In the newest WassUp WordPress plugin update (v.1.8.1), there is a precautionary notice about upgrading. This notice says that you should not upgrade if your site is busy. That is, you should check the number of current visitors online before upgrading and, if there are more than one regular visitors or multiple spiders online, don’t upgrade!!

WassUp is different from most plugins because once it is enabled it starts working and never stops until it is disabled, deactivated or your site goes down. Every visitor click, every spider hit, every search, and every feed request triggers WassUp to write data into it’s tables. The more popular your site is, the more data WassUp has to write in order to track visitors browsing your site.

An upgrade during a busy time for your site increases the odds that WassUp will be interrupted in the middle of a write operation. That kind of interruption can cause file corruption or can leave a permanent lock on WassUp tables. If that were to happen, WassUp would stop all new recordings until the lock is cleared or until ‘wp_wassup’ table is repaired. Note that this only affects WassUp, not WordPress itself, so your site would remain functioning.

If your site is always busy or you just can’t wait to upgrade, I recommend that you temporarily “disable recording” in WassUp >> Wassup-Options, [Statistics Recording] Tab, or put your site into “maintenance mode” prior to doing the upgrade. If you do this, always remember that you will have to manually re-enable recording or undo maintenance mode page when you have done upgrading.

For a seamless upgrade every time, always check the plugin’s “Installation” instructions at http://wordpress.org/extend/plugins/wassup/installation/ for any new installation/upgrade procedures that could affect your copy of WassUp.