title: What is the point of reverse indexing?
body: <p>I just learned about reverse indexing. The <a href="http://en.wikipedia.org/wiki/Reverse_index" rel="noreferrer">wikipedia</a> page says that </p>
  
  <blockquote>
    <p>In database management systems, a reverse key index strategy reverses
    the key value before entering it in the index.<a href="http://en.wikipedia.org/wiki/Reverse_index" rel="noreferrer">1</a> E.g., the value
    24538 becomes 83542 in the index. Reversing the key value is
    particularly useful for indexing data such as sequence numbers, where
    each new key value is greater than the prior value, i.e., values
    monotonically increase. Reverse key indexes have become particularly
    important in high volume transaction processing systems because they
    reduce contention for index blocks.</p>
  </blockquote>
  
  <p>Why is reversing the key value useful for indexing sequence numbers? Also, why do reverse indexes help reduce contention for index blocks in high volume systems? In short: what is the point of reverse indexing?</p>