title: Command line utility or C# code to compute 200,000 file changes in a directory hierarchy quickly?
body: <p>Using Microsoft <a href="http://support.microsoft.com/kb/841290" rel="nofollow noreferrer">FCIV</a> which computes SHA-1 file checksums, I created a text file with file names and checksums:</p>
  
  <pre><code>"8697c58c606122c30e2a20f1eabd6919" "g:\00258\99481\99481.eps"
  "b77a6b392c002bb9cc51f48170487dea" "g:\00258\99481\99481.eps"
  </code></pre>
  
  <p>My intent is to create a Jpeg thumbnail for any images that change.  However, this utility takes hours to generate a list.  I wanted to use SHA-1 because the Git folks find it useful (1 in 2^52 chance of collision, 5 commas).  MD5 produces several collisions with that sample size.  I want to use the SHA-1 as a unique identifier too.</p>
  
  <p>I need to quickly identify file changes and re-generate thumbnails only for changed files.  I would like to get these values in to SQL.  Any suggestions?  (For that matter, I need to read the image loading keywords in to SQL).  Time is difficult because twice a year, Microsoft's file creation and modification times change by an hour.</p>