title: When to use CouchDB vs RDBMS
body: <p>I am looking at CouchDB, which has a number of appealing features over relational databases including:</p>
  
  <ul>
  <li>intuitive REST/HTTP interface</li>
  <li>easy replication</li>
  <li>data stored as documents, rather than normalised tables</li>
  </ul>
  
  <p>I appreciate that this is not a mature product so should be adopted with caution, but am wondering whether it is actually a viable replacement for an RDBMS (in spite of the intro page saying otherwise - <a href="http://couchdb.apache.org/docs/intro.html" rel="noreferrer">http://couchdb.apache.org/docs/intro.html</a>). </p>
  
  <ol>
  <li>Under what circumstances would CouchDB be a better choice of database than an RDBMS (e.g. MySQL), e.g. in terms of scalability, design + development time, reliability and maintenance.</li>
  <li>Are there still cases where an RDBMS is still clearly the right choice?</li>
  <li>Is this an either-or choice, or is a hybrid solution more likely to emerge as best practice?</li>
  </ol>