title: Varchar or int for many records?
body: <p>For a site like Facebook, does it use <code>int</code> or <code>varchar</code>? For example, for the number of posts on Facebook, there are billions or trillions. So do you use <code>int</code> for each post id or do you use <code>varchar</code>? The max for int is  2,147,483,647 so I'm confused. Please help, thanks.</p>