My concern with Redis is reliability. Redis Cluster has problems with consistency [1], whereas unclustered Redis -- well, it syncs to disk every 10 seconds or so, but even then I'm concerned that the reliability of its on-disk structures haven't been as battle-tested as, say, PostgreSQL. Or has it?
Yeah, about that:
http://redis.io/topics/persistence
> Using AOF Redis is much more durable: you can have different fsync policies: no fsync at all, fsync every second, fsync at every query. With the default policy of fsync every second write performances are still great (fsync is performed using a background thread and the main thread will try hard to perform writes when no fsync is in progress.) but you can only lose one second worth of writes.
Redis is neet if your information fits in RAM, but that's not what Cassandra is for.
You can easily get commodity servers with 256GB of RAM per node x 10 shards. Cluster or not, as per your use case.
row key = key
column = field
I know Lua is "an option" in Redis but I avoid it like the plague because under production loads, Redis hashes perform and are easy to maintain w/o Lua.
