title: How to modify a large file remotely
body: <p>I have a large XML file, ~30 MB.</p>
  
  <p>Every now and then I need to update some of the values. I am using <code>element tree</code> module to modify the XML. I am currently fetching the entire file, updating it and then placing it again. SO there is ~60 MB of data transfer every time. Is there a way I update the file remotely?
  I am using the following code to update the file.</p>
  
  <pre><code>import xml.etree.ElementTree as ET
  
  tree = ET.parse("feed.xml")
  root = tree.getroot()
  
  skus = ["RUSSE20924","PSJAI22443"]
  qtys = [2,3]
  
  for child in root:
      sku = child.find("Product_Code").text.encode("utf-8")
      if sku in skus:
          print "found"
          i = skus.index(sku)
          child.find("Quantity").text = str(qtys[i])
          child.set('updated', 'yes')
  
  tree.write("feed.xml")
  </code></pre>