title: Google: Disable certain querystring in robots.txt
body: <pre><code>http://www.site.com/shop/maxi-dress?colourId=94&amp;optId=694
  http://www.site.com/shop/maxi-dress?colourId=94&amp;optId=694&amp;product_type=sale
  </code></pre>
  
  <p>I have thousands of URLs like the above. Different combinations and names.
  I also have duplicates of these URLs which have the query string <code>product_type=sale</code></p>
  
  <p>I want to disable Google from indexing anything with <code>product_type=sale</code></p>
  
  <p>Is this possible in robots.txt</p>