title: High extent scan fragmentation but low Logical Scan Fragmentation
body: <p>I'm still new to SQL Server, when I run DBCC SHOWCONTIG on table, it shows that Logical Scan Fragmentation is not big but Extent Scan Fragmentation is big, which made me a little confused.</p>
  
  <pre><code>    DBCC SHOWCONTIG scanning 'User' table...
      Table: 'User' (462624691); index ID: 1, database ID: 6
      TABLE level scan performed.
      - Pages Scanned................................: 2638
      - Extents Scanned..............................: 335
      - Extent Switches..............................: 578
      - Avg. Pages per Extent........................: 7.9
      - Scan Density [Best Count:Actual Count].......: 56.99% [330:579]
      - Logical Scan Fragmentation ..................: 12.93%
      - Extent Scan Fragmentation ...................: 94.03%
      - Avg. Bytes Free per Page.....................: 805.1
      - Avg. Page Density (full).....................: 90.05%
      DBCC execution completed. If DBCC printed error messages, contact your system administrator.
  </code></pre>
  
  <p>Seeing from the <a href="https://technet.microsoft.com/en-us/library/aa258803(v=sql.80).aspx" rel="nofollow">Manual on MSDN</a>, one is about fragmentation on pages and another is on extents. Is there other difference? How can Logical Scan Fragmentation is low while Extent Scan Fragmentation remains high?</p>
  
  <p>Also when we talk about "External fragmentation", it is more related with "Logical Scan Fragmentation" in the result or the "Extent Scan Fragmentation" in the result of SHOWCONTIG?</p>
  
  <p>Really appreciate any answer.</p>