When we were eager to find a better data base for raspberry pi, rethinkdb drew our attention. It is extremely easy to set up, even for multi-nodes. In addition, it also has built-in web front end interface, which means we can spend less time developing user interface for the database.
However, even though the developers at rethindb just claimed arm support, the database itself on raspberry pi is not stable. In other words, rethinkdb on raspberry pi is still experimental, as the developers said in the build bash.
Despite the fact that raspberry pi cluster cannot functions normally, we still managed to get some benchmark. The reading spead is around 18 record/second and the writing speed is 600 record/second. Thus, based on its performance on raspberry pi, we are not able to use rethinkdb as desirable database as it cannot handle massive input.