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From Sam Overton <...@acunu.com>
Subject Re: RFC: Cassandra Virtual Nodes
Date Tue, 20 Mar 2012 11:40:13 GMT
On 20 March 2012 04:35, Vijay <vijay2win@gmail.com> wrote:
> On Mon, Mar 19, 2012 at 8:24 PM, Eric Evans <eevans@acunu.com> wrote:
>
>> I'm guessing you're referring to Rick's proposal about ranges per node?
>>
>
> May be, what i mean is little more simple than that... We can consider
> every node having a multiple conservative ranges and moving those ranges
> for bootstrap etc, instead of finding the mid point etc in the bootstrap
> code. Once we get that working all the way to the FS/Streaming then we can
> move those ranges and assign those ranges to nodes in random orders. Hope
> it makes sense.

I agree that this should be approached in incremental steps. Rick
already raised concerns about stability issues which might arise from
changing large parts of code at once.

I would anticipate the first step to be, exactly as you suggest, to
support multiple tokens per host instead of just one. Presumably in
your suggestion you imagine these tokens to define contiguous ranges
for a given host, so that the distribution model is the same as
before, but bootstrap can be done incrementally.

This would be a great first step. The extension to a virtual node
scheme as described previously is then fairly trivial. The only
additional change needed is to assign the tokens in some other way
which does not restrict the ranges to being contiguous.

-- 
Sam Overton
Acunu | http://www.acunu.com | @acunu

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