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From Sylvain Lebresne <sylv...@datastax.com>
Subject Re: Setting up Cassandra to store on a specific node and not replicate
Date Wed, 18 Dec 2013 10:44:42 GMT
You seem to be well aware that you're not looking at using Cassandra for
what it is designed for (which obviously imply you'll need to expect
under-optimal behavior), so I'm not going to insist on it.

As to how you could achieve that, a relatively simple solution (that do not
require writing your own partitioner) would consist in using 2 datacenters
(that obviously don't have to be real physical datacenter), to put the one
that should have it all in one datacenter with RF=1 and to pull all other
nodes in the other datacenter with RF=0.

As Janne said, you could still have hint being written by other nodes if
the one storage node is dead, but you can use the system
property cassandra.maxHintTTL to 0 to disable hints.

--
Sylvain


On Wed, Dec 18, 2013 at 10:20 AM, Colin MacDonald
<colin.macdonald@sas.com>wrote:

>  Ahoy the list.  I am evaluating Cassandra in the context of using it as
> a storage back end for the Titan graph database.
>
>
>
> We’ll have several nodes in the cluster.  However, one of our
> requirements is that data has to be loaded into and stored on a specific
> node and only on that node.  Also, it cannot be replicated around the
> system, at least not stored persistently on disk – we will of course make
> copies in memory and on the wire as we access remote notes.  These
> requirements are non-negotiable.
>
>
>
> We understand that this is essentially the opposite of what Cassandra is
> designed for, and that we’re missing all the scalability and robustness,
> but is it technically possible?
>
>
>
> First, I would need to create a custom partitioner – is there any
> tutorial on that?  I see a few “you don’t need” to threads, but I do.
>
>
>
> Second, how easy is it to have Cassandra not replicate data between nodes
> in a cluster?  I’m not seeing an obvious configuration option for that,
> presumably because it obviates much of the point of using Cassandra, but
> again, we’re working within some rather unfortunate constraints.
>
>
>
> Any hints or suggestions would be most gratefully received.
>
>
>
> Kind regards,
>
>
>
> -Colin MacDonald-
>
>
>

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