It seems like you could use a composite key partioner to accomplish this
On Monday, November 7, 2011, Daniel Doubleday <firstname.lastname@example.org> wrote:
> Allow for deterministic / manual sharding of rows.
> Right now it seems that there is no way to force rows with different row keys will be stored on the same nodes in the ring.
> This is our number one reason why we get data inconsistencies when nodes fail.
> Sometimes a logical transaction requires writing rows with different row keys. If we could use something like this:
> prefix.uniquekey and let the partitioner use only the prefix the probability that only part of the transaction would be written could be reduced considerably.
> On Nov 1, 2011, at 11:59 PM, Jonathan Ellis wrote:
>> Hi all,
>> Two years ago I asked for Cassandra use cases and feature requests.
>>  The results  have been extremely useful in setting and
>> prioritizing goals for Cassandra development. But with the release of
>> 1.0 we've accomplished basically everything from our original wish
>> list. 
>> I'd love to hear from modern Cassandra users again, especially if
>> you're usually a quiet lurker. What does Cassandra do well? What are
>> your pain points? What's your feature wish list?
>> As before, if you're in stealth mode or don't want to say anything in
>> public, feel free to reply to me privately and I will keep it off the
>>  http://email@example.com/msg01148.html
>>  http://firstname.lastname@example.org/msg01446.html
>>  http://email@example.com/msg01524.html
>> Jonathan Ellis
>> Project Chair, Apache Cassandra
>> co-founder of DataStax, the source for professional Cassandra support