title: How to query two collections at the same time?
body: <p>I am using MongoDB and I ended up with two Collections (unintentionally).</p>
  
  <p>The first Collection (sample) has 100 million records (Tweets) with the following structure:</p>
  
  <pre><code>{
  "_id" : ObjectId("515af34297c2f607b822a54b"),
  "text" : "bla bla ",
  "id" : NumberLong("314965680476803072"),
  "user" : 
         {
          "screen_name" : "TheFroooggie",
          "time_zone" : "Amsterdam",
         },
  }
  </code></pre>
  
  <p>The second Collection (users) with 30 Million records of unique users from the tweet collection and it looks like this</p>
  
  <pre><code>{ "_id" : "000000_n", "target" : 1, "value" : { "count" : 5 } }
  </code></pre>
  
  <p>where the _id in the users collection is the user.screen_name from the tweets collection, the target is their status (spammer or not) and finally the value.count is the number a user appeared in our first  collection (sample) collection (e.g. number of captured tweets)</p>
  
  <p>Now I'd like to make the following query:</p>
  
  <p>I'd like to return all the documents from the sample collection (tweets) where the user has the target value = 1</p>
  
  <p>In other words, I want to return all the tweets of all the spammers for example. </p>