title: Good NoSQL database for Write-Read Intensive Site
body: <p>Ok I do have a small messaging site for my client. Well its more likely a post-comment system(created in PHP). Now my client want a system that can comment to another existing comment and add some features like liking and tagging. Another thing is the existing system is heavily used by my client in his company as they use it like a skype chat(that makes it write-read intensive). well my client want's to use open source software as possible. so I used mysql community edition.</p>
  
  <p>Too much about my story... So I had a 1 week research about NoSql databases and I found it right for my requirements as my client wants to add features (that means adding and adding columns and tables from time to time.) Now these are nosql database systems that caught my eye.(well if you can suggest other nosql database system its ok)</p>
  
  <ol>
  <li>MongoDB</li>
  <li>CouchDB</li>
  <li>Redis</li>
  </ol>
  
  <p>Now my question is which of the three is good for my situation? I also read some bad things about those 3 nosql databases</p>
  
  <ol>
  <li>MongoDB is crappy on its 2.x version</li>
  <li>CouchDB is slow (my client doesn't want slow)</li>
  <li>Redis is memory-based so it just writes on the disk on certain intervals. so when the system crash in the middle of the interval then the data is lost</li>
  </ol>
  
  <p>I want to have some opinions about this and any advice that can help me to cope up with my upcoming situation</p>