eBharatBase.com has more than 2, 60,000 nodes. We changed the pattern of url aliases to be generated for each node. We tried to generate from admin interface of pathauto module, the system hangs everytime.
The reason - query to fetch node was taking much longer to execute, and php/drupal used to show error message since they were not receiving any response.
To tackle this problem, i started writing small but effect piece of code to generate the url alises of all 2,60,000+ nodes.
1) Created script named "generate_url_alias.php" in drupal root folder