title: Creating index takes very long time
body: <p>I created a collection in MongoDB consisting of <strong>11446615</strong> documents. </p>
  
  <p>Each document has the following form:</p>
  
  <pre><code>{ 
   "_id" : ObjectId("4e03dec7c3c365f574820835"), 
   "httpReferer" : "http://www.somewebsite.pl/art.php?id=13321&amp;b=1", 
   "words" : ["SEX", "DRUGS", "ROCKNROLL", "WHATEVER"],     
   "howMany" : 3 
  }
  </code></pre>
  
  <p><strong>httpReferer</strong>: just an url</p>
  
  <p><strong>words</strong>: words parsed from the url above. Size of the list is between 15 and 90.</p>
  
  <p>I am planning to use this database to obtain list of webpages which have similar content.</p>
  
  <p>I 'll by querying this collection using <strong>words</strong> field so I created (or rather started creating) index on this field:</p>
  
  <pre><code>db.my_coll.ensureIndex({words: 1})
  </code></pre>
  
  <p>I started creating index about 3 hours ago and it doesn't seem like it could finish in another 3 hours.</p>
  
  <p>How can I increase speed of indexing? Or maybe I should use completely another approach to this problem? Any ideas are welcome :)</p>