title: Database design - large fields
body: <p>Let's say, for example, that I have a list of articles in a blog. Each article has one image, each image has one thumbnail.</p>
  
  <p>When displaying a list of articles, each will be shown with the thumbnail; when showing a single article, it will be shown with the full-size image.</p>
  
  <p>This means I have three pieces of large (unknown size) data items with each article: image, thumbnail and text.</p>
  
  <p>What are the pros and cons of these designs:</p>
  
  <ol>
  <li>Articles table includes Thumbnail column and Image column</li>
  <li>Articles table includes Thumbnail column, Image stored in separate table</li>
  <li>Thumbnail and Image stored in a single separate table</li>
  <li>Thumbnail and Image stored in their own separate tables</li>
  <li>Site has write-access to a folder where Images and Thumbnails are stored, database contains URLs/filenames</li>
  </ol>
  
  <p>(any I haven't considered?)</p>
  
  <p>If it makes a difference, and I don't think it should, the site will be written in Ruby/Rails, using Postgres or MySql.</p>