"Clean up" drupal mysql database after Drupal 6 » 7 upgrade

I recently upgraded my website from Drupal 6 to Drupal 7. The number of tables in my MySQL database jumped from 135 tables to 283 tables. I may be wrong, but it seems to me that some of the tables are redundant copies left over from Drupal 6 (e.g., CCK fields now handled by Drupal 7 fields). Could/should I "clean up" t开发者_如何学编程he database by deleting the unused tables? How would I know which ones are safe to delete?

I believe that you should delete this tables if you know which ones are safe. ) Don't forget to make backup of your database.

I guess it is difficult to say which table belongs to which version of drupal. Make backup of your database and try to guess the tables to delete.