Pathauto

Recently, a very mysterious problem has cost us quite a lot of time and some headache too. Before I explain, what happened, I want to mention, that it happened on a Drupal 7 Site on a MS SQL Server database. According to an issue on drupal.org, that I will mention later, it may also occur with PostegreSQL, but most likely not with MySQL. But I also have a general advice regarding pathauto patterns and best practices.