Question

Each of the major DBMS products changes quite rapidly, and keeping DBMS software up-to-date can be a difficult task. As a DBA, what are the issues to consider when upgrading to a new DBMS version to have little or no disruption?

Answer 1

Answer:

Keeping each software up-to-date is a difficult task.

As a DBA you'll not have a lot to do. From DBA perspective it's enough to check changelog. If upgrade will not change/demage your data everything should be fine.

In general the problem is more complicated when other software use  those DB.

Explanation:

If DBMS is used by other software, the whole upgrade process have to be coordinated and synchronized with the software development team. They'll have to upgrade some library or some other parts of the software.