title: How do you deal with database IDs that get astronomically high
body: <p>This question doesn't relate to a problem that I've had (yet), but it keeps me up at night.  Theoretically, eventually, as the number of rows in a table goes up and up and up, the ID corresponding to each row will "run out" of numbers, won't it?  I guess that if you keep adding depth to the column value, you could keep it going up, but eventually there must be an upper limit, right?</p>
  
  <p>I've heard of a technique called "sharding" but haven't had it explained in enough detail to satisfy my curiosity.  Is the answer that you just keep adding more numbers, or is there a clever pattern to allow "repeat" IDs in their own sandbox.  What if these sandboxes have to interact?</p>