Is the database-schema changed when I update from Mendix runtime 18.104.22.168. to 2.5.6? We consider updating to 2.5.6. Of course a backup of the database is made And the Mendix-model will also be backed-up (we create a tag in SVN), because I know you cannot open a 2.5.6. model in modeler 22.214.171.124' And we first deploy to T-env and then to P-env when approved But... In the case that QA has approved the 2.5.6 version for the production environment and on this environment it turns out to run very unstable... Is it then possible to switch back to 126.96.36.199.? Or is that doomed to failure? We think that this "rollback" can only be done if there are no changes in the database-schema, so can anyone inform? PS: I understand that rollingback should be avoided, but I'd like to know about the "what-if scenario"
As far as I recall, every version update (except minor bug fixes like from 2.5.4 to 188.8.131.52) has involved some database structure changes. There is no official way to roll back from a later version to an earlier one.
Whether this can be achieved in an emergency by hacking the database directly - you would need guidance from the Mendix guys to even attempt this. Better do your testing thoroughly in the T-env before pushing to P-env to avoid this issue
There will probably be some changes. And running a previous version of the framework on a later version of the database isn't officially supported. Personally I'd just record the changes it makes and try to reverse them in case you want to rollback for some reason.