Joins and transactions across nodes, very cool. Inner joins/right joins too? Do these have similar time complexity, latency/bandwidth aside, as a comparably indexed traditional RDBMS?
Tuning to perform these efficiently in a distributed manner is a work in progress (this is wrt the time complexity question). The hints used by a traditional RDBMS would not be effective in the distributed case - optimizing this requires changing the optimizer and doing more "push-downs" to optimize the queries. Currently, depending on the query, these may or may not be fully optimized - but we hope to have good coverage soon!