title: Read mongodump output with go and mgo
body: <p>I'm trying to read a collection dump generated by mongodump. The file is a few gigabytes so I want to read it incrementally.</p>
  
  <p>I can read the first object with something like this:</p>
  
  <pre><code>buf := make([]byte, 100000)
  f, _ := os.Open(path)
  f.Read(buf)
  
  var m bson.M
  bson.Unmarshal(buf, &amp;m)
  </code></pre>
  
  <p>However I don't know how much of the buf was consumed, so I don't know how to read the next one.</p>
  
  <p>Is this possible with mgo?</p>