How to make Riak data localized?

I'm designing a Riak cluster at the moment and wondering if it is possible to hint Riak that a specific bunch of keys should be placed on a single node of the cluster?

For example, there is some private data for the user, that only she is able to access. This data contains ~10k documents (too large to be kept in one key/document), and to serve one page, we need to retrieve ~100 of them. It would be better to keep the whole bunch on a single node + have the applic开发者_如何学Goation on the same instance to make this faster.

AFAIK it is easy on Cassandra: just use OrderedPartitioner and keys like this: <hash(username)>/<private data key>. That way, almost all user keys will be kept on a single node.

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One of the points of using Riak is that your data is replicated and evenly distributed throughout the cluster, thus improving your tolerance for network partitions and outages. Placing data on specific nodes goes against that goal and increases your vulnerability.