I am evaluating cassandra to implement activity streams. We currently have over 1000000 feeds with total entries exceeding 320000000 implemented using redis ( ~320 entries / feed). Would like hear from the community on how to use cassandra to solve the following cases:
  1. Ability to fetch entries by applying a few filters ( like show me only likes from a given user). This would include range query to support pagination. So this would mean indices on a few columns like the feed id, feed type etc.
  2. We have around 3 machines with 4GB RAM for this purpose and thinking of having replication factor 2. Would 4GB * 3 be enough for cassandra for this kind of data? I read that cassandra does not keep all the data in memory but want to be sure that we have the right server config to handle this data using cassandra.