I am looking for an eventually consistent data store and it looks like it may be coming down to Riak or Cassandra. Has anyone got expereinces of a view on this?
Answer
As you probably know, they are both architecturally strongly influenced by Dynamo (eventually consistent, no single points of failure, etc). Both also go beyond Dynamo in providing a "richer than pure K/V" data model -- in Cassandra's case, providing a Bigtable-like ColumnFamily mode, in Riak's, a Document-oriented one. I have seen sane people choose both.
I believe points that favor Cassandra include
- speed
- support for clusters spanning multiple data centers
- big names using it (digg, twitter, facebook, webex, ... -- http://n2.nabble.com/Cassandra-users-survey-tp4040068p4040393.html)
Points that favor Riak include
- map/reduce support out of the box
/Cassandra dev, fwiw