title: IDs for Information on More Than One DB/Server
body: <p>I'm working on a project that I want to have be as flexible and scalable as possible from the beginning. A problem I'm concerned about is one best described by Joshua Schacter in <em>Founders at Work</em>, who noted it as one detail he wish he would've planned for ahead of time.</p>
  <blockquote>
  <p>Scaling past one machine, one database, is very challenging, even with replication. The tools that are there are not quite right.</p>
  <p>For example, when you add things to a table and it numbers them, that means you can't have a second machine also adding to them because the numbers will collide. So what do you do? You have to come up with some completely different way to do it.</p>
  <p>Do you have a central server that hands out number sets, or do you come up with something that's not numbers? Do you use random numbers and hope they never collide? Whatever it is, auto-assigned IDs just don't fly.</p>
  </blockquote>
  <p>Has anyone here faced this problem? What are ways to move beyond auto-incremented IDs, or is there a way to have them scale with multiple servers?</p>