I'm not the original commenter, nor am I experienced with upgrading in general, but what I understand from the comment is that you always make sure that your current schema is compatible with the previous backend.
For example, this could mean that you don't delete any column that were still in use in the previous backend version.
This would have the advantage of letting you rollback your backend alone if anything wrong happens.
For example, this could mean that you don't delete any column that were still in use in the previous backend version.
This would have the advantage of letting you rollback your backend alone if anything wrong happens.