title: Should Lookup Table Foreign Keys Always be Indexed?
body: <p>If I have a lookup table with very few records in it (say, less than ten), should I bother putting an index on the Foreign Key of another table to which it is attached?  For that matter, does the lookup table even need an index on the Primary Key?  </p>
  
  <p>Specifically, is there any performance benefit that outweighs the overhead of maintaining the indexes?  If not, are there any benefits other than speed?</p>
  
  <p>Note: an example of a lookup table might be Order Status, where the tuples are:</p>
  
  <pre><code>1 - Order Received
  2 - In Process
  3 - Shipped
  4 - Paid
  </code></pre>