title: Stream a large file line by line from S3
body: <p>I have a few 10gb csv files in s3 that I'd like to use to seed my DB. I'm running a RoR application on Heroku and I can't figure out how to stream the csv line by line to process it as it's way too large to fit in memory and I can't use File.open to access an external file. </p>
  
  <p>I've looked into using Tempfile to stream bytes at a time, but they don't match up with new lines and reconstructing this in Ruby is difficult. </p>
  
  <p>Thank you!</p>