title: Hibernate IDENTITY vs SEQUENCE entity identifier generators
body: <p>This <a href="http://www.sql-server-performance.com/2011/sequence-sql-server-2011/" rel="noreferrer">article</a> says:</p>
  
  <blockquote>
    <p>Unlike identity, the next number for the column value will be retrieved from memory rather than <strong>from the disk</strong> – this makes Sequence significantly faster than Identity</p>
  </blockquote>
  
  <p>Does it mean that ID comes from disk in case of identity? If yes, then which disk and <strong>how</strong>?</p>
  
  <p>Using sequence, I can see in the log, an extra select query to DB while inserting a new record. But I didn't find that extra select query in the log in case of identity.
  Then <strong>how sequence becomes faster than identity</strong>?</p>