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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: distributing tokens equally along the key distribution space
Date Thu, 01 Oct 2009 16:48:41 GMT
On Thu, Oct 1, 2009 at 11:26 AM, Igor Katkov <ikatkov@gmail.com> wrote:
> Hi,
>
> Question#1:
> How to manually select tokens to force equal spacing of tokens around the
> hash space?

(Answered by Jun.)

> Question#2:
> Let's assume that #1 was resolved somehow and key distribution is more or
> less even.
> A new node "C" joins the cluster. It's token falls somewhere between two
> other tokens on the ring (from nodes "A" and "B" clockwise-ordered). From
> now on "C" is responsible for a portion of data that used to exclusively
> belong to "B".
> a. Cassandra v.0.4 will not automatically transfer this data to "C" will it?

It will, if you start C with the -b ("bootstrap") flag.

> b. Do all reads to these keys fail?

No.

> c. What happens with the data reference by these keys on "B"? It will never
> be accessed there, therefor it becomes garbage. Since there are to GC will
> it stick forever?

nodeprobe cleanup after the bootstrap completes will instruct B to
throw out data that has been copied to C.

> d. What happens to replicas of these keys?

These are also handled by -b.

-Jonathan

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