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Comment by endymi0n | Hacker News Reader

Cassandra is ugly, hardcore and performant as hell. It's not meant for the casual user, it's really meant to be there for you at scales where MongoDB craps its pants. If you wrap your head around ColumnFamilies, tunable consistency and NetworkTopologySnitch strategies, you get rewarded by a database that can scale on a global level to millions of I/O operations per second. We at Trademob have chosen Cassy as the backbone of our tracking platform and couldn't be happier. It's pretty serious stuff though and nothing for a quick prototype or the first few iterations of a product IMHO.

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Sorry but this is just nonsense.

Cassandra with PlayORM/Astyanax has been the easiest database for me to install, use and manage out of the 10+ I've tried. Far simpler to install/manage than MySQL Cluster or Riak, far easier to use than PostgreSQL and infinitely better to scale than MongoDB.

You don't have to understand ColumnFamilies, consistency or the different topology strategies. The defaults are fine and if you are a Java developer life couldn't possibly be simpler.

If you don't understand the implications of eventual consistency, you're heading for a fall.

It's not a trivial topic and unfortunately "it appears to work as you'd expect" on a small dev cluster which can lead to statements like yours.

Your parent's post is actually very very accurate.

I am not disputing that Cassandra has a learning curve but I just disagree that it is any different to every other database available today.

They ALL have issues and eventual consistency is a fundamental part of a distributed database so its something you have to learn either way.

Check out HyperDex, Hbase and BigTable for systems that provide better guarantees than "eventually."

You would need to define "consistency" in order to have a more reasonable discussion about what each system provides, but Cassandra certainly isn't only eventually consistent. You can choose the number of replicas that must respond in order to consider the read/write operation a success per operation, which allows you to have quorum-based strong consistency guarantees.

There are more details on the options here: http://www.datastax.com/docs/1.2/dml/data_consistency

Consistency is a safety property. HyperDex, Hbase and BigTable all provide linearizability, which has a well-defined meaning. Cassandra does not, and most of its descriptions of consistency only refer to the behavior of the system, and not the properties you can rely upon. Pointing to the number of replicas read or written only clouds the issue.

I think if you will write to Cassandra with consistency level ALL, you will get strong consistency. Or you can use write consistency = 1 and read = ALL, or write consistency = Quorum and read consistency = Quorum.

FoundationDB, RethinkDB

> You don't have to understand ColumnFamilies, consistency or the different topology strategies. The defaults are fine

Whaa?? Fine for what?

I agree with the OP. I used cassandra at a startup for a year, about a year ago, and haven't used it since last April. I'm sure things have progressed some (and we were using SuperColumns which a new user today might not) but the idea that it's a black box you don't need to understand? Not at the load we were putting it under.

Cassandra by itself is definitely complex.

But if you're a Java developer then PlayORM/Astyanax abstracts away almost all of the complexity and allow you to focus on your data model and not worry about the columns. Likewise for the preferences the defaults make sense and are pretty straightforward to change if you do need.

What is hard about using PostgreSQL?

>You don't have to understand ... consistency

This is a recipe for disaster. Cassandra requires careful understanding of its claimed consistency guarantees to be used properly. Proper use of the ConsistencyLevel argument is pretty critical if you want to build a real site that actually works under load.

I don't know how you can say it's "performant as hell" when it's actually slower than even MySQL for simple selects.

Selecting data is important, inserting is also important see: [1]A comparison of NoSQL dbs: Cassandra, HBase, MongoDB, Riak (includes MYSQL cluster)

[1] https://news.ycombinator.com/item?id=5076130

Yes, then you start thinking about the workload of the average webapp...

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