title: v$sqlarea: why is elapsed_time less than user_io_time + cpu_time?
body: <p>When running:</p>
  
  <pre><code>select user_io_wait_time, cpu_time, elapsed_time, user_io_wait_time + cpu_time
  from v$sqlarea where /* filter */
  </code></pre>
  
  <p>I get the output as below. Can you please explain why the sum of cpu_time and user_io_wait_time is greater than the elapsed_time? I thought elapsed_time would be the total time spent on the query including user_io, cpu, system io, concurrency etc.. All returned rows represent long-running update statements. Oracle 10g. Thanks, Thomas.</p>
  
  <pre><code>USER_IO_WAIT    CPU_TIME    ELAPSED_TIME    USER_IO_WAIT+CPU_TIME
  721189651        32450000      742860743    753639651
  719109237        32540000      740826171    751649237
  720330754        32540000      741987150    752870754
  725473348        32670000      747215507    758143348
  720799316        32540000      742501530    753339316
  725361991        33000000      747416902    758361991
  725387023        32830000      747236752    758217023
  720383321        32210000      741849457    752593321
  </code></pre>