User blog comment:Wade Warren/How we deliver pages to you/@comment-3562424-20120229033015/@comment-3475413-20120314224819

Kanga, we install the new version of mediawiki on the same servers in a different directory and then when we're ready to make the switch we simply change a symlink to point to the new directory with the new version of the software. It's a rather simple process. The hardest and most time consuming pieces are the code/extension testing and finally the db/schema changes that usually accompany an upgrade. Each wiki has it's own database and with 300,000 of those it can take quite a long time to update.