happy to explore other choices together with the community.
Some users have voted Riak: https://predictionio.uservoice.com/forums/219398-general/sug...
56 karma · joined January 17, 2012
There is no specific reason reason to stick with MongoDB only. It just happens to be the database the team has picked for the first implementation. It is very likely to support other databases in the coming future given the strong community demand.