title: Adding large number of unique values in MySql that may cross the range of sql integer
body: <p>I am building a simple social network and currently I am designing its database tables. I am  building a separate tables for comments. Each comment will have a unique comment id by which I will query them. The question is if we assume the situation that the site is becoming popular and a millions of users are posting tens of millions of comments, wouldn't at some point of time I will run out of range that the sql integer is providing? I don't have an idea how to do this or even if this situation is practical? If it is practical then how to handle this. I want my site to be scalable. </p>
  
  <p>And how long should be the range of integer lets say for 'Users' table (for storing users having unique 'userid'), the 'Posts' table  (for storing posts having unique 'postid') and comments table. I am using MySql and I will be building my website using Servlets. Any other suggestion is welcomed.</p>