I'm using memcached for some caching in my Rails 3 app through the simple Rails.cache interface and now I'd like to do some background job processing with redis and resque.
I think they're different enough to warrant using both. On heroku though, there are separate fees to use both memcached and redis. Does it make sense to use both or should I migrate to just using redis?
I like using memcached for caching because least recently used keys automatically get pushed out of the cache and I don't need the cache data to persist. Redis is mostly new to me, but I understand that it's persistent by default and that keys do not expire out of the cache automatically.
EDIT: Just wanted to be more clear with my question. I know it's feasible to use only Redis instead of both. I guess I just want to know if there are any specific disadvantages in doing so? Considering both implementation and infrastructure, are there any reasons why I shouldn't just use Redis? (I.e., is memcached faster for simple caching?) I haven't found anything definitive either way.