title: How Solr indexes & search works so fast?
body: <p>Does solr saves indexes in files or memory? I have reviewed document but it mentions both, how does it work so fast if it stores indexes in files? I mean I want to understand how it basically works? Where does it store indexes, and how searches are performed so fast? If its memory does it keep indexes loaded into memory all the time, or how does it work otherwise?</p>
  
  <p>I'm new to anything like this, and this is really a very basic questions which will help me to understand the technicalities involved in this.</p>
  
  <p>Thanks</p>