title: Cassandra or MongoDB for good scaling and big amount of queries
body: <p>I have the following situation. There are a lot of queries to database (commonly writing comments, reading profiles, etc...), and, I think will be more reads than writes. I want to have a good possibility to scaling db to a several servers. So, and I enjoy nosql:)
  As I understand by reading blogs and answers for question on StackOverflow (for example <a href="https://stackoverflow.com/questions/2892729/mongodb-vs-cassandra">this one</a>) the best choice in this situation is using Cassandra.</p>
  
  <p>So, the question is - is Cassandra more suitable for my purposes? Why?</p>
  
  <p>And the second question will be about async client libraries for <a href="https://github.com/facebook/tornado/wiki/Links" rel="nofollow noreferrer">Tornado</a> - do you know some implementations of this? As you can see on the wiki page linked above there are async clients only for mongodb and couchdb. And this fact also stops me. </p>
  
  <p>Maybe I can use MongoDB now (cause of async library esists and maybe in first time it will be faster than Cassandra on several servers but without async), and after some time convert data in mongo to cassandra. What do you think about it?</p>