Would it be wise not to shutdown a db for an OS update?

Every package that has an update available will get updated less kernel and ldap for compatibility reasons. The plan is not to re-start the db. How safe is this? What could be scenarios that arise from this?

My feeling is that we should not do it this way. Here is way: 

The db will not use the updated utilities so if we are patching for security reasons then it somehow defeats the purpose of the OS upgrade- as far as I understand

By not shutting down the databases  we cannot test if there are conflicts between the OS patches and the db software so next time the db comes down we won't know if it is the work we just did on the database or the previous one from the OS. This approach adds uncertainty to our work- is it necessary?