It doesn't yet. It's on our nebulous "we'd like to do this some time" roadmap, but currently concentrating on some more basic stuff around stability and time series features.
Of course this is a huge optimization for data warehousing applications, where two co-partitioned tables can be joined without any network data transfer, and in some cases could even use merge join instead of hash based strategies. But, it's the usual time/scope/quality trinity, and we'd rather not compromise the third element.
Glad to hear this is at least being considered. The optimizations for data warehousing you mentioned are my use case. I understand the it is a very active project with a lot on the road map. It's a very cool project and I follow you guys on http://gerrit.cloudera.org/#/q/status:open
Of course this is a huge optimization for data warehousing applications, where two co-partitioned tables can be joined without any network data transfer, and in some cases could even use merge join instead of hash based strategies. But, it's the usual time/scope/quality trinity, and we'd rather not compromise the third element.