>>>>
>>>>>>>  or allow add Virtual Nodes manually?
>>>>>> If not looked into it but there is a cassandra.inital_token startup
>>>>>> param that takes a comma separated list of tokens for the node.
>>>>>>
>>>>>> There also appears to be support for the ordered partitions to
>>>>>> generate random tokens.
>>>>>>
>>>>>> But you would still have the problem of having to balance your row
>>>>>> keys around the token space.
>>>>>>
>>>>>> Cheers
>>>>>> -----------------
>>>>>> Aaron Morton
>>>>>> Freelance Cassandra Developer
>>>>>> New Zealand
>>>>>>
>>>>>> @aaronmorton
>>>>>> http://www.thelastpickle.com <http://www.thelastpickle.com/>
>>>>>> <http://www.thelastpickle.com/>
>>>>>>
>>>>>> On 29/01/2013, at 10:31 AM, Zhong Li <zli@voxeo.com
>>>>>> <mailto:zli@voxeo.com>
>>>>>> <mailto:zli@voxeo.com>> wrote:
>>>>>>
>>>>>>> Hi All,
>>>>>>>
>>>>>>> Virtual Nodes is great feature. After I searched some document
on
>>>>>>> Datastax website and some old ticket, seems that it works for
>>>>>>> random partitioner only, and leaves order preserved partitioner
out
>>>>>>> of the luck. I may misunderstand, please correct me. if it doesn't
>>>>>>> love order preserved partitioner, would be possible to add support
>>>>>>> multiple initial_token(s) for  order preserved partitioner  or
>>>>>>> allow add Virtual Nodes manually?
>>>>>>>
>>>>>>> Thanks,
>>>>>>>
>>>>>>> Zhong
>>>>>>
>>>>>
>>>>
>>>
>>> You add a physical node and that in turn adds num_token tokens to
>>> the ring.
>>
>

no, those tokens will be skipped

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