Suppose an upgrade does not work and you want to recover from it. Using git (or another version control system) it is easy to revert the codebase to the state it was before the upgrade. But the database may not be so easy to restore.
Do Moodle upgrades chaage the database? If some do and some don't is there any way of telling which do before running them.
The context of this question is that I am migrating an old site which was not upgraded for years and I want the path to dfuture upgrades to be as clear as possible before they are done.
