I do think space could be an issue. To mitigate against this risk I've decided to only keep ~8 pages of each feed in Redis, and compress the values (including removing attributes that won't be shown in the feed). Also, Redis 2.2 is a lot more space efficient than earlier versions.
Our primary datastore is actually MongoDB, which has some similar (NoSQL) characteristics, but I've found that storing the feeds in Redis is actually cheaper than storing the same data in Mongo. That said, I really like Mongo for its richer querying (and greater persistence guarantees), and use it for canonical storage of users, posts, etc.
I do think space could be an issue. To mitigate against this risk I've decided to only keep ~8 pages of each feed in Redis, and compress the values (including removing attributes that won't be shown in the feed). Also, Redis 2.2 is a lot more space efficient than earlier versions.
Our primary datastore is actually MongoDB, which has some similar (NoSQL) characteristics, but I've found that storing the feeds in Redis is actually cheaper than storing the same data in Mongo. That said, I really like Mongo for its richer querying (and greater persistence guarantees), and use it for canonical storage of users, posts, etc.