I need to run a script that might break `apt-get` database. What should I backup?

After some digging,i found out that apt-get database is managed by dpkg

From man dpkg

   /etc/dpkg/dpkg.cfg
          Configuration file with default options.

   /var/log/dpkg.log
          Default log file (see /etc/dpkg/dpkg.cfg(5) and option --log).

   The other files listed below are in their default directories, see option --admindir to see how to
   change locations of these files.

   /var/lib/dpkg/available
          List of available packages.

   /var/lib/dpkg/status
          Statuses  of  available packages. This file contains information about whether a package is
          marked for removing or not, whether it is installed or not, etc.  See  section  INFORMATION
          ABOUT PACKAGES for more info.

          The  status  file is backed up daily in /var/backups. It can be useful if it's lost or cor‐
          rupted due to filesystems troubles.

Also from The Debian FAQ,it says

It is important to understand that the higher level package management tools such as aptitude or synaptic rely on apt which, itself, relies on dpkg to manage the packages in the system.

So if dpkg puts its own database in /var/lib/dpkg/status, that means apt-get database and all other package mangers maintained by dpkg will also be in /var/lib/dpkg/status.So simply by backing up /var/lib/dpkg/status (of which dpkg already puts its backups in /var/backups/) will solve your worries of screwing up with apt-get.