How is the multiuser aspect handled in Mendix?

i.e. How do I prevent that users opening the same object (record) overwrite each others changes in the database? When I open an object and while the object is in memory, another user accesses the same object, changes an attribute and commits. Now I change another attribute of the same object and try to commit, what will happen? Will the DB just also commit and I will overwrite the changes from the other user or Will the DB send an error that the object has been updated and I have to restart? If there is documentation about this topic just give me a hint where to find it. 
1 answers

There is indeed documentation about this. You can find it here:

But there is a module in the appstore you might find usefull if you need locking: Pessimistic locking

You can also build it yourself like for instance when you have a task that can be done by multiple people. You can then make a claim functionality  first so that the task is removed from all the other users tasklist.