title: Clarifying the usefulness of Elastic Search
body: <p>I am a bit confused about the use of <code>ElasticSearch</code>. I have an application(<code>Ruby on Rails</code>) now with a relational Database (<code>Mysql</code>) and I am trying to benefit from the search functionalities <code>ElasticSearch</code> provides. I still want to use my relational database as before, but I want to use <code>ElasticSearch</code> only for searching. Therefore, can I use ES as a secondary storage? how will tell my application to always copy data from Mysql to ES? is there any best practices here?</p>
  
  <p>I have heard also that couchdb is good for searching, is it an alternative to ES or does it Provides different functionalities?  </p>