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Comment by jwr | Hacker News Reader

Redis is unbelievably cool. It is so easy to set it up and connect to it in Clojure that I find myself using it whenever I need to cache anything with persistence between runs. Even for a single set of data it's actually easier to use Redis than deal with data files and their problems (naming, overwriting, concurrent access, etc).

Redis is also great because it's essentially a collection of data structures with concurrent programming primitives, persistence added on top. Data structures mean you can offload quite a bit of work onto it. For example, we use it to cache search results — and you can do results paging entirely from within redis (LRANGE).

It isn't really comparable to Cassandra, they really do different things. Also, I am not a fan of the whole "NoSQL" thing. I use PostgreSQL when it makes sense, and Redis when Redis makes sense.

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We just rewrote our app from a Postgres backend to a Redis backend. The main difference I see with using NoSQL vs traditional SQL is that you massage the data during insert time so when you goto to look it up later it's pretty much already in the form you need it. This makes lookups super fast, regardless of whether you're paging or not.

I can honestly say I'll never look back. Traditional SQL had a nice run but the incredible gains in simplicity and performance with nosql are indisputable - especially performance.

Case in point: In our initial testing it looks like the Redis setup will be able to support approx 10,000 accounts on one modest dedicated server vs about 100-200 accounts using Postgres.

I think Redis is great (i'm using it for a few apps as a backend store for resque, and soon as a rails partial cache with better control over expiration based on an object's dependency-graph).

Yet, I don't understand why people use such superlatives constantly about it. Is anyone else a happy user but a bit overwhelmed by the hype? (And i hesitate to use that word because it sounds overly negative.) Call me a student of human psychology noticing a trend that in this case happens to be in my interests. It would be much more irritating if I hated Redis - I don't, but I still can't ignore the squirmy feeling i get when I read about it...

if you want my opinion, people are tired of seeing stuff that are hard to work with. I think Redis has its value, but part of the hype is clearly the fact that it is something simple, clear, non ad-hoc (we only care about CS data structures). A pretty alien concept in the database world.

Valid point. Perhaps i'm mistaking the overflow of emotion for 'relief' - in that it was a missing tool in the developer toolbelt.

One thing I really like about Redis is that it is not concurrent at all. It runs in a single thread - it's just really freaking fast

Verging on the off-topic: how are you dealing with mixing persistence and Clojure's STM?

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