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   1  <!-- $Id: configuration.html,v 1.1.2.2 2009/08/11 19:19:15 weitzman Exp $ -->
   2  
   3  <p>Performing a large migration exercises a Drupal installation in different ways
   4  than normal production usage. There are several things you can do to improve the
   5  performance of your migration processes.</p>
   6  
   7  <h3>.htaccess</h3>
   8  
   9  <p>If you are going to upload large files through Table Wizard, you should increase
  10  the following parameters, as well as increasing Drupal's 
  11  <a href="&base_url&admin/settings/uploads">maximum file upload values</a>:</p>
  12  
  13  <pre>
  14    php_value max_input_time      600
  15    php_value upload_max_filesize 255M
  16    php_value post_max_size       255M
  17  </pre>
  18  
  19  <p>Bulk creation and deleting of nodes and users can strain memory usage - you
  20  should consider significantly boosting <em>memory_limit</em>:</p>
  21  
  22  <pre>
  23    php_value memory_limit       256M
  24  </pre>
  25  
  26  <p>When performing a migration process, whether interactively, via cron, or via drush, the
  27  Migrate module monitors execution time and exits a few seconds before 
  28  max_execution_time is exhausted, to avoid partial updates. To get the most out
  29  of each processing step (in light of <a href="http://drupal.org/node/375578">cron's 
  30  limitation to 240 seconds max</a>), set max_execution_time to 240 seconds:</p>
  31  
  32  <pre>
  33    php_value max_execution_time 240
  34  </pre>
  35  
  36  <h3>Drupal 6 Core patches</h3>
  37  
  38  <p>In normal Drupal usage, nodes and users are created and deleted one at a time -
  39  thus, the core is optimized for that kind of load and is not well optimized for
  40  the bulk operations that the Migrate module performs. The following patches are 
  41  recommended to help your performance when performing migrations.</p>
  42  
  43  <p>node_delete() unnecessarily caches the node being deleted - when hundreds or
  44  thousands of nodes are deleted in a single request, you can very quickly run out of memory.
  45  Go to <a href="http://drupal.org/node/287063">issue #287063</a> and apply the patch 
  46  in comment #8 to prevent this caching.</p> 
  47  
  48  <p>Deleting a user updates the comments and node_comment_statistics tables rows
  49  referencing that user's uid, but those columns are node indexed, making deletion
  50  of users in bulk very slow. The patch at 
  51  <a href="http://drupal.org/node/289504">http://drupal.org/node/289504</a> addresses
  52  this.</p>
  53  
  54  <p>Note: These patches have already been incorporated into Drupal 7.
  55  
  56  <h3>Other patches</h3>
  57  
  58  <p>When using the <a href="http://drupal.org/project/email_registration">Email 
  59  registration module</a>, if you would like an explicit username you're migrating
  60  to override that module's automated username generation, apply the patch at
  61  <a href="http://drupal.org/node/247717">http://drupal.org/node/247717</a>.</p>