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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: Off line client nodes?
Date Mon, 12 Apr 2010 20:53:56 GMT
Cassandra treats disconnection as something that *does* occur, like it
or not, and deals with it well.

But there's no way to easily sync just some subset of data to your
laptop.  Couch may well be better at doing that sort of thing.

On Mon, Apr 12, 2010 at 3:50 PM, David Timothy Strauss
<david@fourkitchens.com> wrote:
> It's not common for me to recommend CouchDB, but this is one instance it's great for:
synching complete datasets for disconnected use. Cassandra treats disconnection as a problem,
not something that should occur in the normal plan of operations.
>
> -----Original Message-----
> From: Colin Yates <colin.yates@gmail.com>
> Date: Mon, 12 Apr 2010 10:52:32
> To: <user@cassandra.apache.org>
> Subject: Off line client nodes?
>
> Hi,
>
> In our architecture, our consultants want to perform some
> analysis on the train, disconnected from the web.
>
> How can I achieve this in Cassandra?  I realise this isn't quite
> the use-case that was thought about when the clustering
> was designed, but will it work?
>
> Scenario:
>
>  - consultantA is in his office running a cassandra
> node on his laptop.
>
>  - this node *very* periodically (almost on a manual basis)
> connects to the cluster and synchronises
>
>  - consultant then gets some coffee
>
>  - consultant then disconnects and sits on a train, happily
> using their app against the local node
>
>  - consultant goes and plays golf whilst billing client for
> 'management activities) (we know you do!)
>
>  - consultant plugs in at the end of the day and all changes are
> synced back to the cluster
>
> A few caveats:
>
>  - the sync might not be atomic - the consultant *will* get bored
> and disconnect before the sync has finished
>
>  - the consultant should only see a tiny, well-defined fragment
> of the cluster data - i.e. a key range-set for example
>
> Is this do-able or should I write a custom 'slurper' which
> builds the local standalone client node?  I really don't want to do this....
>
> Many thanks,
>
> Col
>
>

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